Programs & Examples On #Cookbook

tslint / codelyzer / ng lint error: "for (... in ...) statements must be filtered with an if statement"

use Object.keys:

Object.keys(this.formErrors).map(key => {
  this.formErrors[key] = '';
  const control = form.get(key);

  if(control && control.dirty && !control.valid) {
    const messages = this.validationMessages[key];
    Object.keys(control.errors).map(key2 => {
      this.formErrors[key] += messages[key2] + ' ';
    });
  }
});

Angular 2: Can't bind to 'ngModel' since it isn't a known property of 'input'

import {FormControl,FormGroup} from '@angular/forms';

import {FormsModule,ReactiveFormsModule} from '@angular/forms';

You should also add the missing ones.

Change bar plot colour in geom_bar with ggplot2 in r

If you want all the bars to get the same color (fill), you can easily add it inside geom_bar.

ggplot(data=df, aes(x=c1+c2/2, y=c3)) + 
geom_bar(stat="identity", width=c2, fill = "#FF6666")

enter image description here

Add fill = the_name_of_your_var inside aes to change the colors depending of the variable :

c4 = c("A", "B", "C")
df = cbind(df, c4)
ggplot(data=df, aes(x=c1+c2/2, y=c3, fill = c4)) + 
geom_bar(stat="identity", width=c2)

enter image description here

Use scale_fill_manual() if you want to manually the change of colors.

ggplot(data=df, aes(x=c1+c2/2, y=c3, fill = c4)) + 
geom_bar(stat="identity", width=c2) + 
scale_fill_manual("legend", values = c("A" = "black", "B" = "orange", "C" = "blue"))

enter image description here

Change the location of the ~ directory in a Windows install of Git Bash

So, $HOME is what I need to modify.

However I have been unable to find where this mythical $HOME variable is set so I assumed it was a Linux system version of PATH or something.

Git 2.23 (Q3 2019) is quite explicit on how HOME is set.

See commit e12a955 (04 Jul 2019) by Karsten Blees (kblees).
(Merged by Junio C Hamano -- gitster -- in commit fc613d2, 19 Jul 2019)

mingw: initialize HOME on startup

HOME initialization was historically duplicated in many different places, including /etc/profile, launch scripts such as git-bash.vbs and gitk.cmd, and (although slightly broken) in the git-wrapper.

Even unrelated projects such as GitExtensions and TortoiseGit need to implement the same logic to be able to call git directly.

Initialize HOME in Git's own startup code so that we can eventually retire all the duplicate initialization code.

Now, mingw.c includes the following code:

/* calculate HOME if not set */
if (!getenv("HOME")) {
    /*
     * try $HOMEDRIVE$HOMEPATH - the home share may be a network
     * location, thus also check if the path exists (i.e. is not
     * disconnected)
     */
    if ((tmp = getenv("HOMEDRIVE"))) {
        struct strbuf buf = STRBUF_INIT;
        strbuf_addstr(&buf, tmp);
        if ((tmp = getenv("HOMEPATH"))) {
            strbuf_addstr(&buf, tmp);
            if (is_directory(buf.buf))
                setenv("HOME", buf.buf, 1);
            else
                tmp = NULL; /* use $USERPROFILE */
        }
        strbuf_release(&buf);
    }
    /* use $USERPROFILE if the home share is not available */
    if (!tmp && (tmp = getenv("USERPROFILE")))
        setenv("HOME", tmp, 1);
}

In R, dealing with Error: ggplot2 doesn't know how to deal with data of class numeric

The error happens because of you are trying to map a numeric vector to data in geom_errorbar: GVW[1:64,3]. ggplot only works with data.frame.

In general, you shouldn't subset inside ggplot calls. You are doing so because your standard errors are stored in four separate objects. Add them to your original data.frame and you will be able to plot everything in one call.

Here with a dplyr solution to summarise the data and compute the standard error beforehand.

library(dplyr)
d <- GVW %>% group_by(Genotype,variable) %>%
    summarise(mean = mean(value),se = sd(value) / sqrt(n()))

ggplot(d, aes(x = variable, y = mean, fill = Genotype)) + 
  geom_bar(position = position_dodge(), stat = "identity", 
      colour="black", size=.3) +
  geom_errorbar(aes(ymin = mean - se, ymax = mean + se), 
      size=.3, width=.2, position=position_dodge(.9)) +
  xlab("Time") +
  ylab("Weight [g]") +
  scale_fill_hue(name = "Genotype", breaks = c("KO", "WT"), 
      labels = c("Knock-out", "Wild type")) +
  ggtitle("Effect of genotype on weight-gain") +
  scale_y_continuous(breaks = 0:20*4) +
  theme_bw()

Creating lowpass filter in SciPy - understanding methods and units

A few comments:

  • The Nyquist frequency is half the sampling rate.
  • You are working with regularly sampled data, so you want a digital filter, not an analog filter. This means you should not use analog=True in the call to butter, and you should use scipy.signal.freqz (not freqs) to generate the frequency response.
  • One goal of those short utility functions is to allow you to leave all your frequencies expressed in Hz. You shouldn't have to convert to rad/sec. As long as you express your frequencies with consistent units, the scaling in the utility functions takes care of the normalization for you.

Here's my modified version of your script, followed by the plot that it generates.

import numpy as np
from scipy.signal import butter, lfilter, freqz
import matplotlib.pyplot as plt


def butter_lowpass(cutoff, fs, order=5):
    nyq = 0.5 * fs
    normal_cutoff = cutoff / nyq
    b, a = butter(order, normal_cutoff, btype='low', analog=False)
    return b, a

def butter_lowpass_filter(data, cutoff, fs, order=5):
    b, a = butter_lowpass(cutoff, fs, order=order)
    y = lfilter(b, a, data)
    return y


# Filter requirements.
order = 6
fs = 30.0       # sample rate, Hz
cutoff = 3.667  # desired cutoff frequency of the filter, Hz

# Get the filter coefficients so we can check its frequency response.
b, a = butter_lowpass(cutoff, fs, order)

# Plot the frequency response.
w, h = freqz(b, a, worN=8000)
plt.subplot(2, 1, 1)
plt.plot(0.5*fs*w/np.pi, np.abs(h), 'b')
plt.plot(cutoff, 0.5*np.sqrt(2), 'ko')
plt.axvline(cutoff, color='k')
plt.xlim(0, 0.5*fs)
plt.title("Lowpass Filter Frequency Response")
plt.xlabel('Frequency [Hz]')
plt.grid()


# Demonstrate the use of the filter.
# First make some data to be filtered.
T = 5.0         # seconds
n = int(T * fs) # total number of samples
t = np.linspace(0, T, n, endpoint=False)
# "Noisy" data.  We want to recover the 1.2 Hz signal from this.
data = np.sin(1.2*2*np.pi*t) + 1.5*np.cos(9*2*np.pi*t) + 0.5*np.sin(12.0*2*np.pi*t)

# Filter the data, and plot both the original and filtered signals.
y = butter_lowpass_filter(data, cutoff, fs, order)

plt.subplot(2, 1, 2)
plt.plot(t, data, 'b-', label='data')
plt.plot(t, y, 'g-', linewidth=2, label='filtered data')
plt.xlabel('Time [sec]')
plt.grid()
plt.legend()

plt.subplots_adjust(hspace=0.35)
plt.show()

lowpass example

Write objects into file with Node.js

obj is an array in your example.

fs.writeFileSync(filename, data, [options]) requires either String or Buffer in the data parameter. see docs.

Try to write the array in a string format:

// writes 'https://twitter.com/#!/101Cookbooks', 'http://www.facebook.com/101cookbooks'
fs.writeFileSync('./data.json', obj.join(',') , 'utf-8'); 

Or:

// writes ['https://twitter.com/#!/101Cookbooks', 'http://www.facebook.com/101cookbooks']
var util = require('util');
fs.writeFileSync('./data.json', util.inspect(obj) , 'utf-8');

edit: The reason you see the array in your example is because node's implementation of console.log doesn't just call toString, it calls util.format see console.js source

Symfony - generate url with parameter in controller

make sure your controller extends Symfony\Bundle\FrameworkBundle\Controller\Controller;

you should also check app/console debug:router in terminal to see what name symfony has named the route

in my case it used a minus instead of an underscore

i.e blog-show

$uri = $this->generateUrl('blog-show', ['slug' => 'my-blog-post']);

YAML: Do I need quotes for strings in YAML?

After a brief review of the YAML cookbook cited in the question and some testing, here's my interpretation:

  • In general, you don't need quotes.
  • Use quotes to force a string, e.g. if your key or value is 10 but you want it to return a String and not a Fixnum, write '10' or "10".
  • Use quotes if your value includes special characters, (e.g. :, {, }, [, ], ,, &, *, #, ?, |, -, <, >, =, !, %, @, \).
  • Single quotes let you put almost any character in your string, and won't try to parse escape codes. '\n' would be returned as the string \n.
  • Double quotes parse escape codes. "\n" would be returned as a line feed character.
  • The exclamation mark introduces a method, e.g. !ruby/sym to return a Ruby symbol.

Seems to me that the best approach would be to not use quotes unless you have to, and then to use single quotes unless you specifically want to process escape codes.

Update

"Yes" and "No" should be enclosed in quotes (single or double) or else they will be interpreted as TrueClass and FalseClass values:

en:
  yesno:
    'yes': 'Yes'
    'no': 'No'

Create an ISO date object in javascript

In node, the Mongo driver will give you an ISO string, not the object. (ex: Mon Nov 24 2014 01:30:34 GMT-0800 (PST)) So, simply convert it to a js Date by: new Date(ISOString);

Arrays vs Vectors: Introductory Similarities and Differences

arrays:

  • are a builtin language construct;
  • come almost unmodified from C89;
  • provide just a contiguous, indexable sequence of elements; no bells and whistles;
  • are of fixed size; you can't resize an array in C++ (unless it's an array of POD and it's allocated with malloc);
  • their size must be a compile-time constant unless they are allocated dynamically;
  • they take their storage space depending from the scope where you declare them;
  • if dynamically allocated, you must explicitly deallocate them;
  • if they are dynamically allocated, you just get a pointer, and you can't determine their size; otherwise, you can use sizeof (hence the common idiom sizeof(arr)/sizeof(*arr), that however fails silently when used inadvertently on a pointer);
  • automatically decay to a pointers in most situations; in particular, this happens when passing them to a function, which usually requires passing a separate parameter for their size;
  • can't be returned from a function;
  • can't be copied/assigned directly;
  • dynamical arrays of objects require a default constructor, since all their elements must be constructed first;

std::vector:

  • is a template class;
  • is a C++ only construct;
  • is implemented as a dynamic array;
  • grows and shrinks dynamically;
  • automatically manage their memory, which is freed on destruction;
  • can be passed to/returned from functions (by value);
  • can be copied/assigned (this performs a deep copy of all the stored elements);
  • doesn't decay to pointers, but you can explicitly get a pointer to their data (&vec[0] is guaranteed to work as expected);
  • always brings along with the internal dynamic array its size (how many elements are currently stored) and capacity (how many elements can be stored in the currently allocated block);
  • the internal dynamic array is not allocated inside the object itself (which just contains a few "bookkeeping" fields), but is allocated dynamically by the allocator specified in the relevant template parameter; the default one gets the memory from the freestore (the so-called heap), independently from how where the actual object is allocated;
  • for this reason, they may be less efficient than "regular" arrays for small, short-lived, local arrays;
  • when reallocating, the objects are copied (moved, in C++11);
  • does not require a default constructor for the objects being stored;
  • is better integrated with the rest of the so-called STL (it provides the begin()/end() methods, the usual STL typedefs, ...)

Also consider the "modern alternative" to arrays - std::array; I already described in another answer the difference between std::vector and std::array, you may want to have a look at it.

Matplotlib discrete colorbar

The above answers are good, except they don't have proper tick placement on the colorbar. I like having the ticks in the middle of the color so that the number -> color mapping is more clear. You can solve this problem by changing the limits of the matshow call:

import matplotlib.pyplot as plt
import numpy as np

def discrete_matshow(data):
    #get discrete colormap
    cmap = plt.get_cmap('RdBu', np.max(data)-np.min(data)+1)
    # set limits .5 outside true range
    mat = plt.matshow(data,cmap=cmap,vmin = np.min(data)-.5, vmax = np.max(data)+.5)
    #tell the colorbar to tick at integers
    cax = plt.colorbar(mat, ticks=np.arange(np.min(data),np.max(data)+1))

#generate data
a=np.random.randint(1, 9, size=(10, 10))
discrete_matshow(a)

example of discrete colorbar

Heatmap in matplotlib with pcolor?

Main issue is that you first need to set the location of your x and y ticks. Also, it helps to use the more object-oriented interface to matplotlib. Namely, interact with the axes object directly.

import matplotlib.pyplot as plt
import numpy as np
column_labels = list('ABCD')
row_labels = list('WXYZ')
data = np.random.rand(4,4)
fig, ax = plt.subplots()
heatmap = ax.pcolor(data)

# put the major ticks at the middle of each cell, notice "reverse" use of dimension
ax.set_yticks(np.arange(data.shape[0])+0.5, minor=False)
ax.set_xticks(np.arange(data.shape[1])+0.5, minor=False)


ax.set_xticklabels(row_labels, minor=False)
ax.set_yticklabels(column_labels, minor=False)
plt.show()

Hope that helps.

How to implement band-pass Butterworth filter with Scipy.signal.butter

For a bandpass filter, ws is a tuple containing the lower and upper corner frequencies. These represent the digital frequency where the filter response is 3 dB less than the passband.

wp is a tuple containing the stop band digital frequencies. They represent the location where the maximum attenuation begins.

gpass is the maximum attenutation in the passband in dB while gstop is the attentuation in the stopbands.

Say, for example, you wanted to design a filter for a sampling rate of 8000 samples/sec having corner frequencies of 300 and 3100 Hz. The Nyquist frequency is the sample rate divided by two, or in this example, 4000 Hz. The equivalent digital frequency is 1.0. The two corner frequencies are then 300/4000 and 3100/4000.

Now lets say you wanted the stopbands to be down 30 dB +/- 100 Hz from the corner frequencies. Thus, your stopbands would start at 200 and 3200 Hz resulting in the digital frequencies of 200/4000 and 3200/4000.

To create your filter, you'd call buttord as

fs = 8000.0
fso2 = fs/2
N,wn = scipy.signal.buttord(ws=[300/fso2,3100/fso2], wp=[200/fs02,3200/fs02],
   gpass=0.0, gstop=30.0)

The length of the resulting filter will be dependent upon the depth of the stop bands and the steepness of the response curve which is determined by the difference between the corner frequency and stopband frequency.

MongoDB/Mongoose querying at a specific date?

We had an issue relating to duplicated data in our database, with a date field having multiple values where we were meant to have 1. I thought I'd add the way we resolved the issue for reference.

We have a collection called "data" with a numeric "value" field and a date "date" field. We had a process which we thought was idempotent, but ended up adding 2 x values per day on second run:

{ "_id" : "1", "type":"x", "value":1.23, date : ISODate("2013-05-21T08:00:00Z")}
{ "_id" : "2", "type":"x", "value":1.23, date : ISODate("2013-05-21T17:00:00Z")}

We only need 1 of the 2 records, so had to resort the javascript to clean up the db. Our initial approach was going to be to iterate through the results and remove any field with a time of between 6am and 11am (all duplicates were in the morning), but during implementation, made a change. Here's the script used to fix it:

var data = db.data.find({"type" : "x"})
var found = [];
while (data.hasNext()){
    var datum = data.next();
    var rdate = datum.date;
    // instead of the next set of conditions, we could have just used rdate.getHour() and checked if it was in the morning, but this approach was slightly better...
    if (typeof found[rdate.getDate()+"-"+rdate.getMonth() + "-" + rdate.getFullYear()] !== "undefined") {
       if (datum.value != found[rdate.getDate()+"-"+rdate.getMonth() + "-" + rdate.getFullYear()]) {
           print("DISCREPENCY!!!: " + datum._id + " for date " + datum.date);
       }
       else {
           print("Removing " + datum._id);
           db.data.remove({ "_id": datum._id});
       }
    }
    else {
       found[rdate.getDate()+"-"+rdate.getMonth() + "-" + rdate.getFullYear()] = datum.value;
    }
}

and then ran it with mongo thedatabase fixer_script.js

How to get the server path to the web directory in Symfony2 from inside the controller?

$host = $request->server->get('HTTP_HOST');
$base = (!empty($request->server->get('BASE'))) ? $request->server->get('BASE') : '';
$getBaseUrl = $host.$base;

why is plotting with Matplotlib so slow?

To start, Joe Kington's answer provides very good advice using a gui-neutral approach, and you should definitely take his advice (especially about Blitting) and put it into practice. More info on this approach, read the Matplotlib Cookbook

However, the non-GUI-neutral (GUI-biased?) approach is key to speeding up the plotting. In other words, the backend is extremely important to plot speed.

Put these two lines before you import anything else from matplotlib:

import matplotlib
matplotlib.use('GTKAgg') 

Of course, there are various options to use instead of GTKAgg, but according to the cookbook mentioned before, this was the fastest. See the link about backends for more options.

