Programs & Examples On #Child objects

How to save a data.frame in R?

Let us say you have a data frame you created and named "Data_output", you can simply export it to same directory by using the following syntax.

write.csv(Data_output, "output.csv", row.names = F, quote = F)

credit to Peter and Ilja, UMCG, the Netherlands

Get all child elements

Yes, you can use find_elements_by_ to retrieve children elements into a list. See the python bindings here: http://selenium-python.readthedocs.io/locating-elements.html

Example HTML:

<ul class="bar">
    <li>one</li>
    <li>two</li>
    <li>three</li>
</ul>

You can use the find_elements_by_ like so:

parentElement = driver.find_element_by_class_name("bar")
elementList = parentElement.find_elements_by_tag_name("li")

If you want help with a specific case, you can edit your post with the HTML you're looking to get parent and children elements from.

How to print a float with 2 decimal places in Java?

One issue that had me for an hour or more, on DecimalFormat- It handles double and float inputs differently. Even change of RoundingMode did not help. I am no expert but thought it may help someone like me. Ended up using Math.round instead. See below:

    DecimalFormat df = new DecimalFormat("#.##");
    double d = 0.7750;
    System.out.println(" Double 0.7750 -> " +Double.valueOf(df.format(d)));
    float f = 0.7750f;
    System.out.println(" Float 0.7750f -> "+Float.valueOf(df.format(f)));
    // change the RoundingMode
    df.setRoundingMode(RoundingMode.HALF_UP);
    System.out.println(" Rounding Up Double 0.7750 -> " +Double.valueOf(df.format(d)));
    System.out.println(" Rounding Up Float 0.7750f -> " +Float.valueOf(df.format(f)));

Output:

Double 0.7750 -> 0.78
Float 0.7750f -> 0.77

Rounding Up Double 0.7750 -> 0.78
Rounding Up Float 0.7750f -> 0.77

pandas loc vs. iloc vs. at vs. iat?

loc: only work on index
iloc: work on position
at: get scalar values. It's a very fast loc
iat: Get scalar values. It's a very fast iloc

Also,

at and iat are meant to access a scalar, that is, a single element in the dataframe, while loc and iloc are ments to access several elements at the same time, potentially to perform vectorized operations.

http://pyciencia.blogspot.com/2015/05/obtener-y-filtrar-datos-de-un-dataframe.html

Call int() function on every list element?

Another way to make it in Python 3:

numbers = [*map(int, numbers)]

Changing the image source using jQuery

Just an addition, to make it even more tiny:

$('#imgId').click(function(){
    $(this).attr("src",$(this).attr('src') == 'img1_on.gif' ? 'img1_off.gif':'img1_on.gif');
});

Resize image proportionally with CSS?

img{
    max-width:100%;
    object-fit: scale-down;
}

works for me. It scales down larger images to fit in the box, but leaves smaller images their original size.

window.history.pushState refreshing the browser

The short answer is that history.pushState (not History.pushState, which would throw an exception, the window part is optional) will never do what you suggest.

If pages are refreshing, then it is caused by other things that you are doing (for example, you might have code running that goes to a new location in the case of the address bar changing).

history.pushState({urlPath:'/page2.php'},"",'/page2.php') works exactly like it is supposed to in the latest versions of Chrome, IE and Firefox for me and my colleagues.

In fact you can put whatever you like into the function: history.pushState({}, '', 'So long and thanks for all the fish.not a real file').

If you post some more code (with special attention for code nearby the history.pushState and anywhere document.location is used), then we'll be more than happy to help you figure out where exactly this issue is coming from.

If you post more code, I'll update this answer (I have your question favourited) :).

Execute SQL script to create tables and rows

If you have password for your dB then

mysql -u <username> -p <DBName> < yourfile.sql

How to build a Horizontal ListView with RecyclerView?

Is there a better way to implement this now with Recyclerview now?

Yes.

When you use a RecyclerView, you need to specify a LayoutManager that is responsible for laying out each item in the view. The LinearLayoutManager allows you to specify an orientation, just like a normal LinearLayout would.