Using Gradle to build a jar with dependencies

I use task shadowJar by plugin . com.github.jengelman.gradle.plugins:shadow:5.2.0

Usage just run ./gradlew app::shadowJar result file will be at MyProject/app/build/libs/shadow.jar

top level build.gradle file :

 apply plugin: 'kotlin'

buildscript {
    ext.kotlin_version = '1.3.61'

    repositories {
        mavenLocal()
        mavenCentral()
        jcenter()
    }

    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.github.jengelman.gradle.plugins:shadow:5.2.0'
    }
}

app module level build.gradle file

apply plugin: 'java'
apply plugin: 'kotlin'
apply plugin: 'kotlin-kapt'
apply plugin: 'application'
apply plugin: 'com.github.johnrengelman.shadow'

sourceCompatibility = 1.8

kapt {
    generateStubs = true
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])

    implementation "org.seleniumhq.selenium:selenium-java:4.0.0-alpha-4"
    shadow "org.seleniumhq.selenium:selenium-java:4.0.0-alpha-4"

    implementation project(":module_remote")
    shadow project(":module_remote")
}

jar {
    exclude 'META-INF/*.SF', 'META-INF/*.DSA', 'META-INF/*.RSA', 'META-INF/*.MF'
    manifest {
        attributes(
                'Main-Class': 'com.github.kolyall.TheApplication',
                'Class-Path': configurations.compile.files.collect { "lib/$it.name" }.join(' ')
        )
    }
}

shadowJar {
    baseName = 'shadow'
    classifier = ''
    archiveVersion = ''
    mainClassName = 'com.github.kolyall.TheApplication'

    mergeServiceFiles()
}

How to resize an image with OpenCV2.0 and Python2.6

If you wish to use CV2, you need to use the resize function.

For example, this will resize both axes by half:

small = cv2.resize(image, (0,0), fx=0.5, fy=0.5) 

and this will resize the image to have 100 cols (width) and 50 rows (height):

resized_image = cv2.resize(image, (100, 50)) 

Another option is to use scipy module, by using:

small = scipy.misc.imresize(image, 0.5)

There are obviously more options you can read in the documentation of those functions (cv2.resize, scipy.misc.imresize).


Update:
According to the SciPy documentation:

imresize is deprecated in SciPy 1.0.0, and will be removed in 1.2.0.
Use skimage.transform.resize instead.

Note that if you're looking to resize by a factor, you may actually want skimage.transform.rescale.

Understanding generators in Python

First of all, the term generator originally was somewhat ill-defined in Python, leading to lots of confusion. You probably mean iterators and iterables (see here). Then in Python there are also generator functions (which return a generator object), generator objects (which are iterators) and generator expressions (which are evaluated to a generator object).

According to the glossary entry for generator it seems that the official terminology is now that generator is short for "generator function". In the past the documentation defined the terms inconsistently, but fortunately this has been fixed.

It might still be a good idea to be precise and avoid the term "generator" without further specification.

What does asterisk * mean in Python?

See Function Definitions in the Language Reference.

If the form *identifier is present, it is initialized to a tuple receiving any excess positional parameters, defaulting to the empty tuple. If the form **identifier is present, it is initialized to a new dictionary receiving any excess keyword arguments, defaulting to a new empty dictionary.

Also, see Function Calls.

Assuming that one knows what positional and keyword arguments are, here are some examples:

Example 1:

# Excess keyword argument (python 2) example:
def foo(a, b, c, **args):
    print "a = %s" % (a,)
    print "b = %s" % (b,)
    print "c = %s" % (c,)
    print args

foo(a="testa", d="excess", c="testc", b="testb", k="another_excess")

As you can see in the above example, we only have parameters a, b, c in the signature of the foo function. Since d and k are not present, they are put into the args dictionary. The output of the program is:

a = testa
b = testb
c = testc
{'k': 'another_excess', 'd': 'excess'}

Example 2:

# Excess positional argument (python 2) example:
def foo(a, b, c, *args):
    print "a = %s" % (a,)
    print "b = %s" % (b,)
    print "c = %s" % (c,)
    print args

foo("testa", "testb", "testc", "excess", "another_excess")

Here, since we're testing positional arguments, the excess ones have to be on the end, and *args packs them into a tuple, so the output of this program is:

a = testa
b = testb
c = testc
('excess', 'another_excess')

You can also unpack a dictionary or a tuple into arguments of a function:

def foo(a,b,c,**args):
    print "a=%s" % (a,)
    print "b=%s" % (b,)
    print "c=%s" % (c,)
    print "args=%s" % (args,)

argdict = dict(a="testa", b="testb", c="testc", excessarg="string")
foo(**argdict)

Prints:

a=testa
b=testb
c=testc
args={'excessarg': 'string'}

And

def foo(a,b,c,*args):
    print "a=%s" % (a,)
    print "b=%s" % (b,)
    print "c=%s" % (c,)
    print "args=%s" % (args,)

argtuple = ("testa","testb","testc","excess")
foo(*argtuple)

Prints:

a=testa
b=testb
c=testc
args=('excess',)

Remove HTML Tags from an NSString on the iPhone

If you are willing to use Three20 framework, it has a category on NSString that adds stringByRemovingHTMLTags method. See NSStringAdditions.h in Three20Core subproject.

Language Books/Tutorials for popular languages

One site I keep coming back to is http://www.javapractices.com. It covers most of the techniques that are discussed in the Effective Java book. Also another good site to check up coding examples (from basic to advanced) is http://www.java2s.com

how to use the Box-Cox power transformation in R

If I want tranfer only the response variable y instead of a linear model with x specified, eg I wanna transfer/normalize a list of data, I can take 1 for x, then the object becomes a linear model:

library(MASS)
y = rf(500,30,30)
hist(y,breaks = 12)
result = boxcox(y~1, lambda = seq(-5,5,0.5))
mylambda = result$x[which.max(result$y)]
mylambda
y2 = (y^mylambda-1)/mylambda
hist(y2)

SQL use CASE statement in WHERE IN clause

I realize this has been answered, but there is a slight issue with the accepted solution. It will return false positives. Easy to fix:

SELECT * FROM Products P    
WHERE (@Status='published' and P.Status IN (1,3))
   or (@Status='standby' and P.Status IN  (2,5,9,6))
   or (@Status='deleted' and P.Status IN (4,5,8,10))
   or (@Status not in ('published','standby','deleted') and P.Status IN (1,2))

Parentheses aren't needed (although perhaps easier to read hence why I included them).

How can I prevent the textarea from stretching beyond his parent DIV element? (google-chrome issue only)

textarea {
width: 700px;  
height: 100px;
resize: none; }

assign your required width and height for the textarea and then use. resize: none ; css property which will disable the textarea's stretchable property.

How to generate random float number in C

Try:

float x = (float)rand()/(float)(RAND_MAX/a);

To understand how this works consider the following.

N = a random value in [0..RAND_MAX] inclusively.

The above equation (removing the casts for clarity) becomes:

N/(RAND_MAX/a)

But division by a fraction is the equivalent to multiplying by said fraction's reciprocal, so this is equivalent to:

N * (a/RAND_MAX)

which can be rewritten as:

a * (N/RAND_MAX)

Considering N/RAND_MAX is always a floating point value between 0.0 and 1.0, this will generate a value between 0.0 and a.

Alternatively, you can use the following, which effectively does the breakdown I showed above. I actually prefer this simply because it is clearer what is actually going on (to me, anyway):

float x = ((float)rand()/(float)(RAND_MAX)) * a;

Note: the floating point representation of a must be exact or this will never hit your absolute edge case of a (it will get close). See this article for the gritty details about why.

Sample

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(int argc, char *argv[])
{
    srand((unsigned int)time(NULL));

    float a = 5.0;
    for (int i=0;i<20;i++)
        printf("%f\n", ((float)rand()/(float)(RAND_MAX)) * a);
    return 0;
}

Output

1.625741
3.832026
4.853078
0.687247
0.568085
2.810053
3.561830
3.674827
2.814782
3.047727
3.154944
0.141873
4.464814
0.124696
0.766487
2.349450
2.201889
2.148071
2.624953
2.578719

How to remove all elements in String array in java?

If example is not final then a simple reassignment would work:

example = new String[example.length];

This assumes you need the array to remain the same size. If that's not necessary then create an empty array:

example = new String[0];

If it is final then you could null out all the elements:

Arrays.fill( example, null );

How to kill a running SELECT statement

This is what I use. I do this first query to find the sessions and the users:

select s.sid, s.serial#, p.spid, s.username, s.schemaname
     , s.program, s.terminal, s.osuser
  from v$session s
  join v$process p
    on s.paddr = p.addr
 where s.type != 'BACKGROUND';

This will let me know if there are multiple sessions for the same user. Then I usually check to verify if a session is blocking the database.

SELECT SID, SQL_ID, USERNAME, BLOCKING_SESSION, COMMAND, MODULE, STATUS FROM v$session WHERE BLOCKING_SESSION IS NOT NULL;  

Then I run an ALTER statement to kill a specific session in this format:

ALTER SYSTEM KILL SESSION 'sid,serial#'; 

For example:

ALTER SYSTEM KILL SESSION '314, 2643';

How to create a shared library with cmake?

This minimal CMakeLists.txt file compiles a simple shared library:

cmake_minimum_required(VERSION 2.8)

project (test)
set(CMAKE_BUILD_TYPE Release)

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
add_library(test SHARED src/test.cpp)

However, I have no experience copying files to a different destination with CMake. The file command with the COPY/INSTALL signature looks like it might be useful.

Wait for a process to finish

I found "kill -0" does not work if the process is owned by root (or other), so I used pgrep and came up with:

while pgrep -u root process_name > /dev/null; do sleep 1; done

This would have the disadvantage of probably matching zombie processes.

How to use absolute path in twig functions

I've used the following advice from the docs https://symfony.com/doc/current/console/request_context.html to get absolute urls in emails:

# config/services.yaml
parameters:
    router.request_context.host: 'example.org'
    router.request_context.scheme: 'https'

multiple classes on single element html

It's a good practice if you need them. It's also a good practice is they make sense, so future coders can understand what you're doing.

But generally, no it's not a good practice to attach 10 class names to an object because most likely whatever you're using them for, you could accomplish the same thing with far fewer classes. Probably just 1 or 2.

To qualify that statement, javascript plugins and scripts may append far more classnames to do whatever it is they're going to do. Modernizr for example appends anywhere from 5 - 25 classes to your body tag, and there's a very good reason for it. jQuery UI appends lots of classnames when you use one of the widgets in that library.

What is the reason for java.lang.IllegalArgumentException: No enum const class even though iterating through values() works just fine?

That's because you defined your own version of name for your enum, and getByName doesn't use that.

getByName("COLUMN_HEADINGS") would probably work.

XSS prevention in JSP/Servlet web application

If you want to make sure that your $ operator does not suffer from XSS hack you can implement ServletContextListener and do some checks there.

The complete solution at: http://pukkaone.github.io/2011/01/03/jsp-cross-site-scripting-elresolver.html

@WebListener
public class EscapeXmlELResolverListener implements ServletContextListener {
    private static final Logger LOG = LoggerFactory.getLogger(EscapeXmlELResolverListener.class);


    @Override
    public void contextInitialized(ServletContextEvent event) {
        LOG.info("EscapeXmlELResolverListener initialized ...");        
        JspFactory.getDefaultFactory()
                .getJspApplicationContext(event.getServletContext())
                .addELResolver(new EscapeXmlELResolver());

    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        LOG.info("EscapeXmlELResolverListener destroyed");
    }


    /**
     * {@link ELResolver} which escapes XML in String values.
     */
    public class EscapeXmlELResolver extends ELResolver {

        private ThreadLocal<Boolean> excludeMe = new ThreadLocal<Boolean>() {
            @Override
            protected Boolean initialValue() {
                return Boolean.FALSE;
            }
        };

        @Override
        public Object getValue(ELContext context, Object base, Object property) {

            try {
                    if (excludeMe.get()) {
                        return null;
                    }

                    // This resolver is in the original resolver chain. To prevent
                    // infinite recursion, set a flag to prevent this resolver from
                    // invoking the original resolver chain again when its turn in the
                    // chain comes around.
                    excludeMe.set(Boolean.TRUE);
                    Object value = context.getELResolver().getValue(
                            context, base, property);

                    if (value instanceof String) {
                        value = StringEscapeUtils.escapeHtml4((String) value);
                    }
                    return value;
            } finally {
                excludeMe.remove();
            }
        }

        @Override
        public Class<?> getCommonPropertyType(ELContext context, Object base) {
            return null;
        }

        @Override
        public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base){
            return null;
        }

        @Override
        public Class<?> getType(ELContext context, Object base, Object property) {
            return null;
        }

        @Override
        public boolean isReadOnly(ELContext context, Object base, Object property) {
            return true;
        }

        @Override
        public void setValue(ELContext context, Object base, Object property, Object value){
            throw new UnsupportedOperationException();
        }

    }

}

Again: This only guards the $. Please also see other answers.

How to create a new figure in MATLAB?

As has already been said: figure will create a new figure for your next plots. While calling figure you can also configure it. Example:

figHandle = figure('Name', 'Name of Figure', 'OuterPosition',[1, 1, scrsz(3), scrsz(4)]);

The example sets the name for the window and the outer size of it in relation to the used screen. Here figHandle is the handle to the resulting figure and can be used later to change appearance and content. Examples:

Dot notation:

figHandle.PaperOrientation = 'portrait';
figHandle.PaperUnits = 'centimeters';

Old Style:

set(figHandle, 'PaperOrientation', 'portrait', 'PaperUnits', 'centimeters');

Using the handle with dot notation or set, options for printing are configured here.

By keeping the handles for the figures with distinc names you can interact with multiple active figures. To set a existing figure as your active, call figure(figHandle). New plots will go there now.

Max parallel http connections in a browser?

  1. Yes, wildcard domain will work for you.
  2. Not aware of any limits on connections. Limits if any will be browser specific.

How to replace comma (,) with a dot (.) using java

if(str.indexOf(",")!=-1) { str = str.replaceAll(",","."); }

or even better

str = str.replace(',', '.');

How do you remove duplicates from a list whilst preserving order?

A solution without using imported modules or sets:

text = "ask not what your country can do for you ask what you can do for your country"
sentence = text.split(" ")
noduplicates = [(sentence[i]) for i in range (0,len(sentence)) if sentence[i] not in sentence[:i]]
print(noduplicates)

Gives output:

['ask', 'not', 'what', 'your', 'country', 'can', 'do', 'for', 'you']

What is "406-Not Acceptable Response" in HTTP?

In my case, I added:

Content-Type: application/x-www-form-urlencoded

solved my problem completely.

Windows 7 SDK installation failure

You should really check the log. It seems that quite a few components can cause the Windows SDK installer to fail to install with this useless error message. For instance it could be the Visual C++ Redistributable Package as mentioned there.

Read/Write String from/to a File in Android

public static void writeStringAsFile(final String fileContents, String fileName) {
    Context context = App.instance.getApplicationContext();
    try {
        FileWriter out = new FileWriter(new File(context.getFilesDir(), fileName));
        out.write(fileContents);
        out.close();
    } catch (IOException e) {
        Logger.logError(TAG, e);
    }
}

public static String readFileAsString(String fileName) {
    Context context = App.instance.getApplicationContext();
    StringBuilder stringBuilder = new StringBuilder();
    String line;
    BufferedReader in = null;

    try {
        in = new BufferedReader(new FileReader(new File(context.getFilesDir(), fileName)));
        while ((line = in.readLine()) != null) stringBuilder.append(line);

    } catch (FileNotFoundException e) {
        Logger.logError(TAG, e);
    } catch (IOException e) {
        Logger.logError(TAG, e);
    } 

    return stringBuilder.toString();
}

How to create RecyclerView with multiple view type?

Create different ViewHolder for different layout

enter image description here
RecyclerView can have any number of viewholders you want but for better readability lets see how to create one with two ViewHolders.

It can be done in three simple steps

  1. Override public int getItemViewType(int position)
  2. Return different ViewHolders based on the ViewType in onCreateViewHolder() method
  3. Populate View based on the itemViewType in onBindViewHolder() method

Here is a small code snippet

public class YourListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

   private static final int LAYOUT_ONE= 0;
   private static final int LAYOUT_TWO= 1;

   @Override
   public int getItemViewType(int position)
   {
      if(position==0)
        return LAYOUT_ONE;
      else
        return LAYOUT_TWO;
   }

   @Override
   public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

      View view =null;
      RecyclerView.ViewHolder viewHolder = null;

      if(viewType==LAYOUT_ONE)
      {
          view = LayoutInflater.from(parent.getContext()).inflate(R.layout.one,parent,false);
          viewHolder = new ViewHolderOne(view);
      }
      else
      {
          view = LayoutInflater.from(parent.getContext()).inflate(R.layout.two,parent,false);
          viewHolder= new ViewHolderTwo(view);
      }

      return viewHolder;
   }

   @Override
   public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {

      if(holder.getItemViewType()== LAYOUT_ONE)
      {
            // Typecast Viewholder 
            // Set Viewholder properties 
            // Add any click listener if any 
      }
      else {

        ViewHolderOne vaultItemHolder = (ViewHolderOne) holder;
        vaultItemHolder.name.setText(displayText);
        vaultItemHolder.name.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
            .......
           }
         });

       }

   }

  //****************  VIEW HOLDER 1 ******************//

   public class ViewHolderOne extends RecyclerView.ViewHolder {

      public TextView name;

      public ViewHolderOne(View itemView) {
         super(itemView);
         name = (TextView)itemView.findViewById(R.id.displayName);
     }
   }


   //****************  VIEW HOLDER 2 ******************//

   public class ViewHolderTwo extends RecyclerView.ViewHolder{

      public ViewHolderTwo(View itemView) {
         super(itemView);

        ..... Do something
      }
   }
}

getItemViewType(int position) is the key

In my opinion,the starting point to create this kind of recyclerView is the knowledge of this method. Since this method is optional to override therefore it is not visible in RecylerView class by default which in turn makes many developers(including me) wonder where to begin. Once you know that this method exists, creating such RecyclerView would be a cakewalk.

Lets see one example to prove my point. If you want to show two layout at alternate positions do this

@Override
public int getItemViewType(int position)
{
   if(position%2==0)       // Even position 
     return LAYOUT_ONE;
   else                   // Odd position 
     return LAYOUT_TWO;
}

Relevant Links:

Check out the project where I have implemented this

Force “landscape” orientation mode

screen.orientation.lock('landscape');

Will force it to change to and stay in landscape mode. Tested on Nexus 5.

http://www.w3.org/TR/screen-orientation/#examples

How to declare a inline object with inline variables without a parent class

yes, there is:

object[] x = new object[2];

x[0] = new { firstName = "john", lastName = "walter" };
x[1] = new { brand = "BMW" };

you were practically there, just the declaration of the anonymous types was a little off.

Set min-width either by content or 200px (whichever is greater) together with max-width

The problem is that flex: 1 sets flex-basis: 0. Instead, you need

.container .box {
  min-width: 200px;
  max-width: 400px;
  flex-basis: auto; /* default value */
  flex-grow: 1;
}

_x000D_
_x000D_
.container {_x000D_
  display: -webkit-flex;_x000D_
  display: flex;_x000D_
  -webkit-flex-wrap: wrap;_x000D_
  flex-wrap: wrap;_x000D_
}_x000D_
_x000D_
.container .box {_x000D_
  -webkit-flex-grow: 1;_x000D_
  flex-grow: 1;_x000D_
  min-width: 100px;_x000D_
  max-width: 400px;_x000D_
  height: 200px;_x000D_
  background-color: #fafa00;_x000D_
  overflow: hidden;_x000D_
}
_x000D_
<div class="container">_x000D_
  <div class="box">_x000D_
    <table>_x000D_
      <tr>_x000D_
        <td>Content</td>_x000D_
        <td>Content</td>_x000D_
        <td>Content</td>_x000D_
      </tr>_x000D_
    </table>    _x000D_
  </div>_x000D_
  <div class="box">_x000D_
    <table>_x000D_
      <tr>_x000D_
        <td>Content</td>_x000D_
      </tr>_x000D_
    </table>    _x000D_
  </div>_x000D_
  <div class="box">_x000D_
    <table>_x000D_
      <tr>_x000D_
        <td>Content</td>_x000D_
        <td>Content</td>_x000D_
      </tr>_x000D_
    </table>    _x000D_
  </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Android java.lang.NoClassDefFoundError

Try going to Project -> Properties -> Java Build Path -> Order & Export And Confirm Android Private Libraries are checked for your project and for all other library projects you are using in your Application.

How can I switch to a tag/branch in hg?

Once you have cloned the repo, you have everything: you can then hg up branchname or hg up tagname to update your working copy.

UP: hg up is a shortcut of hg update, which also has hg checkout alias for people with git habits.

Including all the jars in a directory within the Java classpath

class from wepapp:

  > mvn clean install

  > java -cp "webapp/target/webapp-1.17.0-SNAPSHOT/WEB-INF/lib/tool-jar-1.17.0-SNAPSHOT.jar;webapp/target/webapp-1.17.0-SNAPSHOT/WEB-INF/lib/*" com.xx.xx.util.EncryptorUtils param1 param2

Create empty data frame with column names by assigning a string vector?

How about:

df <- data.frame(matrix(ncol = 3, nrow = 0))
x <- c("name", "age", "gender")
colnames(df) <- x

To do all these operations in one-liner:

setNames(data.frame(matrix(ncol = 3, nrow = 0)), c("name", "age", "gender"))

#[1] name   age    gender
#<0 rows> (or 0-length row.names)

Or

data.frame(matrix(ncol=3,nrow=0, dimnames=list(NULL, c("name", "age", "gender"))))

Add 10 seconds to a Date

// let timeObject = new Date();
// let milliseconds= 10 * 1000; // 10 seconds = 10000 milliseconds
timeObject = new Date(timeObject.getTime() + milliseconds);

How to check the input is an integer or not in Java?

Using Integer.parseIn(String), you can parse string value into integer. Also you need to catch exception in case if input string is not a proper number.

int x = 0;

try {       
    x = Integer.parseInt("100"); // Parse string into number
} catch (NumberFormatException e) {
    e.printStackTrace();
}

Convert string to hex-string in C#

For Unicode support:

public class HexadecimalEncoding
{
    public static string ToHexString(string str)
    {
        var sb = new StringBuilder();

        var bytes = Encoding.Unicode.GetBytes(str);
        foreach (var t in bytes)
        {
            sb.Append(t.ToString("X2"));
        }

        return sb.ToString(); // returns: "48656C6C6F20776F726C64" for "Hello world"
    }

    public static string FromHexString(string hexString)
    {
        var bytes = new byte[hexString.Length / 2];
        for (var i = 0; i < bytes.Length; i++)
        {
            bytes[i] = Convert.ToByte(hexString.Substring(i * 2, 2), 16);
        }

        return Encoding.Unicode.GetString(bytes); // returns: "Hello world" for "48656C6C6F20776F726C64"
    }
}

Android Transparent TextView?

try to set the transparency with the android-studio designer in activity_main.xml. If you want it to be transparent, write it for example like this for white: White: #FFFFFF, with 50% transparency: #80FFFFFF This is for Kotlin tho, not sure if that will work the same way for basic android (java).

Fastest way to remove first char in a String

You could profile it, if you really cared. Write a loop of many iterations and see what happens. Chances are, however, that this is not the bottleneck in your application, and TrimStart seems the most semantically correct. Strive to write code readably before optimizing.

Conversion of a datetime2 data type to a datetime data type results out-of-range value

Sometimes EF does not know that is dealing with a computed column or a trigger. By design, those operations will set a value outside of EF after an insert.

The fix is to specify Computed in EF's edmx for that column in the StoreGeneratedPattern property.

For me it was when the column had a trigger which inserted the current date and time, see below in the third section.


Steps To Resolve

In Visual Studio open the Model Browser page then Model then Entity Types -> then

  1. Select the entity and the date time property
  2. Select StoreGeneratedPattern
  3. Set to Computed

EF Model Browser Model Entity Type dialog


For this situation other answers are workarounds, for the purpose of the column is to have a time/date specified when the record was created, and that is SQL's job to execute a trigger to add the correct time. Such as this SQL trigger:

DEFAULT (GETDATE()) FOR [DateCreated].

offsetTop vs. jQuery.offset().top

This is what jQuery API Doc says about .offset():

Get the current coordinates of the first element, or set the coordinates of every element, in the set of matched elements, relative to the document.

This is what MDN Web API says about .offsetTop:

offsetTop returns the distance of the current element relative to the top of the offsetParent node

This is what jQuery v.1.11 .offset() basically do when getting the coords:

var box = { top: 0, left: 0 };

// BlackBerry 5, iOS 3 (original iPhone)
if ( typeof elem.getBoundingClientRect !== strundefined ) {
  box = elem.getBoundingClientRect();
}
win = getWindow( doc );
return {
  top: box.top  + ( win.pageYOffset || docElem.scrollTop )  - ( docElem.clientTop  || 0 ),
  left: box.left + ( win.pageXOffset || docElem.scrollLeft ) - ( docElem.clientLeft || 0 )
};
  • pageYOffset intuitively says how much was the page scrolled
  • docElem.scrollTop is the fallback for IE<9 (which are BTW unsupported in jQuery 2)
  • docElem.clientTop is the width of the top border of an element (the document in this case)
  • elem.getBoundingClientRect() gets the coords relative to the document viewport (see comments). It may return fraction values, so this is the source of your bug. It also may cause a bug in IE<8 when the page is zoomed. To avoid fraction values, try to calculate the position iteratively

Conclusion

  • If you want coords relative to the parent node, use element.offsetTop. Add element.scrollTop if you want to take the parent scrolling into account. (or use jQuery .position() if you are fan of that library)
  • If you want coords relative to the viewport use element.getBoundingClientRect().top. Add window.pageYOffset if you want to take the document scrolling into account. You don't need to subtract document's clientTop if the document has no border (usually it doesn't), so you have position relative to the document
  • Subtract element.clientTop if you don't consider the element border as the part of the element

Difference between File.separator and slash in paths

Late to the party. I'm on Windows 10 with JDK 1.8 and Eclipse MARS 1.
I find that

getClass().getClassLoader().getResourceAsStream("path/to/resource");

works and

getClass().getClassLoader().getResourceAsStream("path"+File.separator+"to"+File.separator+"resource");

does not work and

getClass().getClassLoader().getResourceAsStream("path\to\resource");

does not work. The last two are equivalent. So... I have good reason to NOT use File.separator.

ActionBar text color

These functions work well

In Java

private void setActionbarTextColor(ActionBar actBar, int color) {

    String title = actBar.getTitle().toString();
    Spannable spannablerTitle = new SpannableString(title);
    spannablerTitle.setSpan(new ForegroundColorSpan(color), 0, spannablerTitle.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
    actBar.setTitle(spannablerTitle);

}

then to use it just feed it your action bar and the new color i.e.

ActionBar actionBar = getActionBar();    // Or getSupportActionBar() if using appCompat
int red = Color.RED
setActionbarTextColor(actionBar, red);

In Kotlin

You can use an extension function like this:

private fun ActionBar.setTitleColor(color: Int) {
    val text = SpannableString(title ?: "")
    text.setSpan(ForegroundColorSpan(color),0,text.length, Spannable.SPAN_INCLUSIVE_INCLUSIVE)
    title = text
}

And then apply to your ActionBar with

actionBar?.setTitleColor(Color.RED)

Powershell v3 Invoke-WebRequest HTTPS error

Did you try using System.Net.WebClient?

$url = 'https://IPADDRESS/resource'
$wc = New-Object System.Net.WebClient
$wc.Credentials = New-Object System.Net.NetworkCredential("username","password")
$wc.DownloadString($url)

What exactly is RESTful programming?

A great book on REST is REST in Practice.

Must reads are Representational State Transfer (REST) and REST APIs must be hypertext-driven

See Martin Fowlers article the Richardson Maturity Model (RMM) for an explanation on what an RESTful service is.

Richardson Maturity Model

To be RESTful a Service needs to fulfill the Hypermedia as the Engine of Application State. (HATEOAS), that is, it needs to reach level 3 in the RMM, read the article for details or the slides from the qcon talk.

The HATEOAS constraint is an acronym for Hypermedia as the Engine of Application State. This principle is the key differentiator between a REST and most other forms of client server system.

...

A client of a RESTful application need only know a single fixed URL to access it. All future actions should be discoverable dynamically from hypermedia links included in the representations of the resources that are returned from that URL. Standardized media types are also expected to be understood by any client that might use a RESTful API. (From Wikipedia, the free encyclopedia)

REST Litmus Test for Web Frameworks is a similar maturity test for web frameworks.

Approaching pure REST: Learning to love HATEOAS is a good collection of links.

REST versus SOAP for the Public Cloud discusses the current levels of REST usage.

REST and versioning discusses Extensibility, Versioning, Evolvability, etc. through Modifiability

Resize image in the wiki of GitHub using Markdown

Updated:

Markdown syntax for images (external/internal):

![test](https://github.com/favicon.ico)

HTML code for sizing images (internal/external):

<img src="https://github.com/favicon.ico" width="48">

Example:

test


Old Answer:

This should work:

[[ http://url.to/image.png | height = 100px ]]

Source: https://guides.github.com/features/mastering-markdown/

Vertically align text to top within a UILabel

It can be done with more flexibility setting a height constraint to the label in Interface Builder, binding it to the code with an IBOutlet and changing that height to show the text in a concrete vertical position. Example for center and bottom alignment:

labelHeightConstraint.constant = centerAlignment ? 30 : 15
layoutIfNeeded()

Jquery UI datepicker. Disable array of Dates

If you want to disable particular date(s) in jquery datepicker then here is the simple demo for you.

<script type="text/javascript">
    var arrDisabledDates = {};
    arrDisabledDates[new Date("08/28/2017")] = new Date("08/28/2017");
    arrDisabledDates[new Date("12/23/2017")] = new Date("12/23/2017");
    $(".datepicker").datepicker({
        dateFormat: "dd/mm/yy",
        beforeShowDay: function (date) {
            var day = date.getDay(),
                    bDisable = arrDisabledDates[date];
            if (bDisable)
                return [false, "", ""]
        }
    });
</script>

javascript filter array multiple conditions

Using Array.Filter() with Arrow Functions we can achieve this using

users = users.filter(x => x.name == 'Mark' && x.address == 'England');

Here is the complete snippet

_x000D_
_x000D_
// initializing list of users_x000D_
var users = [{_x000D_
    name: 'John',_x000D_
    email: '[email protected]',_x000D_
    age: 25,_x000D_
    address: 'USA'_x000D_
  },_x000D_
  {_x000D_
    name: 'Tom',_x000D_
    email: '[email protected]',_x000D_
    age: 35,_x000D_
    address: 'England'_x000D_
  },_x000D_
  {_x000D_
    name: 'Mark',_x000D_
    email: '[email protected]',_x000D_
    age: 28,_x000D_
    address: 'England'_x000D_
  }_x000D_
];_x000D_
_x000D_
//filtering the users array and saving _x000D_
//result back in users variable_x000D_
users = users.filter(x => x.name == 'Mark' && x.address == 'England');_x000D_
_x000D_
_x000D_
//logging out the result in console_x000D_
console.log(users);
_x000D_
_x000D_
_x000D_

Transaction isolation levels relation with locks on table

I want to understand the lock each transaction isolation takes on the table

For example, you have 3 concurrent processes A, B and C. A starts a transaction, writes data and commit/rollback (depending on results). B just executes a SELECT statement to read data. C reads and updates data. All these process work on the same table T.

  • READ UNCOMMITTED - no lock on the table. You can read data in the table while writing on it. This means A writes data (uncommitted) and B can read this uncommitted data and use it (for any purpose). If A executes a rollback, B still has read the data and used it. This is the fastest but most insecure way to work with data since can lead to data holes in not physically related tables (yes, two tables can be logically but not physically related in real-world apps =\).
  • READ COMMITTED - lock on committed data. You can read the data that was only committed. This means A writes data and B can't read the data saved by A until A executes a commit. The problem here is that C can update data that was read and used on B and B client won't have the updated data.
  • REPEATABLE READ - lock on a block of SQL(which is selected by using select query). This means B reads the data under some condition i.e. WHERE aField > 10 AND aField < 20, A inserts data where aField value is between 10 and 20, then B reads the data again and get a different result.
  • SERIALIZABLE - lock on a full table(on which Select query is fired). This means, B reads the data and no other transaction can modify the data on the table. This is the most secure but slowest way to work with data. Also, since a simple read operation locks the table, this can lead to heavy problems on production: imagine that T table is an Invoice table, user X wants to know the invoices of the day and user Y wants to create a new invoice, so while X executes the read of the invoices, Y can't add a new invoice (and when it's about money, people get really mad, especially the bosses).

I want to understand where we define these isolation levels: only at JDBC/hibernate level or in DB also

Using JDBC, you define it using Connection#setTransactionIsolation.

Using Hibernate:

<property name="hibernate.connection.isolation">2</property>

Where

  • 1: READ UNCOMMITTED
  • 2: READ COMMITTED
  • 4: REPEATABLE READ
  • 8: SERIALIZABLE

Hibernate configuration is taken from here (sorry, it's in Spanish).

By the way, you can set the isolation level on RDBMS as well:

and on and on...

Mongoose: Get full list of users

This is just an Improvement of @soulcheck 's answer, and fix of the typo in forEach (missing closing bracket);

    server.get('/usersList', (req, res) => 
        User.find({}, (err, users) => 
            res.send(users.reduce((userMap, item) => {
                userMap[item.id] = item
                return userMap
            }, {}));
        );
    );

cheers!

Check, using jQuery, if an element is 'display:none' or block on click

Use this condition:

if (jQuery(".profile-page-cont").css('display') == 'block'){
    // Condition 
}

textarea character limit

Try using jQuery to avoid cross browser compatibility problems...

$("textarea").keyup(function(){
    if($(this).text().length > 500){
        var text = $(this).text();
        $(this).text(text.substr(0, 500));   
    }
});

Where is the correct location to put Log4j.properties in an Eclipse project?

In general I put it in a special folder "res" or "resources as already said, but after for the web application, I copy the log4j.properties with the ant task to the WEB-INF/classes directory. It is the same like letting the file at the root of the src/ folder but generally I prefer to see it in a dedicated folder.

With Maven, the usual place to put is in the folder src/main/resources as answered in this other post. All resources there will go to your build in the root classpath (e.g. target/classes/)

If you want a powerful logger, you can have also a look to slf4j library which is a logger facade and can use the log4j implementation behind.

Using a PHP variable in a text input value = statement

Solution

You are missing an echo. Each time that you want to show the value of a variable to HTML you need to echo it.

<input type="text" name="idtest" value="<?php echo $idtest; ?>" >

Note: Depending on the value, your echo is the function you use to escape it like htmlspecialchars.

What are Transient and Volatile Modifiers?

The volatile and transient modifiers can be applied to fields of classes1 irrespective of field type. Apart from that, they are unrelated.

The transient modifier tells the Java object serialization subsystem to exclude the field when serializing an instance of the class. When the object is then deserialized, the field will be initialized to the default value; i.e. null for a reference type, and zero or false for a primitive type. Note that the JLS (see 8.3.1.3) does not say what transient means, but defers to the Java Object Serialization Specification. Other serialization mechanisms may pay attention to a field's transient-ness. Or they may ignore it.

(Note that the JLS permits a static field to be declared as transient. This combination doesn't make sense for Java Object Serialization, since it doesn't serialize statics anyway. However, it could make sense in other contexts, so there is some justification for not forbidding it outright.)

The volatile modifier tells the JVM that writes to the field should always be synchronously flushed to memory, and that reads of the field should always read from memory. This means that fields marked as volatile can be safely accessed and updated in a multi-thread application without using native or standard library-based synchronization. Similarly, reads and writes to volatile fields are atomic. (This does not apply to >>non-volatile<< long or double fields, which may be subject to "word tearing" on some JVMs.) The relevant parts of the JLS are 8.3.1.4, 17.4 and 17.7.


1 - But not to local variables or parameters.

How to resolve symbolic links in a shell script

To work around the Mac incompatibility, I came up with

echo `php -r "echo realpath('foo');"`

Not great but cross OS

Convert js Array() to JSon object for use with JQuery .ajax

When using the data on the server, your characters can reach with the addition of slashes eg if string = {"hello"} comes as string = {\ "hello \"} to solve the following function can be used later to use json decode.