To create a horizontal list with RecyclerView, you might do something like this:

LinearLayoutManager layoutManager
    = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);

RecyclerView myList = (RecyclerView) findViewById(R.id.my_recycler_view);
myList.setLayoutManager(layoutManager);

constant pointer vs pointer on a constant value

I will explain it verbally first and then with an example:

A pointer object can be declared as a const pointer or a pointer to a const object (or both):

const pointer cannot be reassigned to point to a different object from the one it is initially assigned, but it can be used to modify the object that it points to (called the "pointee").
Reference variables are thus an alternate syntax for constpointers.

A pointer to a const object, on the other hand, can be reassigned to point to another object of the same type or of a convertible type, but it cannot be used to modify any object.

const pointer to a const object can also be declared and can neither be used to modify the pointee nor be reassigned to point to another object.

Example:

void Foo( int * ptr,
         int const * ptrToConst,
         int * const constPtr,
         int const * const constPtrToConst ) 
{ 
    *ptr = 0; // OK: modifies the "pointee" data 
    ptr = 0; // OK: modifies the pointer 

    *ptrToConst = 0; // Error! Cannot modify the "pointee" data
     ptrToConst = 0; // OK: modifies the pointer 

    *constPtr = 0; // OK: modifies the "pointee" data 
    constPtr = 0; // Error! Cannot modify the pointer 

    *constPtrToConst = 0; // Error! Cannot modify the "pointee" data 
    constPtrToConst = 0; // Error! Cannot modify the pointer 
}

Happy to help! Good Luck!

how to pass value from one php page to another using session

Solution using just POST - no $_SESSION

page1.php

<form action="page2.php" method="post">
    <textarea name="textarea1" id="textarea1"></textarea><br />
    <input type="submit" value="submit" />
</form>

page2.php

<?php
    // this page outputs the contents of the textarea if posted
    $textarea1 = ""; // set var to avoid errors
    if(isset($_POST['textarea1'])){
        $textarea1 = $_POST['textarea1']
    }
?>
<textarea><?php echo $textarea1;?></textarea>

Solution using $_SESSION and POST

page1.php

<?php

    session_start(); // needs to be before anything else on page to use $_SESSION
    $textarea1 = "";
    if(isset($_POST['textarea1'])){
        $_SESSION['textarea1'] = $_POST['textarea1'];
    }

?>


<form action="page1.php" method="post">
    <textarea name="textarea1" id="textarea1"></textarea><br />
    <input type="submit" value="submit" />
</form>
<br /><br />
<a href="page2.php">Go to page2</a>

page2.php

<?php
    session_start(); // needs to be before anything else on page to use $_SESSION
    // this page outputs the textarea1 from the session IF it exists
    $textarea1 = ""; // set var to avoid errors
    if(isset($_SESSION['textarea1'])){
        $textarea1 = $_SESSION['textarea1']
    }
?>
<textarea><?php echo $textarea1;?></textarea>

WARNING!!! - This contains no validation!!!

Android: how to create Switch case from this?

switch(position) {
    case 0:
        setContentView(R.layout.xml0);
        break;
    case 1:
        setContentView(R.layout.xml1);
        break;
    default:
        setContentView(R.layout.default);
        break;
}

i hope this will do the job!

Setting the correct PATH for Eclipse

For me none worked. I compared my existing eclipse.ini with a new one and started removing options and testing if eclipse worked.

The only option that prevented eclipse from starting was -XX:+UseParallelGC, so I removed it and voilá!

Mocking a method to throw an exception (moq), but otherwise act like the mocked object?

This is how I managed to do what I was trying to do:

[Test]
public void TransferHandlesDisconnect()
{
    // ... set up config here
    var methodTester = new Mock<Transfer>(configInfo);
    methodTester.CallBase = true;
    methodTester
        .Setup(m => 
            m.GetFile(
                It.IsAny<IFileConnection>(), 
                It.IsAny<string>(), 
                It.IsAny<string>()
            ))
        .Throws<System.IO.IOException>();

    methodTester.Object.TransferFiles("foo1", "foo2");
    Assert.IsTrue(methodTester.Object.Status == TransferStatus.TransferInterrupted);
}

If there is a problem with this method, I would like to know; the other answers suggest I am doing this wrong, but this was exactly what I was trying to do.