<?php
function stripslashes_deep($value)
{
    $value = is_array($value) ?
                array_map('stripslashes_deep', $value) :
                stripslashes($value);

    return $value;
}

$array = $_POST['jObject'];
$array = stripslashes_deep($array);

$data = json_decode($array, true);
print_r($data);
?>

How to Maximize a firefox browser window using Selenium WebDriver with node.js

First instantiate a firefox driver

WebDriver driver = new FirefoxDriver();

then maximize it

 driver.manage().window().maximize();

Get viewport/window height in ReactJS

Answers by @speckledcarp and @Jamesl are both brilliant. In my case, however, I needed a component whose height could extend the full window height, conditional at render time.... but calling a HOC within render() re-renders the entire subtree. BAAAD.

Plus, I wasn't interested in getting the values as props but simply wanted a parent div that would occupy the entire screen height (or width, or both).

So I wrote a Parent component providing a full height (and/or width) div. Boom.

A use case:

class MyPage extends React.Component {
  render() {
    const { data, ...rest } = this.props

    return data ? (
      // My app uses templates which misbehave badly if you manually mess around with the container height, so leave the height alone here.
      <div>Yay! render a page with some data. </div>
    ) : (
      <FullArea vertical>
        // You're now in a full height div, so containers will vertically justify properly
        <GridContainer justify="center" alignItems="center" style={{ height: "inherit" }}>
          <GridItem xs={12} sm={6}>
            Page loading!
          </GridItem>
        </GridContainer>
      </FullArea>
    )

Here's the component:

import React, { Component } from 'react'
import PropTypes from 'prop-types'

class FullArea extends Component {
  constructor(props) {
    super(props)
    this.state = {
      width: 0,
      height: 0,
    }
    this.getStyles = this.getStyles.bind(this)
    this.updateWindowDimensions = this.updateWindowDimensions.bind(this)
  }

  componentDidMount() {
    this.updateWindowDimensions()
    window.addEventListener('resize', this.updateWindowDimensions)
  }

  componentWillUnmount() {
    window.removeEventListener('resize', this.updateWindowDimensions)
  }

  getStyles(vertical, horizontal) {
    const styles = {}
    if (vertical) {
      styles.height = `${this.state.height}px`
    }
    if (horizontal) {
      styles.width = `${this.state.width}px`
    }
    return styles
  }

  updateWindowDimensions() {
    this.setState({ width: window.innerWidth, height: window.innerHeight })
  }

  render() {
    const { vertical, horizontal } = this.props
    return (
      <div style={this.getStyles(vertical, horizontal)} >
        {this.props.children}
      </div>
    )
  }
}

FullArea.defaultProps = {
  horizontal: false,
  vertical: false,
}

FullArea.propTypes = {
  horizontal: PropTypes.bool,
  vertical: PropTypes.bool,
}

export default FullArea

Python strip() multiple characters?

Because strip() only strips trailing and leading characters, based on what you provided. I suggest:

>>> import re
>>> name = "Barack (of Washington)"
>>> name = re.sub('[\(\)\{\}<>]', '', name)
>>> print(name)
Barack of Washington

What does \0 stand for?

To the C language, '\0' means exactly the same thing as the integer constant 0 (same value zero, same type int).

To someone reading the code, writing '\0' suggests that you're planning to use this particular zero as a character.

Difference between save and saveAndFlush in Spring data jpa

Depending on the hibernate flush mode that you are using (AUTO is the default) save may or may not write your changes to the DB straight away. When you call saveAndFlush you are enforcing the synchronization of your model state with the DB.

If you use flush mode AUTO and you are using your application to first save and then select the data again, you will not see a difference in bahvior between save() and saveAndFlush() because the select triggers a flush first. See the documention.

Is there a <meta> tag to turn off caching in all browsers?

Try using

    <META HTTP-EQUIV="Pragma" CONTENT="no-cache">
    <META HTTP-EQUIV="Expires" CONTENT="-1">

Catching FULL exception message

I keep coming back to these questions trying to figure out where exactly the data I'm interested in is buried in what is truly a monolithic ErrorRecord structure. Almost all answers give piecemeal instructions on how to pull certain bits of data.

But I've found it immensely helpful to dump the entire object with ConvertTo-Json so that I can visually see LITERALLY EVERYTHING in a comprehensible layout.

    try {
        Invoke-WebRequest...
    }
    catch {
        Write-Host ($_ | ConvertTo-Json)
    }

Use ConvertTo-Json's -Depth parameter to expand deeper values, but use extreme caution going past the default depth of 2 :P

https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/convertto-json

Sequence Permission in Oracle

To grant a permission:

grant select on schema_name.sequence_name to user_or_role_name;

To check which permissions have been granted

select * from all_tab_privs where TABLE_NAME = 'sequence_name'

linux script to kill java process

Use jps to list running java processes. The command returns the process id along with the main class. You can use kill command to kill the process with the returned id or use following one liner script.

kill $(jps | grep <MainClass> | awk '{print $1}')

MainClass is a class in your running java program which contains the main method.

How to remove pip package after deleting it manually

I'm sure there's a better way to achieve this and I would like to read about it, but a workaround I can think of is this:

  1. Install the package on a different machine.
  2. Copy the rm'ed directory to the original machine (ssh, ftp, whatever).
  3. pip uninstall the package (should work again then).

But, yes, I'd also love to hear about a decent solution for this situation.

Importing Pandas gives error AttributeError: module 'pandas' has no attribute 'core' in iPython Notebook

I had exact issue and here is how I fixed:

I found out that I had first installed Keras then installed pandas in my virtual env. When you install keras, pandas is shipped with it. Do not need to pip install pandas.

I tested this hypothesis by creating new virtual environment and wala... pandas appeared without me installing it. Thus I came to the conclusion that pandas is automatically installed when you pip install keras.

Could not find any resources appropriate for the specified culture or the neutral culture

I found that deleting the designer.cs file, excluding the resx file from the project and then re-including it often fixed this kind of issue, following a namespace refactoring (as per CFinck's answer)

How to change the application launcher icon on Flutter?

You have to replace the Flutter icon files with images of your own. This site will help you turn your png into launcher icons of various sizes:

https://romannurik.github.io/AndroidAssetStudio/icons-launcher.html

Clear text in EditText when entered

Also you can use code below

editText.getText().clear();

How to run a python script from IDLE interactive shell?

Try this

import os
import subprocess

DIR = os.path.join('C:\\', 'Users', 'Sergey', 'Desktop', 'helloword.py')

subprocess.call(['python', DIR])

Chrome: console.log, console.debug are not working

If you are seeing(3 messages are hidden by filters. Show all messages.) then click on show all message link in Chrome dev tool console.

Because if this option enabled by mistake the console.log("") message will show but this will in in hidden state.

Understanding .get() method in Python

I see this is a fairly old question, but this looks like one of those times when something's been written without knowledge of a language feature. The collections library exists to fulfill these purposes.

from collections import Counter
letter_counter = Counter()
for letter in 'The quick brown fox jumps over the lazy dog':
    letter_counter[letter] += 1

>>> letter_counter
Counter({' ': 8, 'o': 4, 'e': 3, 'h': 2, 'r': 2, 'u': 2, 'T': 1, 'a': 1, 'c': 1, 'b': 1, 'd': 1, 'g': 1, 'f': 1, 'i': 1, 'k': 1, 'j': 1, 'm': 1, 'l': 1, 'n': 1, 'q': 1, 'p': 1, 's': 1, 't': 1, 'w': 1, 'v': 1, 'y': 1, 'x': 1, 'z': 1})

In this example the spaces are being counted, obviously, but whether or not you want those filtered is up to you.

As for the dict.get(a_key, default_value), there have been several answers to this particular question -- this method returns the value of the key, or the default_value you supply. The first argument is the key you're looking for, the second argument is the default for when that key is not present.

Entity Framework Code First - two Foreign Keys from same table

InverseProperty in EF Core makes the solution easy and clean.

InverseProperty

So the desired solution would be:

public class Team
{
    [Key]
    public int TeamId { get; set;} 
    public string Name { get; set; }

    [InverseProperty(nameof(Match.HomeTeam))]
    public ICollection<Match> HomeMatches{ get; set; }

    [InverseProperty(nameof(Match.GuestTeam))]
    public ICollection<Match> AwayMatches{ get; set; }
}


public class Match
{
    [Key]
    public int MatchId { get; set; }

    [ForeignKey(nameof(HomeTeam)), Column(Order = 0)]
    public int HomeTeamId { get; set; }
    [ForeignKey(nameof(GuestTeam)), Column(Order = 1)]
    public int GuestTeamId { get; set; }

    public float HomePoints { get; set; }
    public float GuestPoints { get; set; }
    public DateTime Date { get; set; }

    public Team HomeTeam { get; set; }
    public Team GuestTeam { get; set; }
}

How to save Excel Workbook to Desktop regardless of user?

You've mentioned that they each have their own machines, but if they need to log onto a co-workers machine, and then use the file, saving it through "C:\Users\Public\Desktop\" will make it available to different usernames.

Public Sub SaveToDesktop()
    ThisWorkbook.SaveAs Filename:="C:\Users\Public\Desktop\" & ThisWorkbook.Name & "_copy", _ 
    FileFormat:=xlOpenXMLWorkbookMacroEnabled
End Sub

I'm not sure whether this would be a requirement, but may help!

How to avoid 'undefined index' errors?

You could try using a nice little function that will return the value if it exists or an empty string if not. This is what I use:

function arrayValueForKey($arrayName, $key) {
   if (isset($GLOBALS[$arrayName]) && isset($GLOBALS[$arrayName][$key])) {
      return $GLOBALS[$variable][$key];
   } else {
      return '';
   }
}

Then you can use it like this:

echo ' Values: ' . arrayValueForKey('output', 'admin_link') 
                 . arrayValueForKey('output', 'update_frequency');

And it won't throw up any errors!

Hope this helps!

Printing prime numbers from 1 through 100

To find whether no. is prime or not C++:

#include<iostream>
#include<cmath>

using namespace std;
int main(){

int n, counter=0;

cout <<"Enter a number to check whether it is prime or not \n";
cin>>n;

  for(int i=2; i<=n-1;i++) {
    if (n%i==0) {
      cout<<n<<" is NOT a prime number \n";
      break;
    }
    counter++;
                }
    //cout<<"Value n is "<<n<<endl;
    //cout << "number of times counter run is "<<counter << endl;
    if (counter == n-2)
      cout << n<< " is prime \n";
   return 0;
}

How do I add multiple conditions to "ng-disabled"?

You can try something like this.

<button class="button" ng-disabled="(!data.var1 && !data.var2) ? false : true">
</button>

Its working fine for me.

Efficient Algorithm for Bit Reversal (from MSB->LSB to LSB->MSB) in C

Efficient can mean throughput or latency.

For throughout, see the answer by Anders Cedronius, it’s a good one.

For lower latency, I would recommend this code:

uint32_t reverseBits( uint32_t x )
{
#if defined(__arm__) || defined(__aarch64__)
    __asm__( "rbit %0, %1" : "=r" ( x ) : "r" ( x ) );
    return x;
#endif
    // Flip pairwise
    x = ( ( x & 0x55555555 ) << 1 ) | ( ( x & 0xAAAAAAAA ) >> 1 );
    // Flip pairs
    x = ( ( x & 0x33333333 ) << 2 ) | ( ( x & 0xCCCCCCCC ) >> 2 );
    // Flip nibbles
    x = ( ( x & 0x0F0F0F0F ) << 4 ) | ( ( x & 0xF0F0F0F0 ) >> 4 );

    // Flip bytes. CPUs have an instruction for that, pretty fast one.
#ifdef _MSC_VER
    return _byteswap_ulong( x );
#elif defined(__INTEL_COMPILER)
    return (uint32_t)_bswap( (int)x );
#else
    // Assuming gcc or clang
    return __builtin_bswap32( x );
#endif
}

Compilers output: https://godbolt.org/z/5ehd89

Changing :hover to touch/click for mobile devices

I got the same trouble, in mobile device with Microsoft's Edge browser. I can solve the problem with: aria-haspopup="true". It need to add to the div and the :hover, :active, :focus for the other mobile browsers.

Example html:

<div class="left_bar" aria-haspopup="true">

CSS:

.left_bar:hover, .left_bar:focus, .left_bar:active{
    left: 0%;
    }

Get min and max value in PHP Array

How about without using predefined function like min or max ?

$arr = [4,5,6,7,8,2,9,1];
$val = $arr[0];
$n = count($arr);

for($i=1;$i<$n;$i++) {
if($val<$arr[$i]) {
    $val = $val;        
} else {
    $val = $arr[$i];
}
}
print($val);

?>

Kendo grid date column not formatting

I found this piece of information and got it to work correctly. The data given to me was in string format so I needed to parse the string using kendo.parseDate before formatting it with kendo.toString.

columns: [
    {
        field: "FirstName",
        title: "FIRST NAME"
    },
    {
        field: "LastName",
        title: "LAST NAME"
    },
    {
        field: "DateOfBirth",
        title: "DATE OF BIRTH",
        template: "#= kendo.toString(kendo.parseDate(DateOfBirth, 'yyyy-MM-dd'), 'MM/dd/yyyy') #"
    },
...


References:

  1. format-date-in-grid
  2. jsfiddle
  3. kendo ui date formatting

Using HTTPS with REST in Java

Check this out: http://code.google.com/p/resting/. I could use resting to consume HTTPS REST services.

How do I calculate a trendline for a graph?

If you have access to Excel, look in the "Statistical Functions" section of the Function Reference within Help. For straight-line best-fit, you need SLOPE and INTERCEPT and the equations are right there.

Oh, hang on, they're also defined online here: http://office.microsoft.com/en-us/excel/HP052092641033.aspx for SLOPE, and there's a link to INTERCEPT. OF course, that assumes MS don't move the page, in which case try Googling for something like "SLOPE INTERCEPT EQUATION Excel site:microsoft.com" - the link given turned out third just now.

Best /Fastest way to read an Excel Sheet into a DataTable?

public DataTable ImportExceltoDatatable(string filepath)
{
    // string sqlquery= "Select * From [SheetName$] Where YourCondition";
    string sqlquery = "Select * From [SheetName$] Where Id='ID_007'";
    DataSet ds = new DataSet();
    string constring = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + filepath + ";Extended Properties=\"Excel 12.0;HDR=YES;\"";
    OleDbConnection con = new OleDbConnection(constring + "");
    OleDbDataAdapter da = new OleDbDataAdapter(sqlquery, con);
    da.Fill(ds);
    DataTable dt = ds.Tables[0];
    return dt;
}

How to set the From email address for mailx command?

In case you also want to include your real name in the from-field, you can use the following format

mailx -r "[email protected] (My Name)" -s "My Subject" ...

If you happen to have non-ASCII characters in you name, like My AEÆoeøaaå (Æ= C3 86, ø= C3 B8, å= C3 A5), you have to encode them like this:

mailx -r "[email protected] (My =?utf-8?Q?AE=C3=86oe=C3=B8aa=C3=A5?=)" -s "My Subject" ...

Hope this can save someone an hour of hard work/research!

use "netsh wlan set hostednetwork ..." to create a wifi hotspot and the authentication can't work correctly

I had a similar problem and I solved it by setting a static IP on the Android device.

When you add the network on Android, first you enter the SSID and password, then underneath you can open advanced options and set a static IP.

Android textview usage as label and value

You can use <LinearLayout> to group elements horizontaly. Also you should use style to set margins, background and other properties. This will allow you not to repeat code for every label you use. Here is an example:

<LinearLayout
                    style="@style/FormItem"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:orientation="horizontal">
                <TextView
                        style="@style/FormLabel"
                        android:layout_width="wrap_content"
                        android:layout_height="@dimen/default_element_height"
                        android:text="@string/name_label"
                        />

                <EditText
                        style="@style/FormText.Editable"
                        android:id="@+id/cardholderName"
                        android:layout_width="wrap_content"
                        android:layout_height="@dimen/default_element_height"
                        android:layout_weight="1"
                        android:gravity="right|center_vertical"
                        android:hint="@string/card_name_hint"
                        android:imeOptions="actionNext"
                        android:singleLine="true"
                        />
            </LinearLayout>

Also you can create a custom view base on the layout above. Have you looked at Creating custom view ?

Remove privileges from MySQL database

The USAGE-privilege in mysql simply means that there are no privileges for the user 'phpadmin'@'localhost' defined on global level *.*. Additionally the same user has ALL-privilege on database phpmyadmin phpadmin.*.

So if you want to remove all the privileges and start totally from scratch do the following:

  • Revoke all privileges on database level:

    REVOKE ALL PRIVILEGES ON phpmyadmin.* FROM 'phpmyadmin'@'localhost';

  • Drop the user 'phpmyadmin'@'localhost'

    DROP USER 'phpmyadmin'@'localhost';

Above procedure will entirely remove the user from your instance, this means you can recreate him from scratch.

To give you a bit background on what described above: as soon as you create a user the mysql.user table will be populated. If you look on a record in it, you will see the user and all privileges set to 'N'. If you do a show grants for 'phpmyadmin'@'localhost'; you will see, the allready familliar, output above. Simply translated to "no privileges on global level for the user". Now your grant ALL to this user on database level, this will be stored in the table mysql.db. If you do a SELECT * FROM mysql.db WHERE db = 'nameofdb'; you will see a 'Y' on every priv.

Above described shows the scenario you have on your db at the present. So having a user that only has USAGE privilege means, that this user can connect, but besides of SHOW GLOBAL VARIABLES; SHOW GLOBAL STATUS; he has no other privileges.

What's the difference between "super()" and "super(props)" in React when using es6 classes?

Dan Abramov wrote an article on this topic:

Why Do We Write super(props)?