TypeScript, Looping through a dictionary

How about this?

for (let [key, value] of Object.entries(obj)) {
    ...
}

Replace input type=file by an image

You can put an image instead, and do it like this:

HTML:

<img src="/images/uploadButton.png" id="upfile1" style="cursor:pointer" />
<input type="file" id="file1"  name="file1" style="display:none" />

JQuery:

$("#upfile1").click(function () {
    $("#file1").trigger('click');
});

CAVEAT: In IE9 and IE10 if you trigger the onclick in a file input via javascript the form gets flagged as 'dangerous' and cannot be submmited with javascript, no sure if it can be submitted traditionaly.

Twitter Bootstrap button click to toggle expand/collapse text section above button

Elaborating a bit more on Taylor Gautier's reply (sorry, I dont have enough reputation to add a comment), I'd reply to Dean Richardson on how to do what he wanted, without any additional JS code. Pure CSS.

You would replace his .btn with the following:

<a class="btn showdetails" data-toggle="collapse" data-target="#viewdetails"></a>

And add a small CSS for when the content is displayed:

.in.collapse+a.btn.showdetails:before { 
    content:'Hide details «';
}
.collapse+a.btn.showdetails:before { 
    content:'Show details »'; 
}

Here is his modified example

How to echo or print an array in PHP?

Human readable: (eg. can be log to text file..)

print_r( $arr_name , TRUE);

How to prevent downloading images and video files from my website?

Don't post them to your site.

Otherwise it is not possible.

Error:Conflict with dependency 'com.google.code.findbugs:jsr305'

The problem, as stated in your logs, is 2 dependencies trying to use different versions of 3rd dependency. Add one of the following to the app-gradle file:

androidTestCompile 'com.google.code.findbugs:jsr305:2.0.1'
androidTestCompile 'com.google.code.findbugs:jsr305:1.3.9'

Check if record exists from controller in Rails

I would do it this way if you needed an instance variable of the object to work with:

if @business = Business.where(:user_id => current_user.id).first
  #Do stuff
else
  #Do stuff
end

What's the difference between Cache-Control: max-age=0 and no-cache?

One thing that (surprisingly) hasn't been mentioned is that a request can explicitly indicate that it will accept stale data, using the max-stale directive. In that case, if the server responded with max-age=0, the cache would merely consider the response stale, and would be free to use it to satisfy the client's request [which asked for potentially-stale data]. By contrast, if the server sends no-cache that really does trump any request by the client (with max-stale) for stale data, as the cache MUST revalidate.

Must JDBC Resultsets and Statements be closed separately although the Connection is closed afterwards?

From the javadocs:

When a Statement object is closed, its current ResultSet object, if one exists, is also closed.

However, the javadocs are not very clear on whether the Statement and ResultSet are closed when you close the underlying Connection. They simply state that closing a Connection:

Releases this Connection object's database and JDBC resources immediately instead of waiting for them to be automatically released.

In my opinion, always explicitly close ResultSets, Statements and Connections when you are finished with them as the implementation of close could vary between database drivers.

You can save yourself a lot of boiler-plate code by using methods such as closeQuietly in DBUtils from Apache.

Should we @Override an interface's method implementation?

You should always annotate methods with @Override if it's available.

In JDK 5 this means overriding methods of superclasses, in JDK 6, and 7 it means overriding methods of superclasses, and implementing methods of interfaces. The reason, as mentioned previously, is it allows the compiler to catch errors where you think you are overriding (or implementing) a method, but are actually defining a new method (different signature).

The equals(Object) vs. equals(YourObject) example is a standard case in point, but the same argument can be made for interface implementations.

I'd imagine the reason it's not mandatory to annotate implementing methods of interfaces is that JDK 5 flagged this as a compile error. If JDK 6 made this annotation mandatory, it would break backwards compatibility.