And the gist of it is that it's helpful to have a habit of passing it to avoid this scenario, that honestly, I don't see it unlikely to happen:

// Inside React
class Component {
  constructor(props) {
    this.props = props;
    // ...
  }
}

// Inside your code
class Button extends React.Component {
  constructor(props) {
    super(); //  We forgot to pass props
    console.log(props);      // ? {}
    console.log(this.props); //  undefined 
  }
  // ...
}

Inserting a value into all possible locations in a list

You could do this with the following list comprehension:

[mylist[i:] + [newelement] + mylist[:i] for i in xrange(len(mylist),-1,-1)]

With your example:

>>> mylist=['A','B']
>>> newelement='X'
>>> [mylist[i:] + [newelement] + mylist[:i] for i in xrange(len(mylist),-1,-1)]
[['X', 'A', 'B'], ['B', 'X', 'A'], ['A', 'B', 'X']]

Link error "undefined reference to `__gxx_personality_v0'" and g++

It sounds like you're trying to link with your resulting object file with gcc instead of g++:

Note that programs using C++ object files must always be linked with g++, in order to supply the appropriate C++ libraries. Attempting to link a C++ object file with the C compiler gcc will cause "undefined reference" errors for C++ standard library functions:

$ g++ -Wall -c hello.cc
$ gcc hello.o       (should use g++)
hello.o: In function `main':
hello.o(.text+0x1b): undefined reference to `std::cout'
.....
hello.o(.eh_frame+0x11):
  undefined reference to `__gxx_personality_v0'

Source: An Introduction to GCC - for the GNU compilers gcc and g++

Making a WinForms TextBox behave like your browser's address bar

This is working for me in .NET 2005 -

    ' * if the mouse button is down, do not run the select all.
    If MouseButtons = Windows.Forms.MouseButtons.Left Then
        Exit Sub
    End If

 ' * OTHERWISE INVOKE THE SELECT ALL AS DISCUSSED.

Remove non-ascii character in string

You can use the following regex to replace non-ASCII characters

str = str.replace(/[^A-Za-z 0-9 \.,\?""!@#\$%\^&\*\(\)-_=\+;:<>\/\\\|\}\{\[\]`~]*/g, '')

However, note that spaces, colons and commas are all valid ASCII, so the result will be

> str
"INFO] :, , ,  (Higashikurume)"

How to check if internet connection is present in Java?

You can simply write like this

import java.net.InetAddress;
import java.net.UnknownHostException;

public class Main {

    private static final String HOST = "localhost";

    public static void main(String[] args) throws UnknownHostException {

        boolean isConnected = !HOST.equals(InetAddress.getLocalHost().getHostAddress().toString());

        if (isConnected) System.out.println("Connected");
        else System.out.println("Not connected");

    }
}

What does 'var that = this;' mean in JavaScript?

Sometimes this can refer to another scope and refer to something else, for example suppose you want to call a constructor method inside a DOM event, in this case this will refer to the DOM element not the created object.

HTML

<button id="button">Alert Name</button>

JS

var Person = function(name) {
  this.name = name;
  var that = this;
  this.sayHi = function() {
    alert(that.name);
  };
};

var ahmad = new Person('Ahmad');
var element = document.getElementById('button');
element.addEventListener('click', ahmad.sayHi); // => Ahmad

Demo

The solution above will assing this to that then we can and access the name property inside the sayHi method from that, so this can be called without issues inside the DOM call.

Another solution is to assign an empty that object and add properties and methods to it and then return it. But with this solution you lost the prototype of the constructor.

var Person = function(name) {
  var that = {};
  that.name = name;
  that.sayHi = function() {
    alert(that.name);
  };
  return that;
};

Run a .bat file using python code

This has already been answered in detail on SO. Check out this thread, It should answer all your questions: Executing a subprocess fails

I've tried it myself with this code:

batchtest.py

from subprocess import Popen
p = Popen("batch.bat", cwd=r"C:\Path\to\batchfolder")
stdout, stderr = p.communicate()

batch.bat

echo Hello World!
pause

I've got the batchtest.py example from the aforementioned thread.

Android Studio Gradle: Error:Execution failed for task ':app:processDebugGoogleServices'. > No matching client found for package

if you run the other type of build(for example sign apk or etc), you must select app type of build then run the projects.

please seen the following image. for run this project we must select "app" in run configuration popup. enter image description here

Promise Error: Objects are not valid as a React child

You can't just return an array of objects because there's nothing telling React how to render that. You'll need to return an array of components or elements like:

render: function() {
  return (
    <span>
      // This will go through all the elements in arrayFromJson and
      // render each one as a <SomeComponent /> with data from the object
      {this.state.arrayFromJson.map(function(object) {
        return (
          <SomeComponent key={object.id} data={object} />
        );
      })}
    </span>
  );
}

Is there a sleep function in JavaScript?

If you are looking to block the execution of code with call to sleep, then no, there is no method for that in JavaScript.

JavaScript does have setTimeout method. setTimeout will let you defer execution of a function for x milliseconds.

setTimeout(myFunction, 3000);

// if you have defined a function named myFunction 
// it will run after 3 seconds (3000 milliseconds)

Remember, this is completely different from how sleep method, if it existed, would behave.

function test1()
{    
    // let's say JavaScript did have a sleep function..
    // sleep for 3 seconds
    sleep(3000);

    alert('hi'); 
}

If you run the above function, you will have to wait for 3 seconds (sleep method call is blocking) before you see the alert 'hi'. Unfortunately, there is no sleep function like that in JavaScript.

function test2()
{
    // defer the execution of anonymous function for 
    // 3 seconds and go to next line of code.
    setTimeout(function(){ 

        alert('hello');
    }, 3000);  

    alert('hi');
}

If you run test2, you will see 'hi' right away (setTimeout is non blocking) and after 3 seconds you will see the alert 'hello'.

Formatting code in Notepad++

If you go to TextFX menu and go to TextFX Edit, you will see a menu item Reindent C++ Code.

That will also format C# code.

PHP Warning: POST Content-Length of 8978294 bytes exceeds the limit of 8388608 bytes in Unknown on line 0

Go to

C:\drive\xampp(where xampp installed)

simply find php.ini file then in the file search

post_max_size=XXM
upload_max_size=XXM

Change with this code

post_max_size=100M
upload_max_filesize=100M

Don't forget to restart the xampp

How to add icon inside EditText view in Android ?

Use :

<EditText
    ..     
    android:drawableStart="@drawable/icon" />

No Exception while type casting with a null in java

This is by design. You can cast null to any reference type. Otherwise you wouldn't be able to assign it to reference variables.

executing a function in sql plus

declare
  x number;
begin
  x := myfunc(myargs);
end;

Alternatively:

select myfunc(myargs) from dual;

php implode (101) with quotes

Don't know if it's quicker, but, you could save a line of code with your method:

From

$array = array('lastname', 'email', 'phone');
$comma_separated = implode("','", $array);
$comma_separated = "'".$comma_separated."'";

To:

$array = array('lastname', 'email', 'phone');
$comma_separated = "'".implode("','", $array)."'";

How to use a ViewBag to create a dropdownlist?

Use Viewbag is wrong for sending list to view.You should using Viewmodel in this case. like this:

Send Country list and City list and Other list you need to show in View:

HomeController Code:

[HttpGet]
        public ActionResult NewAgahi() // New Advertising
        {
            //--------------------------------------------------------
            // ??????? ?? ?????? ???? ????? ??? ??? ?? ???
            Country_Repository blCountry = new Country_Repository();
            Ostan_Repository blOstan = new Ostan_Repository();
            City_Repository blCity = new City_Repository();
            Mahale_Repository blMahale = new Mahale_Repository();
            Agahi_Repository blAgahi = new Agahi_Repository();

            var vm = new NewAgahi_ViewModel();
            vm.Country = blCountry.Select();
            vm.Ostan = blOstan.Select();
            vm.City = blCity.Select();
            vm.Mahale = blMahale.Select();
            //vm.Agahi = blAgahi.Select();

            return View(vm);
        }

        [ValidateAntiForgeryToken]
        [HttpPost]
        public ActionResult NewAgahi(Agahi agahi)
        {

            if (ModelState.IsValid == true)
            {
                Agahi_Repository blAgahi = new Agahi_Repository();

                agahi.Date = DateTime.Now.Date;
                agahi.UserId = 1048;
                agahi.GroupId = 1;


                if (blAgahi.Add(agahi) == true)
                {
                    //Success
                    return JavaScript("alert('??? ??')");

                }
                else
                {
                    //Fail
                    return JavaScript("alert('????? ?? ???')");

            }

Viewmodel Code:

using ProjectName.Models.DomainModels;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace ProjectName.ViewModels
{
    public class NewAgahi_ViewModel // ???? ??????? ???? ?? ??? ??? ?? ?? ???
    { 

        public IEnumerable<Country> Country { get; set; }

        public IEnumerable<Ostan> Ostan { get; set; }

        public IEnumerable<City> City { get; set; }

        public IQueryable<Mahale> Mahale { get; set; }

        public ProjectName.Models.DomainModels.Agahi Agahi { get; set; }

    }
}

View Code:

@model ProjectName.ViewModels.NewAgahi_ViewModel

..... .....

@Html.DropDownList("CountryList", new SelectList(Model.Country, "id", "Name"))

 @Html.DropDownList("CityList", new SelectList(Model.City, "id", "Name"))

Country_Repository Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using ProjectName.Models.DomainModels;

namespace ProjectName.Models.Repositories
{
    public class Country_Repository : IDisposable
    {
        private MyWebSiteDBEntities db = null;


        public Country_Repository()
        {
            db = new DomainModels.MyWebSiteDBEntities();
        }

        public Boolean Add(Country entity, bool autoSave = true)
        {
            try
            {
                db.Country.Add(entity);
                if (autoSave)
                    return Convert.ToBoolean(db.SaveChanges()); 
                                                                //return "True";
                else
                    return false;
            }
            catch (Exception e)
            {
                string ss = e.Message;
                //return e.Message;
                return false;
            }
        }


        public bool Update(Country entity, bool autoSave = true)
        {
            try
            {
                db.Country.Attach(entity);
                db.Entry(entity).State = System.Data.Entity.EntityState.Modified;
                if (autoSave)
                    return Convert.ToBoolean(db.SaveChanges());
                else
                    return false;
            }
            catch (Exception e)
            {
                string ss = e.Message; // ?? ?????????? ??? ???? ?????? ?????? ??? ?? ?????

                return false;
            }
        }

        public bool Delete(Country entity, bool autoSave = true)
        {
            try
            {
                db.Entry(entity).State = System.Data.Entity.EntityState.Deleted;
                if (autoSave)
                    return Convert.ToBoolean(db.SaveChanges());
                else
                    return false;
            }
            catch
            {
                return false;
            }
        }

        public bool Delete(int id, bool autoSave = true)
        {
            try
            {
                var entity = db.Country.Find(id);
                db.Entry(entity).State = System.Data.Entity.EntityState.Deleted;
                if (autoSave)
                    return Convert.ToBoolean(db.SaveChanges());
                else
                    return false;
            }
            catch
            {
                return false;
            }
        }

        public Country Find(int id)
        {
            try
            {
                return db.Country.Find(id);
            }
            catch
            {
                return null;
            }
        }


        public IQueryable<Country> Where(System.Linq.Expressions.Expression<Func<Country, bool>> predicate)
        {
            try
            {
                return db.Country.Where(predicate);
            }
            catch
            {
                return null;
            }
        }

        public IQueryable<Country> Select()
        {
            try
            {
                return db.Country.AsQueryable();
            }
            catch
            {
                return null;
            }
        }

        public IQueryable<TResult> Select<TResult>(System.Linq.Expressions.Expression<Func<Country, TResult>> selector)
        {
            try
            {
                return db.Country.Select(selector);
            }
            catch
            {
                return null;
            }
        }

        public int GetLastIdentity()
        {
            try
            {
                if (db.Country.Any())
                    return db.Country.OrderByDescending(p => p.id).First().id;
                else
                    return 0;
            }
            catch
            {
                return -1;
            }
        }

        public int Save()
        {
            try
            {
                return db.SaveChanges();
            }
            catch
            {
                return -1;
            }
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (this.db != null)
                {
                    this.db.Dispose();
                    this.db = null;
                }
            }
        }

        ~Country_Repository()
        {
            Dispose(false);
        }
    }
}

Invariant Violation: Could not find "store" in either the context or props of "Connect(SportsDatabase)"

in my case just

const myReducers = combineReducers({
  user: UserReducer
});

const store: any = createStore(
  myReducers,
  applyMiddleware(thunk)
);

shallow(<Login />, { context: { store } });

C# equivalent of C++ vector, with contiguous memory?

You could use a List<T> and when T is a value type it will be allocated in contiguous memory which would not be the case if T is a reference type.

Example:

List<int> integers = new List<int>();
integers.Add(1);
integers.Add(4);
integers.Add(7);

int someElement = integers[1];

Java String to Date object of the format "yyyy-mm-dd HH:mm:ss"

For future reference:

 yyyy => 4 digit year
 MM   => 2 digit month (you must type MM in ALL CAPS)
 dd   => 2 digit "day of the month"

 HH   => 2-digit "hour in day" (0 to 23)
 mm   => 2-digit minute (you must type mm in lowercase)
 ss   => 2-digit seconds
 SSS  => milliseconds

So "yyyy-MM-dd HH:mm:ss" returns "2018-01-05 09:49:32"

But "MMM dd, yyyy hh:mm a" returns "Jan 05, 2018 09:49 am"

The so-called examples at https://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html show only output. They do not tell you what formats to use!

Subset data.frame by date

The first thing you should do with date variables is confirm that R reads it as a Date. To do this, for the variable (i.e. vector/column) called Date, in the data frame called EPL2011_12, input

class(EPL2011_12$Date)

The output should read [1] "Date". If it doesn't, you should format it as a date by inputting

EPL2011_12$Date <- as.Date(EPL2011_12$Date, "%d-%m-%y")

Note that the hyphens in the date format ("%d-%m-%y") above can also be slashes ("%d/%m/%y"). Confirm that R sees it as a Date. If it doesn't, try a different formatting command

EPL2011_12$Date <- format(EPL2011_12$Date, format="%d/%m/%y")

Once you have it in Date format, you can use the subset command, or you can use brackets

WhateverYouWant <- EPL2011_12[EPL2011_12$Date > as.Date("2014-12-15"),]

How to correctly close a feature branch in Mercurial?

One way is to just leave merged feature branches open (and inactive):

$ hg up default
$ hg merge feature-x
$ hg ci -m merge

$ hg heads
    (1 head)

$ hg branches
default    43:...
feature-x  41:...
    (2 branches)

$ hg branches -a
default    43:...
    (1 branch)

Another way is to close a feature branch before merging using an extra commit:

$ hg up feature-x
$ hg ci -m 'Closed branch feature-x' --close-branch
$ hg up default
$ hg merge feature-x
$ hg ci -m merge

$ hg heads
    (1 head)

$ hg branches
default    43:...
    (1 branch)

The first one is simpler, but it leaves an open branch. The second one leaves no open heads/branches, but it requires one more auxiliary commit. One may combine the last actual commit to the feature branch with this extra commit using --close-branch, but one should know in advance which commit will be the last one.

Update: Since Mercurial 1.5 you can close the branch at any time so it will not appear in both hg branches and hg heads anymore. The only thing that could possibly annoy you is that technically the revision graph will still have one more revision without childen.

Update 2: Since Mercurial 1.8 bookmarks have become a core feature of Mercurial. Bookmarks are more convenient for branching than named branches. See also this question:

How to iterate over the file in python

Just use for x in f: ..., this gives you line after line, is much shorter and readable (partly because it automatically stops when the file ends) and also saves you the rstrip call because the trailing newline is already stipped.

The error is caused by the exit condition, which can never be true: Even if the file is exhausted, readline will return an empty string, not None. Also note that you could still run into trouble with empty lines, e.g. at the end of the file. Adding if line.strip() == "": continue makes the code ignore blank lines, which is propably a good thing anyway.

Determine the line of code that causes a segmentation fault?

Lucas's answer about core dumps is good. In my .cshrc I have:

alias core 'ls -lt core; echo where | gdb -core=core -silent; echo "\n"'

to display the backtrace by entering 'core'. And the date stamp, to ensure I am looking at the right file :(.

Added: If there is a stack corruption bug, then the backtrace applied to the core dump is often garbage. In this case, running the program within gdb can give better results, as per the accepted answer (assuming the fault is easily reproducible). And also beware of multiple processes dumping core simultaneously; some OS's add the PID to the name of the core file.

WPF ListView - detect when selected item is clicked

I would also suggest deselecting an item after it has been clicked and use the MouseDoubleClick event

private void listBox_MouseDoubleClick(object sender, MouseButtonEventArgs e)
{
    try {
        //Do your stuff here
        listBox.SelectedItem = null;
        listBox.SelectedIndex = -1;
    } catch (Exception ex) {
        System.Diagnostics.Debug.WriteLine(ex.Message);
    }
}

Write to .txt file?

FILE *fp;
char* str = "string";
int x = 10;

fp=fopen("test.txt", "w");
if(fp == NULL)
    exit(-1);
fprintf(fp, "This is a string which is written to a file\n");
fprintf(fp, "The string has %d words and keyword %s\n", x, str);
fclose(fp);

Converting unix time into date-time via excel

TLDR

=(A1/86400)+25569

...and the format of the cell should be date.

If it doesn't work for you

  • If you get a number you forgot to format the output cell as a date.
  • If you get ##### you probably don't have a real Unix time. Check your timestamps in https://www.epochconverter.com/. Try to divide your input by 10, 100, 1000 or 10000**
  • You work with timestamps outside Excel's (very extended) limits.
  • You didn't replace A1 with the cell containing the timestamp ;-p

Explanation

Unix system represent a point in time as a number. Specifically the number of seconds* since a zero-time called the Unix epoch which is 1/1/1970 00:00 UTC/GMT. This number of seconds is called "Unix timestamp" or "Unix time" or "POSIX time" or just "timestamp" and sometimes (confusingly) "Unix epoch".