I am not an Eclipse user, but in other IDEs (IntelliJ), the @Override annotation is only added when implementing interface methods if the project is set as a JDK 6+ project. I would imagine that Eclipse is similar.

However, I would have preferred to see a different annotation for this usage, maybe an @Implements annotation.

Another git process seems to be running in this repository

I got this error while pod update. I solved it by deleting the index.lock file in cocoapods's .git directory.

rm -f /Users/my_user_name/.cocoapods/repos/master/.git/index.lock

It might help someone.

javascript: using a condition in switch case

Your code does not work because it is not doing what you are expecting it to do. Switch blocks take in a value, and compare each case to the given value, looking for equality. Your comparison value is an integer, but most of your case expressions resolve to a boolean value.

So, for example, say liCount = 2. Your first case will not match, because 2 != 0. Your second case, (liCount<=5 && liCount>0) evaluates to true, but 2 != true, so this case will not match either.

For this reason, as many others have said, you should use a series of if...then...else if blocks to do this.

Bootstrap 3 hidden-xs makes row narrower

.row {
    margin-right: 15px;
}

throw this in your CSS

libxml install error using pip

I work on a Windows machine. And here are some pointers for successful installation of lxml (with python 2.6 and later).

Have the following installed:

  1. MingGW.
  2. libxml2 version 2.7.0 or later.
  3. libxslt version 1.1.23 or later.

All are not available at a pip install.

libxml2's windows binary is found here.

libxslt is found here.

After you are done with the above two,

do : pip install lxml.

Another workaround is using the stable releases from PyPI or the unofficial Windows binaries by Christoph Gohlke (found here).

How can I include all JavaScript files in a directory via JavaScript file?

It can be done fully client side, but all javascript file names must be specified. For example, as array items:

function loadScripts(){
   var directory = 'script/';
   var extension = '.js';
   var files = ['model', 'view', 'controller'];  
   for (var file of files){ 
       var path = directory + file + extension; 
       var script = document.createElement("script");
       script.src = path;
       document.body.appendChild(script);
   } 
 }

How to send email by using javascript or jquery

You can send Email by Jquery just follow these steps 

include this link : <script src="https://smtpjs.com/v3/smtp.js"></script>
after that use this code :

$( document ).ready(function() {
 Email.send({
Host : "smtp.yourisp.com",
Username : "username",
Password : "password",
To : '[email protected]',
From : "[email protected]",
Subject : "This is the subject",
Body : "And this is the body"}).then( message => alert(message));});

How to communicate between Docker containers via "hostname"

The new networking feature allows you to connect to containers by their name, so if you create a new network, any container connected to that network can reach other containers by their name. Example:

1) Create new network

$ docker network create <network-name>       

2) Connect containers to network

$ docker run --net=<network-name> ...

or

$ docker network connect <network-name> <container-name>

3) Ping container by name

docker exec -ti <container-name-A> ping <container-name-B> 

64 bytes from c1 (172.18.0.4): icmp_seq=1 ttl=64 time=0.137 ms
64 bytes from c1 (172.18.0.4): icmp_seq=2 ttl=64 time=0.073 ms
64 bytes from c1 (172.18.0.4): icmp_seq=3 ttl=64 time=0.074 ms
64 bytes from c1 (172.18.0.4): icmp_seq=4 ttl=64 time=0.074 ms

See this section of the documentation;

Note: Unlike legacy links the new networking will not create environment variables, nor share environment variables with other containers.

This feature currently doesn't support aliases

How to post a file from a form with Axios

This works for me, I hope helps to someone.

var frm = $('#frm');
let formData = new FormData(frm[0]);
axios.post('your-url', formData)
    .then(res => {
        console.log({res});
    }).catch(err => {
        console.error({err});
    });

Regex for numbers only

If you need to tolerate decimal point and thousand marker

var regex = new Regex(@"^-?[0-9][0-9,\.]+$");

You will need a "-", if the number can go negative.

How to select between brackets (or quotes or ...) in Vim?