In the case of Excel they chose a different zero-time and step (because who wouldn't like variety in technical details?). So Excel counts days since 24 hours before 1/1/0000 UTC/GMT. So 25569 corresponds to 1/1/1970 00:00 UTC/GMT and 25570 to 2/1/1970 00:00.

Now please note that we have 86400 seconds per day (24 hours x60 minutes each x60 seconds) and you can understand what this formula does: A1/86400 converts seconds to days and +25569 adjusts for the offset between what is time-zero for Unix and what is time-zero for Excel.

By the way DATE(1970,1,1) will helpfully return 25569 for you in case you forget all this so a more "self-documenting" way to write our formula is:

=A1/(24*60*60) + DATE(1970,1,1)

P.S.: All these were already present in other answers and comments just not laid out as I like them and I don't feel it's OK to edit the hell out of another answer.


*: that's almost correct because you should not count leap seconds

**: E.g. in the case of this question the number was number of milliseconds since the the Unix epoch.

Is there any publicly accessible JSON data source to test with real world data?

Found one from Flickr that doesn't need registration / api.

Basic sample, Fiddle: http://jsfiddle.net/Braulio/vDr36/

More info: post

Pasted sample

HTML

<div id="images">

</div>

Javascript

// Querystring, "tags" search term, comma delimited
var query = "http://www.flickr.com/services/feeds/photos_public.gne?tags=soccer&format=json&jsoncallback=?";


// This function is called once the call is satisfied
// http://stackoverflow.com/questions/13854250/understanding-cross-domain-xhr-and-xml-data
var mycallback = function (data) {

    // Start putting together the HTML string
    var htmlString = "";

    // Now start cycling through our array of Flickr photo details
    $.each(data.items, function(i,item){

        // I only want the ickle square thumbnails
        var sourceSquare = (item.media.m).replace("_m.jpg", "_s.jpg");

        // Here's where we piece together the HTML
        htmlString += '<li><a href="' + item.link + '" target="_blank">';
        htmlString += '<img title="' + item.title + '" src="' + sourceSquare;
        htmlString += '" alt="'; htmlString += item.title + '" />';
        htmlString += '</a></li>';

    });

    // Pop our HTML in the #images DIV
    $('#images').html(htmlString);
};


// Ajax call to retrieve data
$.getJSON(query, mycallback);

Another very interesting is Star Wars Rest API:

https://swapi.co/

System.Data.OracleClient requires Oracle client software version 8.1.7

Oracle Client version 11 cannot connect to 8i databases. You will need a client in version 10 at most.

The type is defined in an assembly that is not referenced, how to find the cause?

I have a similar problem, and I remove the RuntimeFrameworkVersion, and the problem was fixed.

Try to remove 1.1.1 or

System.Threading.Timer in C# it seems to be not working. It runs very fast every 3 second

Is using System.Threading.Timer mandatory?

If not, System.Timers.Timer has handy Start() and Stop() methods (and an AutoReset property you can set to false, so that the Stop() is not needed and you simply call Start() after executing).

Android - Pulling SQlite database android device

If you want your database file

See the DDMS > File explore

find your db file from your package name

then Click on pull a file from device (Rooted device only)

Is __init__.py not required for packages in Python 3.3+

I would say that one should omit the __init__.py only if one wants to have the implicit namespace package. If you don't know what it means, you probably don't want it and therefore you should continue to use the __init__.py even in Python 3.

When to use static classes in C#

I do tend to use static classes for factories. For example, this is the logging class in one of my projects:

public static class Log
{
   private static readonly ILoggerFactory _loggerFactory =
      IoC.Resolve<ILoggerFactory>();

   public static ILogger For<T>(T instance)
   {
      return For(typeof(T));
   }

   public static ILogger For(Type type)
   {
      return _loggerFactory.GetLoggerFor(type);
   }
}

You might have even noticed that IoC is called with a static accessor. Most of the time for me, if you can call static methods on a class, that's all you can do so I mark the class as static for extra clarity.

Eclipse: The resource is not on the build path of a Java project

You can add the src folder to build path by:

  1. Select Java perspective.
  2. Right click on src folder.
  3. Select Build Path > Use a source folder.

And you are done. Hope this help.

EDIT: Refer to the Eclipse documentation

select a value where it doesn't exist in another table

This would select 4 in your case

SELECT ID FROM TableA WHERE ID NOT IN (SELECT ID FROM TableB)

This would delete them

DELETE FROM TableA WHERE ID NOT IN (SELECT ID FROM TableB)

Extracting columns from text file with different delimiters in Linux

If the command should work with both tabs and spaces as the delimiter I would use awk:

awk '{print $100,$101,$102,$103,$104,$105}' myfile > outfile

As long as you just need to specify 5 fields it is imo ok to just type them, for longer ranges you can use a for loop:

awk '{for(i=100;i<=105;i++)print $i}' myfile > outfile

If you want to use cut, you need to use the -f option:

cut -f100-105 myfile > outfile

If the field delimiter is different from TAB you need to specify it using -d:

cut -d' ' -f100-105 myfile > outfile

Check the man page for more info on the cut command.

How to play .mp4 video in videoview in android?

Finally it works for me.

private VideoView videoView;

videoView = (VideoView) findViewById(R.id.videoView);

Uri video = Uri.parse("http://www.servername.com/projects/projectname/videos/1361439400.mp4");
videoView.setVideoURI(video);
videoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
  @Override       
  public void onPrepared(MediaPlayer mp) {
       mp.setLooping(true);
       videoView.start();
    }
});

Hope this would help others.

How do I finish the merge after resolving my merge conflicts?

How do I finish the merge after resolving my merge conflicts?

With Git 2.12 (Q1 2017), you will have the more natural command:

git merge --continue

See commit c7d227d (15 Dec 2016) by Jeff King (peff).
See commit 042e290, commit c261a87, commit 367ff69 (14 Dec 2016) by Chris Packham (cpackham).
(Merged by Junio C Hamano -- gitster -- in commit 05f6e1b, 27 Dec 2016)

See 2.12 release notes.

merge: add '--continue' option as a synonym for 'git commit'

Teach 'git merge' the --continue option which allows 'continuing' a merge by completing it.
The traditional way of completing a merge after resolving conflicts is to use 'git commit'.
Now with commands like 'git rebase' and 'git cherry-pick' having a '--continue' option adding such an option to 'git merge' presents a consistent UI.

Running Python in PowerShell?

As far as I have understood your question, you have listed two issues.

PROBLEM 1:

You are not able to execute the Python scripts by double clicking the Python file in Windows.

REASON:

The script runs too fast to be seen by the human eye.

SOLUTION:

Add input() in the bottom of your script and then try executing it with double click. Now the cmd will be open until you close it.

EXAMPLE:

print("Hello World")
input()

PROBLEM 2:

./ issue

SOLUTION:

Use Tab to autocomplete the filenames rather than manually typing the filename with ./ autocomplete automatically fills all this for you.

USAGE:

CD into the directory in which .py files are present and then assume the filename is test.py then type python te and then press Tab, it will be automatically converted to python ./test.py.

Counting the number of True Booleans in a Python List

list has a count method:

>>> [True,True,False].count(True)
2

This is actually more efficient than sum, as well as being more explicit about the intent, so there's no reason to use sum:

In [1]: import random

In [2]: x = [random.choice([True, False]) for i in range(100)]

In [3]: %timeit x.count(True)
970 ns ± 41.1 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

In [4]: %timeit sum(x)
1.72 µs ± 161 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)

How do I delete virtual interface in Linux?

You can use sudo ip link delete to remove the interface.

List supported SSL/TLS versions for a specific OpenSSL build

You can not check for version support via command line. Best option would be checking OpenSSL changelog.

Openssl versions till 1.0.0h supports SSLv2, SSLv3 and TLSv1.0. From Openssl 1.0.1 onward support for TLSv1.1 and TLSv1.2 is added.

How to convert int to float in python?

To convert an integer to a float in Python you can use the following:

float_version = float(int_version)

The reason you are getting 0 is that Python 2 returns an integer if the mathematical operation (here a division) is between two integers. So while the division of 144 by 314 is 0.45~~~, Python converts this to integer and returns just the 0 by eliminating all numbers after the decimal point.

Alternatively you can convert one of the numbers in any operation to a float since an operation between a float and an integer would return a float. In your case you could write float(144)/314 or 144/float(314). Another, less generic code, is to say 144.0/314. Here 144.0 is a float so it’s the same thing.

How to empty a char array?

I'd go with

members_in_use = 0;

Difference between single and double quotes in Bash

Single quotes won't interpolate anything, but double quotes will. For example: variables, backticks, certain \ escapes, etc.

Example:

$ echo "$(echo "upg")"
upg
$ echo '$(echo "upg")'
$(echo "upg")

The Bash manual has this to say:

3.1.2.2 Single Quotes

Enclosing characters in single quotes (') preserves the literal value of each character within the quotes. A single quote may not occur between single quotes, even when preceded by a backslash.

3.1.2.3 Double Quotes

Enclosing characters in double quotes (") preserves the literal value of all characters within the quotes, with the exception of $, `, \, and, when history expansion is enabled, !. The characters $ and ` retain their special meaning within double quotes (see Shell Expansions). The backslash retains its special meaning only when followed by one of the following characters: $, `, ", \, or newline. Within double quotes, backslashes that are followed by one of these characters are removed. Backslashes preceding characters without a special meaning are left unmodified. A double quote may be quoted within double quotes by preceding it with a backslash. If enabled, history expansion will be performed unless an ! appearing in double quotes is escaped using a backslash. The backslash preceding the ! is not removed.

The special parameters * and @ have special meaning when in double quotes (see Shell Parameter Expansion).

Split string in JavaScript and detect line break

In case you need to split a string from your JSON, the string has the \n special character replaced with \\n.

Split string by newline:

Result.split('\n');

Split string received in JSON, where special character \n was replaced with \\n during JSON.stringify(in javascript) or json.json_encode(in PHP). So, if you have your string in a AJAX response, it was processed for transportation. and if it is not decoded, it will sill have the \n replaced with \\n** and you need to use:

Result.split('\\n');

Note that the debugger tools from your browser might not show this aspect as you was expecting, but you can see that splitting by \\n resulted in 2 entries as I need in my case: enter image description here

How to make lists contain only distinct element in Python?

The characteristics of sets in Python are that the data items in a set are unordered and duplicates are not allowed. If you try to add a data item to a set that already contains the data item, Python simply ignores it.

>>> l = ['a', 'a', 'bb', 'b', 'c', 'c', '10', '10', '8','8', 10, 10, 6, 10, 11.2, 11.2, 11, 11]
>>> distinct_l = set(l)
>>> print(distinct_l)
set(['a', '10', 'c', 'b', 6, 'bb', 10, 11, 11.2, '8'])

Should I use window.navigate or document.location in JavaScript?

Late joining this conversation to shed light on a mildly interesting factoid for web-facing, analytics-aware websites. Passing the mic over to Michael Papworth:

https://github.com/michaelpapworth/jQuery.navigate

"When using website analytics, window.location is not sufficient due to the referer not being passed on the request. The plugin resolves this and allows for both aliased and parametrised URLs."

If one examines the code what it does is this:

   var methods = {
            'goTo': function (url) {
                // instead of using window.location to navigate away
                // we use an ephimeral link to click on and thus ensure
                // the referer (current url) is always passed on to the request
                $('<a></a>').attr("href", url)[0].click();
            },
            ...
   };

Neato!

Reading file contents on the client-side in javascript in various browsers

Happy coding!
If you get an error on Internet Explorer, Change the security settings to allow ActiveX

var CallBackFunction = function(content) {
  alert(content);
}
ReadFileAllBrowsers(document.getElementById("file_upload"), CallBackFunction);
//Tested in Mozilla Firefox browser, Chrome
function ReadFileAllBrowsers(FileElement, CallBackFunction) {
  try {
    var file = FileElement.files[0];
    var contents_ = "";

    if (file) {
      var reader = new FileReader();
      reader.readAsText(file, "UTF-8");
      reader.onload = function(evt) {
        CallBackFunction(evt.target.result);
      }
      reader.onerror = function(evt) {
        alert("Error reading file");
      }
    }
  } catch (Exception) {
    var fall_back = ieReadFile(FileElement.value);
    if (fall_back != false) {
      CallBackFunction(fall_back);
    }
  }
}
///Reading files with Internet Explorer
function ieReadFile(filename) {
  try {
    var fso = new ActiveXObject("Scripting.FileSystemObject");
    var fh = fso.OpenTextFile(filename, 1);
    var contents = fh.ReadAll();
    fh.Close();
    return contents;
  } catch (Exception) {
    alert(Exception);
    return false;
  }
}

ImportError: No module named enum

I ran into this same issue trying to install the dbf package in Python 2.7. The problem is that the enum package wasn't added to Python until version 3.4.

It has been backported to versions 3.3, 3.2, 3.1, 2.7, 2.6, 2.5, and 2.4, you just need the package from here: https://pypi.python.org/pypi/enum34#downloads

How to generate .NET 4.0 classes from xsd?

The command that worked in my case was:

xsd /c your.xsd 

Sqlite convert string to date

I am storing the date as 'DD-MON-YYYY format (10-Jun-2016) and below query works for me to search records between 2 dates.

select date, substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2),  case 
substr(date, 4,3) 
when 'Jan' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Jan' , '01')) 
when 'Feb' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Feb' , '02')) 
when 'Mar' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Mar' , '03')) 
when 'Apr' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Apr' , '04')) 
when 'May' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'May' , '05')) 
when 'Jun' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Jun' , '06')) 
when 'Jul' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Jul' , '07')) 
when 'Aug' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Aug' , '08')) 
when 'Sep' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Sep' , '09')) 
when 'Oct' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Oct' , '10')) 
when 'Nov' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Nov' , '11')) 
when 'Dec' then strftime('%s', replace(substr(date,8,11) || '-' || substr(date,4,4) || substr(date, 1,2), 'Dec' , '12')) 
else '0' end as srcDate from payment where srcDate >= strftime('%s', '2016-07-06') and srcDate <= strftime('%s', '2016-09-06');

How to center content in a bootstrap column?

Use text-center instead of center-block.

Or use center-block on the span element (I did the column wider so you can see the alignment better):

<div class="row">
   <div class="col-xs-10" style="background-color:#123;">
      <span class="center-block" style="width:100px; background-color:#ccc;">abc</span>
   </div>
</div>

How to convert XML to java.util.Map and vice versa

I used the approach with the custom converter:

public static class MapEntryConverter implements Converter {

    public boolean canConvert(Class clazz) {
        return AbstractMap.class.isAssignableFrom(clazz);
    }

    public void marshal(Object value, HierarchicalStreamWriter writer, MarshallingContext context) {

        AbstractMap map = (AbstractMap) value;
        for (Object obj : map.entrySet()) {
            Entry entry = (Entry) obj;
            writer.startNode(entry.getKey().toString());
            context.convertAnother(entry.getValue());
            writer.endNode();
        }
    }

    public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
        // dunno, read manual and do it yourself ;)
    }

}

But i changed the the serialization of the maps value to delegate to the MarshallingContext. This should improve the solution to work for composite map values and nested maps as well.

keycode 13 is for which key

That would be the Enter key.

Echo equivalent in PowerShell for script testing

There are several ways:

Write-Host: Write directly to the console, not included in function/cmdlet output. Allows foreground and background colour to be set.

Write-Debug: Write directly to the console, if $DebugPreference set to Continue or Stop.

Write-Verbose: Write directly to the console, if $VerbosePreference set to Continue or Stop.

The latter is intended for extra optional information, Write-Debug for debugging (so would seem to fit in this case).

Additional: In PSH2 (at least) scripts using cmdlet binding will automatically get the -Verbose and -Debug switch parameters, locally enabling Write-Verbose and Write-Debug (i.e. overriding the preference variables) as compiled cmdlets and providers do.

Configure nginx with multiple locations with different root folders on subdomain

server {

    index index.html index.htm;
    server_name test.example.com;

    location / {
        root /web/test.example.com/www;
    }

    location /static {
        root /web/test.example.com;
    }
}

http://nginx.org/r/root

Regex for allowing alphanumeric,-,_ and space

Character sets will help out a ton here. You want to create a matching set for the characters that you want to validate:

  • You can match alphanumeric with a \w, which is the same as [A-Za-z0-9_] in JavaScript (other languages can differ).
  • That leaves - and spaces, which can be combined into a matching set such as [\w\- ]. However, you may want to consider using \s instead of just the space character (\s also matches tabs, and other forms of whitespace)
    • Note that I'm escaping - as \- so that the regex engine doesn't confuse it with a character range like A-Z
  • Last up, you probably want to ensure that the entire string matches by anchoring the start and end via ^ and $

The full regex you're probably looking for is:

/^[\w\-\s]+$/

(Note that the + indicates that there must be at least one character for it to match; use a * instead, if a zero-length string is also ok)

Finally, http://www.regular-expressions.info/ is an awesome reference


Bonus Points: This regex does not match non-ASCII alphas. Unfortunately, the regex engine in most browsers does not support named character sets, but there are some libraries to help with that.

For languages/platforms that do support named character sets, you can use /^[\p{Letter}\d\_\-\s]+$/

Detect whether a Python string is a number or a letter

Check if string is positive digit (integer) and alphabet

You may use str.isdigit() and str.isalpha() to check whether given string is positive integer and alphabet respectively.

Sample Results:

# For alphabet
>>> 'A'.isdigit()
False
>>> 'A'.isalpha()
True

# For digit
>>> '1'.isdigit()
True
>>> '1'.isalpha()
False

Check for strings as positive/negative - integer/float

str.isdigit() returns False if the string is a negative number or a float number. For example:

# returns `False` for float
>>> '123.3'.isdigit()
False
# returns `False` for negative number
>>> '-123'.isdigit()
False

If you want to also check for the negative integers and float, then you may write a custom function to check for it as:

def is_number(n):
    try:
        float(n)   # Type-casting the string to `float`.
                   # If string is not a valid `float`, 
                   # it'll raise `ValueError` exception
    except ValueError:
        return False
    return True

Sample Run:

>>> is_number('123')    # positive integer number
True

>>> is_number('123.4')  # positive float number
True
 
>>> is_number('-123')   # negative integer number
True

>>> is_number('-123.4') # negative `float` number
True

>>> is_number('abc')    # `False` for "some random" string
False

Discard "NaN" (not a number) strings while checking for number

The above functions will return True for the "NAN" (Not a number) string because for Python it is valid float representing it is not a number. For example:

>>> is_number('NaN')
True

In order to check whether the number is "NaN", you may use math.isnan() as:

>>> import math
>>> nan_num = float('nan')

>>> math.isnan(nan_num)
True

Or if you don't want to import additional library to check this, then you may simply check it via comparing it with itself using ==. Python returns False when nan float is compared with itself. For example:

# `nan_num` variable is taken from above example
>>> nan_num == nan_num
False

Hence, above function is_number can be updated to return False for "NaN" as:

def is_number(n):
    is_number = True
    try:
        num = float(n)
        # check for "nan" floats
        is_number = num == num   # or use `math.isnan(num)`
    except ValueError:
        is_number = False
    return is_number

Sample Run:

>>> is_number('Nan')   # not a number "Nan" string
False

>>> is_number('nan')   # not a number string "nan" with all lower cased
False

>>> is_number('123')   # positive integer
True

>>> is_number('-123')  # negative integer
True

>>> is_number('-1.12') # negative `float`
True

>>> is_number('abc')   # "some random" string
False

Allow Complex Number like "1+2j" to be treated as valid number

The above function will still return you False for the complex numbers. If you want your is_number function to treat complex numbers as valid number, then you need to type cast your passed string to complex() instead of float(). Then your is_number function will look like:

def is_number(n):
    is_number = True
    try:
        #      v type-casting the number here as `complex`, instead of `float`
        num = complex(n)
        is_number = num == num
    except ValueError:
        is_number = False
    return is_number

Sample Run:

>>> is_number('1+2j')    # Valid 
True                     #      : complex number 

>>> is_number('1+ 2j')   # Invalid 
False                    #      : string with space in complex number represetantion
                         #        is treated as invalid complex number

>>> is_number('123')     # Valid
True                     #      : positive integer

>>> is_number('-123')    # Valid 
True                     #      : negative integer

>>> is_number('abc')     # Invalid 
False                    #      : some random string, not a valid number

>>> is_number('nan')     # Invalid
False                    #      : not a number "nan" string

PS: Each operation for each check depending on the type of number comes with additional overhead. Choose the version of is_number function which fits your requirement.

What is the size limit of a post request?

As David pointed out, I would go with KB in most cases.

php_value post_max_size 2K

Note: my form is simple, just a few text boxes, not long text.

(PHP shorthand for KB is K, as outlined here.)

Java split string to array

This is expected. Refer to Javadocs for split.

Splits this string around matches of the given regular expression.

This method works as if by invoking the two-argument split(java.lang.String,int) method with the given expression and a limit argument of zero. Trailing empty strings are therefore not included in the resulting array.

How do I find the current machine's full hostname in C (hostname and domain information)?

The easy way, try uname()

If that does not work, use gethostname() then gethostbyname() and finally gethostbyaddr()

The h_name of hostent{} should be your FQDN

How to print table using Javascript?

You can also use a jQuery plugin to do that

jQuery PrintPage plugin

Demo

Deep-Learning Nan loss reasons

If you'd like to gather more information on the error and if the error occurs in the first few iterations, I suggest you run the experiment in CPU-only mode (no GPUs). The error message will be much more specific.

Source: https://github.com/tensorflow/tensor2tensor/issues/574

Cast object to T

You could require the type to be a reference type :

 private static T ReadData<T>(XmlReader reader, string value) where T : class
 {
     reader.MoveToAttribute(value);
     object readData = reader.ReadContentAsObject();
     return (T)readData;
 }

And then do another that uses value types and TryParse...

 private static T ReadDataV<T>(XmlReader reader, string value) where T : struct
 {
     reader.MoveToAttribute(value);
     object readData = reader.ReadContentAsObject();
     int outInt;
     if(int.TryParse(readData, out outInt))
        return outInt
     //...
 }

Convert to absolute value in Objective-C

You can use this function to get the absolute value:

+(NSNumber *)absoluteValue:(NSNumber *)input {
  return [NSNumber numberWithDouble:fabs([input doubleValue])];
}

Open Excel file for reading with VBA without display

Using ADO (AnonJr already explained) and utilizing SQL is possibly the best option for fetching data from a closed workbook without opening that in conventional way. Please watch this VIDEO.

OTHERWISE, possibly GetObject(<filename with path>) is the most CONCISE way. Worksheets remain invisible, however will appear in project explorer window in VBE just like any other workbook opened in conventional ways.

Dim wb As Workbook

Set wb = GetObject("C:\MyData.xlsx")  'Worksheets will remain invisible, no new window appears in the screen
' your codes here
wb.Close SaveChanges:=False

If you want to read a particular sheet, need not even define a Workbook variable

Dim sh As Worksheet
Set sh = GetObject("C:\MyData.xlsx").Worksheets("MySheet")
' your codes here
sh.Parent.Close SaveChanges:=False 'Closes the associated workbook

Open Source HTML to PDF Renderer with Full CSS Support

I've always used it on the command line and not as a library, but HTMLDOC gives me excellent results, and it handles at least some CSS (I couldn't easily see how much).

Here's a sample command line

htmldoc --webpage -t pdf --size letter --fontsize 10pt index.html > index.pdf

Recyclerview inside ScrollView not scrolling smoothly

Using Nested Scroll View instead of Scroll View solved my problem

<LinearLayout> <!--Main Layout -->
   <android.support.v4.widget.NestedScrollView>
     <LinearLayout > <!--Nested Scoll View enclosing Layout -->`

       <View > <!-- upper content --> 
       <RecyclerView >


     </LinearLayout > 
   </android.support.v4.widget.NestedScrollView>
</LinearLayout>

Generate 'n' unique random numbers within a range

If you just need sampling without replacement:

>>> import random
>>> random.sample(range(1, 100), 3)
[77, 52, 45]

random.sample takes a population and a sample size k and returns k random members of the population.

If you have to control for the case where k is larger than len(population), you need to be prepared to catch a ValueError:

>>> try:
...   random.sample(range(1, 2), 3)
... except ValueError:
...   print('Sample size exceeded population size.')
... 
Sample size exceeded population size

Eliminating NAs from a ggplot

You can use the function subset inside ggplot2. Try this

library(ggplot2)

data("iris")
iris$Sepal.Length[5:10] <- NA # create some NAs for this example

ggplot(data=subset(iris, !is.na(Sepal.Length)), aes(x=Sepal.Length)) + 
geom_bar(stat="bin")

How do I concatenate two strings in C?

David Heffernan explained the issue in his answer, and I wrote the improved code. See below.

A generic function

We can write a useful variadic function to concatenate any number of strings:

#include <stdlib.h>       // calloc
#include <stdarg.h>       // va_*
#include <string.h>       // strlen, strcpy

char* concat(int count, ...)
{
    va_list ap;
    int i;

    // Find required length to store merged string
    int len = 1; // room for NULL
    va_start(ap, count);
    for(i=0 ; i<count ; i++)
        len += strlen(va_arg(ap, char*));
    va_end(ap);

    // Allocate memory to concat strings
    char *merged = calloc(sizeof(char),len);
    int null_pos = 0;

    // Actually concatenate strings
    va_start(ap, count);
    for(i=0 ; i<count ; i++)
    {
        char *s = va_arg(ap, char*);
        strcpy(merged+null_pos, s);
        null_pos += strlen(s);
    }
    va_end(ap);

    return merged;
}

Usage

#include <stdio.h>        // printf

void println(char *line)
{
    printf("%s\n", line);
}

int main(int argc, char* argv[])
{
    char *str;

    str = concat(0);             println(str); free(str);
    str = concat(1,"a");         println(str); free(str);
    str = concat(2,"a","b");     println(str); free(str);
    str = concat(3,"a","b","c"); println(str); free(str);

    return 0;
}

Output:

  // Empty line
a
ab
abc

Clean-up

Note that you should free up the allocated memory when it becomes unneeded to avoid memory leaks:

char *str = concat(2,"a","b");
println(str);
free(str);

Java - Including variables within strings?

Since Java 15, you can use a non-static string method called String::formatted(Object... args)

Example:

String foo = "foo";
String bar = "bar";

String str = "First %s, then %s".formatted(foo, bar);     

Output:

"First foo, then bar"

How to set background image in Java?

The answer will vary slightly depending on whether the application or applet is using AWT or Swing.

(Basically, classes that start with J such as JApplet and JFrame are Swing, and Applet and Frame are AWT.)

In either case, the basic steps would be:

  1. Draw or load an image into a Image object.
  2. Draw the background image in the painting event of the Component you want to draw the background in.

Step 1. Loading the image can be either by using the Toolkit class or by the ImageIO class.

The Toolkit.createImage method can be used to load an Image from a location specified in a String:

Image img = Toolkit.getDefaultToolkit().createImage("background.jpg");

Similarly, ImageIO can be used:

Image img = ImageIO.read(new File("background.jpg");

Step 2. The painting method for the Component that should get the background will need to be overridden and paint the Image onto the component.

For AWT, the method to override is the paint method, and use the drawImage method of the Graphics object that is handed into the paint method:

public void paint(Graphics g)
{
    // Draw the previously loaded image to Component.
    g.drawImage(img, 0, 0, null);

    // Draw sprites, and other things.
    // ....
}

For Swing, the method to override is the paintComponent method of the JComponent, and draw the Image as with what was done in AWT.

public void paintComponent(Graphics g)
{
    // Draw the previously loaded image to Component.
    g.drawImage(img, 0, 0, null);

    // Draw sprites, and other things.
    // ....
}

Simple Component Example

Here's a Panel which loads an image file when instantiated, and draws that image on itself:

class BackgroundPanel extends Panel
{
    // The Image to store the background image in.
    Image img;
    public BackgroundPanel()
    {
        // Loads the background image and stores in img object.
        img = Toolkit.getDefaultToolkit().createImage("background.jpg");
    }

    public void paint(Graphics g)
    {
        // Draws the img to the BackgroundPanel.
        g.drawImage(img, 0, 0, null);
    }
}

For more information on painting:

Deep copy an array in Angular 2 + TypeScript

A clean way of deep copying objects having nested objects inside is by using lodash's cloneDeep method.

For Angular, you can do it like this:

Install lodash with yarn add lodash or npm install lodash.

In your component, import cloneDeep and use it:

import * as cloneDeep from 'lodash/cloneDeep';
...
clonedObject = cloneDeep(originalObject);

It's only 18kb added to your build, well worth for the benefits.

I've also written an article here, if you need more insight on why using lodash's cloneDeep.

Where are Docker images stored on the host machine?

If anyone need it for scripting purposes, here is a one-line solution.

In POSIX shell, with PCRE enabled grep, try:

DOCKER_ROOT_DIR="$(docker info 2>&1 | grep -oP '(?<=^Docker Root Dir: ).*')"

In PowerShell:

$DOCKER_ROOT_DIR="$(docker info 2>&1 | foreach {if($_ -match "Docker Root Dir"){$_.TrimStart("Docker Root Dir: ")}})"

Note, when on Windows 10 (as of 10.0.18999.1), in default configurations, it returns:

  • C:\ProgramData\Docker in "Windows containers" mode
  • /var/lib/docker, in "Linux containers" mode

Error Code 1292 - Truncated incorrect DOUBLE value - Mysql

I've seen a couple cases where this error occurs:

1. using the not equals operator != in a where clause with a list of multiple or values

such as:

where columnName !=('A'||'B')

This can be resolved by using

where columnName not in ('A','B')

2. missing a comparison operator in an if() function:

select if(col1,col1,col2);

in order to select the value in col1 if it exists and otherwise show the value in col2...this throws the error; it can be resolved by using:

select if(col1!='',col1,col2);

SimpleXML - I/O warning : failed to load external entity

this also works:

$url = "http://www.some-url";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$xmlresponse = curl_exec($ch);
$xml=simplexml_load_string($xmlresponse);

then I just run a forloop to grab the stuff from the nodes.

like this:`

for($i = 0; $i < 20; $i++) {
$title = $xml->channel->item[$i]->title;
$link = $xml->channel->item[$i]->link;
$desc = $xml->channel->item[$i]->description;
$html .="<div><h3>$title</h3>$link<br />$desc</div><hr>";
}
echo $html;

***note that your node names will differ, obviously..and your HTML might be structured differently...also your loop might be set to higher or lower amount of results.

Best practice for partial updates in a RESTful service

Check out http://www.odata.org/

It defines the MERGE method, so in your case it would be something like this:

MERGE /customer/123

<customer>
   <status>DISABLED</status>
</customer>

Only the status property is updated and the other values are preserved.

LINQ select in C# dictionary

var res = exitDictionary
            .Select(p => p.Value).Cast<Dictionary<string, object>>()
            .SelectMany(d => d)
            .Where(p => p.Key == "fieldname1")
            .Select(p => p.Value).Cast<List<Dictionary<string,string>>>()
            .SelectMany(l => l)
            .SelectMany(d=> d)
            .Where(p => p.Key == "valueTitle")
            .Select(p => p.Value)
            .ToList();

This also works, and easy to understand.

Using msbuild to execute a File System Publish Profile

Found the answer here: http://www.digitallycreated.net/Blog/59/locally-publishing-a-vs2010-asp.net-web-application-using-msbuild

Visual Studio 2010 has great new Web Application Project publishing features that allow you to easy publish your web app project with a click of a button. Behind the scenes the Web.config transformation and package building is done by a massive MSBuild script that’s imported into your project file (found at: C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v10.0\Web\Microsoft.Web.Publishing.targets). Unfortunately, the script is hugely complicated, messy and undocumented (other then some oft-badly spelled and mostly useless comments in the file). A big flowchart of that file and some documentation about how to hook into it would be nice, but seems to be sadly lacking (or at least I can’t find it).

Unfortunately, this means performing publishing via the command line is much more opaque than it needs to be. I was surprised by the lack of documentation in this area, because these days many shops use a continuous integration server and some even do automated deployment (which the VS2010 publishing features could help a lot with), so I would have thought that enabling this (easily!) would be have been a fairly main requirement for the feature.

Anyway, after digging through the Microsoft.Web.Publishing.targets file for hours and banging my head against the trial and error wall, I’ve managed to figure out how Visual Studio seems to perform its magic one click “Publish to File System” and “Build Deployment Package” features. I’ll be getting into a bit of MSBuild scripting, so if you’re not familiar with MSBuild I suggest you check out this crash course MSDN page.

Publish to File System

The VS2010 Publish To File System Dialog Publish to File System took me a while to nut out because I expected some sensible use of MSBuild to be occurring. Instead, VS2010 does something quite weird: it calls on MSBuild to perform a sort of half-deploy that prepares the web app’s files in your project’s obj folder, then it seems to do a manual copy of those files (ie. outside of MSBuild) into your target publish folder. This is really whack behaviour because MSBuild is designed to copy files around (and other build-related things), so it’d make sense if the whole process was just one MSBuild target that VS2010 called on, not a target then a manual copy.

This means that doing this via MSBuild on the command-line isn’t as simple as invoking your project file with a particular target and setting some properties. You’ll need to do what VS2010 ought to have done: create a target yourself that performs the half-deploy then copies the results to the target folder. To edit your project file, right click on the project in VS2010 and click Unload Project, then right click again and click Edit. Scroll down until you find the Import element that imports the web application targets (Microsoft.WebApplication.targets; this file itself imports the Microsoft.Web.Publishing.targets file mentioned earlier). Underneath this line we’ll add our new target, called PublishToFileSystem:

<Target Name="PublishToFileSystem"
        DependsOnTargets="PipelinePreDeployCopyAllFilesToOneFolder">
    <Error Condition="'$(PublishDestination)'==''"
           Text="The PublishDestination property must be set to the intended publishing destination." />
    <MakeDir Condition="!Exists($(PublishDestination))"
             Directories="$(PublishDestination)" />

    <ItemGroup>
        <PublishFiles Include="$(_PackageTempDir)\**\*.*" />
    </ItemGroup>

    <Copy SourceFiles="@(PublishFiles)"
          DestinationFiles="@(PublishFiles->'$(PublishDestination)\%(RecursiveDir)%(Filename)%(Extension)')"
          SkipUnchangedFiles="True" />
</Target>

This target depends on the PipelinePreDeployCopyAllFilesToOneFolder target, which is what VS2010 calls before it does its manual copy. Some digging around in Microsoft.Web.Publishing.targets shows that calling this target causes the project files to be placed into the directory specified by the property _PackageTempDir.

The first task we call in our target is the Error task, upon which we’ve placed a condition that ensures that the task only happens if the PublishDestination property hasn’t been set. This will catch you and error out the build in case you’ve forgotten to specify the PublishDestination property. We then call the MakeDir task to create that PublishDestination directory if it doesn’t already exist.

We then define an Item called PublishFiles that represents all the files found under the _PackageTempDir folder. The Copy task is then called which copies all those files to the Publish Destination folder. The DestinationFiles attribute on the Copy element is a bit complex; it performs a transform of the items and converts their paths to new paths rooted at the PublishDestination folder (check out Well-Known Item Metadata to see what those %()s mean).

To call this target from the command-line we can now simply perform this command (obviously changing the project file name and properties to suit you):

msbuild Website.csproj "/p:Platform=AnyCPU;Configuration=Release;PublishDestination=F:\Temp\Publish" /t:PublishToFileSystem

Swift - How to hide back button in navigation item?

In case you're using a UITabBarController:

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)
    self.tabBarController?.navigationItem.hidesBackButton = true
}

How to get a Color from hexadecimal Color String

Try Color class method:

public static int parseColor (String colorString)

From Android documentation:

Supported formats are: #RRGGBB #AARRGGBB 'red', 'blue', 'green', 'black', 'white', 'gray', 'cyan', 'magenta', 'yellow', 'lightgray', 'darkgray'

AndroidX: String.toColorInt()

What does it mean to "call" a function in Python?

To "call" means to make a reference in your code to a function that is written elsewhere. This function "call" can be made to the standard Python library (stuff that comes installed with Python), third-party libraries (stuff other people wrote that you want to use), or your own code (stuff you wrote). For example:

#!/usr/env python

import os

def foo():
    return "hello world"

print os.getlogin()
print foo()

I created a function called "foo" and called it later on with that print statement. I imported the standard "os" Python library then I called the "getlogin" function within that library.

MySQL Workbench Edit Table Data is read only

I'm assuming the table has a primary key. First try to run a unlock tables command to see if that fixes it.

If all else fails you can alter the table to create a new primary key column with auto-increment and that should hopefully fix it. Once you're done you should be able to remove the column without any issues.

As always you want to make a backup before altering tables around. :)

Note: MySQL workbench cannot work without a primary key if that's your issue. However if you have a many to many table you can set both columns as primary keys which will let you edit the data.

How to write a simple Html.DropDownListFor()?

@using (Html.BeginForm()) {
    <p>Do you like pizza?
        @Html.DropDownListFor(x => x.likesPizza, new[] {
            new SelectListItem() {Text = "Yes", Value = bool.TrueString},
            new SelectListItem() {Text = "No", Value = bool.FalseString}
        }, "Choose an option") 
    </p>
    <input type = "submit" value = "Submit my answer" />
} 

I think this answer is similar to Berat's, in that you put all the code for your DropDownList directly in the view. But I think this is an efficient way of creating a y/n (boolean) drop down list, so I wanted to share it.

Some notes for beginners:

  • Don't worry about what 'x' is called - it is created here, for the first time, and doesn't link to anything else anywhere else in the MVC app, so you can call it what you want - 'x', 'model', 'm' etc.
  • The placeholder that users will see in the dropdown list is "Choose an option", so you can change this if you want.
  • There's a bit of text preceding the drop down which says "Do you like pizza?"
  • This should be complete text for a form, including a submit button, I think

Hope this helps someone,

How do I apply CSS3 transition to all properties except background-position?

Try:

-webkit-transition: all .2s linear, background-position 0;

This worked for me on something similar..

Linux command for extracting war file?

Extracting a specific folder (directory) within war file:

# unzip <war file> '<folder to extract/*>' -d <destination path> 
unzip app##123.war 'some-dir/*' -d extracted/

You get ./extracted/some-dir/ as a result.

Angular2 change detection: ngOnChanges not firing for nested object

I stumbled upon the same need. And I read a lot on this so, here is my copper on the subject.

If you want your change detection on push, then you would have it when you change a value of an object inside right ? And you also would have it if somehow, you remove objects.

As already said, use of changeDetectionStrategy.onPush

Say you have this component you made, with changeDetectionStrategy.onPush:

<component [collection]="myCollection"></component>

Then you'd push an item and trigger the change detection :

myCollection.push(anItem);
refresh();

or you'd remove an item and trigger the change detection :

myCollection.splice(0,1);
refresh();

or you'd change an attrbibute value for an item and trigger the change detection :

myCollection[5].attribute = 'new value';
refresh();

Content of refresh :

refresh() : void {
    this.myCollection = this.myCollection.slice();
}

The slice method returns the exact same Array, and the [ = ] sign make a new reference to it, triggering the change detection every time you need it. Easy and readable :)

Regards,

Matching special characters and letters in regex

Well, why not just add them to your existing character class?

var pattern = /[a-zA-Z0-9&._-]/

If you need to check whether a string consists of nothing but those characters you have to anchor the expression as well:

var pattern = /^[a-zA-Z0-9&._-]+$/

The added ^ and $ match the beginning and end of the string respectively.

Testing for letters, numbers or underscore can be done with \w which shortens your expression:

var pattern = /^[\w&.-]+$/

As mentioned in the comment from Nathan, if you're not using the results from .match() (it returns an array with what has been matched), it's better to use RegExp.test() which returns a simple boolean:

if (pattern.test(qry)) {
    // qry is non-empty and only contains letters, numbers or special characters.
}

Update 2

In case I have misread the question, the below will check if all three separate conditions are met.

if (/[a-zA-Z]/.test(qry) && /[0-9]/.test(qry) && /[&._-]/.test(qry)) {
   // qry contains at least one letter, one number and one special character
}

How to clear memory to prevent "out of memory error" in excel vba?

If you operate on a large dataset, it is very possible that arrays will be used. For me creating a few arrays from 500 000 rows and 30 columns worksheet caused this error. I solved it simply by using the line below to get rid of array which is no longer necessary to me, before creating another one:

Erase vArray

Also if only 2 columns out of 30 are used, it is a good idea to create two 1-column arrays instead of one with 30 columns. It doesn't affect speed, but there will be a difference in memory usage.

How do I get the directory that a program is running from?

If you want a standard way without libraries: No. The whole concept of a directory is not included in the standard.

If you agree that some (portable) dependency on a near-standard lib is okay: Use Boost's filesystem library and ask for the initial_path().

IMHO that's as close as you can get, with good karma (Boost is a well-established high quality set of libraries)

How to access share folder in virtualbox. Host Win7, Guest Fedora 16?

There's a simpler way I found when running Linux Mint.

  1. Ensure you install the Guest Additions from the command line and that you have the folder(s) shared with "automount" and "make permanent" settings selected within "Shared Folders" tab of the Machine Settings
  2. Launch the User management application from Application/Settings/System Setting/ menu selection (requires sudo) from within the Mint menu
  3. In the "Privileges and Groups" tab, check the box next to the "vboxsf" group, and then apply and ok your way back out.

Any user within the vboxsf group has full access to any shared folders on each boot with no manual mounting or unmounting

I usually do the following in addition to the above just to have quick access

  1. Open the Dolphin file manager and navigate to /media/
  2. Right-Click on the shared folder and click "Add to Places"

What is the full path to the Packages folder for Sublime text 2 on Mac OS Lion

A useful shortcut from inside Sublime Text:

cmd-shift-P --> Browse Packages Now open user folder.

adb shell command to make Android package uninstall dialog appear

You can do it from adb using this command:

adb shell am start -a android.intent.action.DELETE -d package:<your app package>

How do I use CREATE OR REPLACE?

-- To Create or Replace a Table we must first silently Drop a Table that may not exist
DECLARE
  table_not_exist EXCEPTION;
  PRAGMA EXCEPTION_INIT (table_not_exist , -00942);
BEGIN
   EXECUTE IMMEDIATE('DROP TABLE <SCHEMA>.<TABLE NAME> CASCADE CONSTRAINTS');
   EXCEPTION WHEN table_not_exist THEN NULL;
END;
/

Best way to encode text data for XML in Java?

Note: Your question is about escaping, not encoding. Escaping is using <, etc. to allow the parser to distinguish between "this is an XML command" and "this is some text". Encoding is the stuff you specify in the XML header (UTF-8, ISO-8859-1, etc).

First of all, like everyone else said, use an XML library. XML looks simple but the encoding+escaping stuff is dark voodoo (which you'll notice as soon as you encounter umlauts and Japanese and other weird stuff like "full width digits" (&#FF11; is 1)). Keeping XML human readable is a Sisyphus' task.

I suggest never to try to be clever about text encoding and escaping in XML. But don't let that stop you from trying; just remember when it bites you (and it will).

That said, if you use only UTF-8, to make things more readable you can consider this strategy:

  • If the text does contain '<', '>' or '&', wrap it in <![CDATA[ ... ]]>
  • If the text doesn't contain these three characters, don't warp it.

I'm using this in an SQL editor and it allows the developers to cut&paste SQL from a third party SQL tool into the XML without worrying about escaping. This works because the SQL can't contain umlauts in our case, so I'm safe.

Tools to search for strings inside files without indexing

Original Answer

Windows Grep does this really well.

Edit: Windows Grep is no longer being maintained or made available by the developer. An alternate download link is here: Windows Grep - alternate

Current Answer

Visual Studio Code has excellent search and replace capabilities across files. It is extremely fast, supports regex and live preview before replacement.

enter image description here

How can I change image tintColor in iOS and WatchKit

This is my UIImage extension and you can directly use changeTintColor function for an image.

extension UIImage {

    func changeTintColor(color: UIColor) -> UIImage {
        var newImage = self.withRenderingMode(.alwaysTemplate)
        UIGraphicsBeginImageContextWithOptions(self.size, false, newImage.scale)
        color.set()
        newImage.draw(in: CGRect(x: 0.0, y: 0.0, width: self.size.width, height: self.size.height))
        newImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return newImage
    }

    func changeColor(color: UIColor) -> UIImage {
        let backgroundSize = self.size
        UIGraphicsBeginImageContext(backgroundSize)
        guard let context = UIGraphicsGetCurrentContext() else {
            return self
        }
        var backgroundRect = CGRect()
        backgroundRect.size = backgroundSize
        backgroundRect.origin.x = 0
        backgroundRect.origin.y = 0

        var red: CGFloat = 0
        var green: CGFloat = 0
        var blue: CGFloat = 0
        var alpha: CGFloat = 0
        color.getRed(&red, green: &green, blue: &blue, alpha: &alpha)
        context.setFillColor(red: red, green: green, blue: blue, alpha: alpha)
        context.translateBy(x: 0, y: backgroundSize.height)
        context.scaleBy(x: 1.0, y: -1.0)
        context.clip(to: CGRect(x: 0.0, y: 0.0, width: self.size.width, height: self.size.height),
                 mask: self.cgImage!)
        context.fill(backgroundRect)

        var imageRect = CGRect()
        imageRect.size = self.size
        imageRect.origin.x = (backgroundSize.width - self.size.width) / 2
        imageRect.origin.y = (backgroundSize.height - self.size.height) / 2

        context.setBlendMode(.multiply)
        context.draw(self.cgImage!, in: imageRect)

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return newImage!
    }

}

Example usage like this

let image = UIImage(named: "sample_image")
imageView.image = image.changeTintColor(color: UIColor.red)

And you can use change changeColor function to change the image color

Select rows having 2 columns equal value

SELECT t1.* FROM table t1 JOIN table t2 ON t1.Id=t2.Id WHERE t1.C4=t2.C4;

Giving Accurate Result for me.

Undefined Symbols for architecture x86_64: Compiling problems

There's no mystery here, the linker is telling you that you haven't defined the missing symbols, and you haven't.

Similarity::Similarity() or Similarity::~Similarity() are just missing and you have defined the others incorrectly,

void Similarity::readData(Scanner& inStream){
}

not

void readData(Scanner& inStream){
}

etc. etc.

The second one is a function called readData, only the first is the readData method of the Similarity class.

To be clear about this, in Similarity.h

void readData(Scanner& inStream);

but in Similarity.cpp

void Similarity::readData(Scanner& inStream){
}

Why use a ReentrantLock if one can use synchronized(this)?

A ReentrantLock is unstructured, unlike synchronized constructs -- i.e. you don't need to use a block structure for locking and can even hold a lock across methods. An example:

private ReentrantLock lock;

public void foo() {
  ...
  lock.lock();
  ...
}

public void bar() {
  ...
  lock.unlock();
  ...
}

Such flow is impossible to represent via a single monitor in a synchronized construct.


Aside from that, ReentrantLock supports lock polling and interruptible lock waits that support time-out. ReentrantLock also has support for configurable fairness policy, allowing more flexible thread scheduling.

The constructor for this class accepts an optional fairness parameter. When set true, under contention, locks favor granting access to the longest-waiting thread. Otherwise this lock does not guarantee any particular access order. Programs using fair locks accessed by many threads may display lower overall throughput (i.e., are slower; often much slower) than those using the default setting, but have smaller variances in times to obtain locks and guarantee lack of starvation. Note however, that fairness of locks does not guarantee fairness of thread scheduling. Thus, one of many threads using a fair lock may obtain it multiple times in succession while other active threads are not progressing and not currently holding the lock. Also note that the untimed tryLock method does not honor the fairness setting. It will succeed if the lock is available even if other threads are waiting.


ReentrantLock may also be more scalable, performing much better under higher contention. You can read more about this here.

This claim has been contested, however; see the following comment:

In the reentrant lock test, a new lock is created each time, thus there is no exclusive locking and the resulting data is invalid. Also, the IBM link offers no source code for the underlying benchmark so its impossible to characterize whether the test was even conducted correctly.


When should you use ReentrantLocks? According to that developerWorks article...

The answer is pretty simple -- use it when you actually need something it provides that synchronized doesn't, like timed lock waits, interruptible lock waits, non-block-structured locks, multiple condition variables, or lock polling. ReentrantLock also has scalability benefits, and you should use it if you actually have a situation that exhibits high contention, but remember that the vast majority of synchronized blocks hardly ever exhibit any contention, let alone high contention. I would advise developing with synchronization until synchronization has proven to be inadequate, rather than simply assuming "the performance will be better" if you use ReentrantLock. Remember, these are advanced tools for advanced users. (And truly advanced users tend to prefer the simplest tools they can find until they're convinced the simple tools are inadequate.) As always, make it right first, and then worry about whether or not you have to make it faster.


One final aspect that's gonna become more relevant in the near future has to do with Java 15 and Project Loom. In the (new) world of virtual threads, the underlying scheduler would be able to work much better with ReentrantLock than it's able to do with synchronized, that's true at least in the initial Java 15 release but may be optimized later.

In the current Loom implementation, a virtual thread can be pinned in two situations: when there is a native frame on the stack — when Java code calls into native code (JNI) that then calls back into Java — and when inside a synchronized block or method. In those cases, blocking the virtual thread will block the physical thread that carries it. Once the native call completes or the monitor released (the synchronized block/method is exited) the thread is unpinned.

If you have a common I/O operation guarded by a synchronized, replace the monitor with a ReentrantLock to let your application benefit fully from Loom’s scalability boost even before we fix pinning by monitors (or, better yet, use the higher-performance StampedLock if you can).

VBA Excel sort range by specific column

If the starting cell of the range and of the key is static, the solution can be very simple:

Range("A3").Select
Range(Selection, Selection.End(xlToRight)).Select
Range(Selection, Selection.End(xlDown)).Select
Selection.Sort key1:=Range("B3", Range("B3").End(xlDown)), _
order1:=xlAscending, Header:=xlNo

Remove CSS class from element with JavaScript (no jQuery)

It's very simple, I think.

document.getElementById("whatever").classList.remove("className");

How to catch exception output from Python subprocess.check_output()?

This did the trick for me. It captures all the stdout output from the subprocess(For python 3.8):

from subprocess import check_output, STDOUT
cmd = "Your Command goes here"
try:
    cmd_stdout = check_output(cmd, stderr=STDOUT, shell=True).decode()
except Exception as e:
    print(e.output.decode()) # print out the stdout messages up to the exception
    print(e) # To print out the exception message

Getting realtime output using subprocess

I ran into the same problem awhile back. My solution was to ditch iterating for the read method, which will return immediately even if your subprocess isn't finished executing, etc.

Get row-index values of Pandas DataFrame as list?

If you're only getting these to manually pass into df.set_index(), that's unnecessary. Just directly do df.set_index['your_col_name', drop=False], already.

It's very rare in pandas that you need to get an index as a Python list (unless you're doing something pretty funky, or else passing them back to NumPy), so if you're doing this a lot, it's a code smell that you're doing something wrong.

Numpy, multiply array with scalar

You can multiply numpy arrays by scalars and it just works.

>>> import numpy as np
>>> np.array([1, 2, 3]) * 2
array([2, 4, 6])
>>> np.array([[1, 2, 3], [4, 5, 6]]) * 2
array([[ 2,  4,  6],
       [ 8, 10, 12]])

This is also a very fast and efficient operation. With your example:

>>> a_1 = np.array([1.0, 2.0, 3.0])
>>> a_2 = np.array([[1., 2.], [3., 4.]])
>>> b = 2.0
>>> a_1 * b
array([2., 4., 6.])
>>> a_2 * b
array([[2., 4.],
       [6., 8.]])

How can I get the root domain URI in ASP.NET?

--Adding the port can help when running IIS Express

Request.Url.Scheme + "://" + Request.Url.Host + ":" + Request.Url.Port

How to loop over directories in Linux?

If you want to execute multiple commands in a for loop, you can save the result of find with mapfile (bash >= 4) as an variable and go through the array with ${dirlist[@]}. It also works with directories containing spaces.

The find command is based on the answer by Boldewyn. Further information about the find command can be found there.

IFS=""
mapfile -t dirlist < <( find . -maxdepth 1 -mindepth 1 -type d -printf '%f\n' )
for dir in ${dirlist[@]}; do
    echo ">${dir}<"
    # more commands can go here ...
done

dlib installation on Windows 10

As you can see many answers above, But i would like to post a quick solution which works for sure in Anaconda3. I haven't chosen Visual Studio as it consumes lot of memory.

Please follow the below steps.

Step 1:
Install windows cmake.msi and configure environment variable
Step 2:
Create a conda environment, and install cmake using the below command.
pip install cmake
Step 3:
conda install -c conda-forge dlib

Note you can find few other dlib packages, but the above one will works perfectly with this procedure.

dlib will be successfully installed.

Find and replace words/lines in a file

You can use Java's Scanner class to parse words of a file and process them in your application, and then use a BufferedWriter or FileWriter to write back to the file, applying the changes.

I think there is a more efficient way of getting the iterator's position of the scanner at some point, in order to better implement editting. But since files are either open for reading, or writing, I'm not sure regarding that.

In any case, you can use libraries already available for parsing of XML files, which have all of this implemented already and will allow you to do what you want easily.