A simple keymap in vim would solve this issue. map viq F”lvf”hh This above command maps viq to the keys to search between quotes. Replace " with any character and create your keymaps. Stick this in vimrc during startup and you should be able to use it everytime.

How do I add Git version control (Bitbucket) to an existing source code folder?

User johannes told you how to do add existing files to a Git repository in a general situation. Because you talk about Bitbucket, I suggest you do the following:

  1. Create a new repository on Bitbucket (you can see a Create button on the top of your profile page) and you will go to this page:

    Create repository on Bitbucket

  2. Fill in the form, click next and then you automatically go to this page:

    Create repository from scratch or add existing files

  3. Choose to add existing files and you go to this page:

    Enter image description here

  4. You use those commands and you upload the existing files to Bitbucket. After that, the files are online.

How to display scroll bar onto a html table

Worth noting, that depending on your purpose (mine was the autofill results of a searchbar) you may want the height to be changeable, and for the scrollbar to only exist if the height exceeds that.

If you want that, replace height: x; with max-height: x;, and overflow:scroll with overflow:auto.

Additionally, you can use overflow-x and overflow-y if you want, and obviously the same thing works horizontally with width : x;

How to name an object within a PowerPoint slide?

Click Insert ->Object->Create from file ->Browse.

Once the file is selected choose the "Change icon" option and you will be able to rename the file and change the icon if you wish.

Hope this helps!

How to remove rows with any zero value

I would probably go with Joran's suggestion of replacing 0's with NAs and then using the built in functions you mentioned. If you can't/don't want to do that, one approach is to use any() to find rows that contain 0's and subset those out:

set.seed(42)
#Fake data
x <- data.frame(a = sample(0:2, 5, TRUE), b = sample(0:2, 5, TRUE))
> x
  a b
1 2 1
2 2 2
3 0 0
4 2 1
5 1 2
#Subset out any rows with a 0 in them
#Note the negation with ! around the apply function
x[!(apply(x, 1, function(y) any(y == 0))),]
  a b
1 2 1
2 2 2
4 2 1
5 1 2

To implement Joran's method, something like this should get you started:

x[x==0] <- NA

How to make connection to Postgres via Node.js

Here is an example I used to connect node.js to my Postgres database.

The interface in node.js that I used can be found here https://github.com/brianc/node-postgres

var pg = require('pg');
var conString = "postgres://YourUserName:YourPassword@localhost:5432/YourDatabase";

var client = new pg.Client(conString);
client.connect();

//queries are queued and executed one after another once the connection becomes available
var x = 1000;

while (x > 0) {
    client.query("INSERT INTO junk(name, a_number) values('Ted',12)");
    client.query("INSERT INTO junk(name, a_number) values($1, $2)", ['John', x]);
    x = x - 1;
}

var query = client.query("SELECT * FROM junk");
//fired after last row is emitted

query.on('row', function(row) {
    console.log(row);
});

query.on('end', function() {
    client.end();
});



//queries can be executed either via text/parameter values passed as individual arguments
//or by passing an options object containing text, (optional) parameter values, and (optional) query name
client.query({
    name: 'insert beatle',
    text: "INSERT INTO beatles(name, height, birthday) values($1, $2, $3)",
    values: ['George', 70, new Date(1946, 02, 14)]
});

//subsequent queries with the same name will be executed without re-parsing the query plan by postgres
client.query({
    name: 'insert beatle',
    values: ['Paul', 63, new Date(1945, 04, 03)]
});
var query = client.query("SELECT * FROM beatles WHERE name = $1", ['john']);

//can stream row results back 1 at a time
query.on('row', function(row) {
    console.log(row);
    console.log("Beatle name: %s", row.name); //Beatle name: John
    console.log("Beatle birth year: %d", row.birthday.getYear()); //dates are returned as javascript dates
    console.log("Beatle height: %d' %d\"", Math.floor(row.height / 12), row.height % 12); //integers are returned as javascript ints
});

//fired after last row is emitted
query.on('end', function() {
    client.end();
});

UPDATE:- THE query.on function is now deprecated and hence the above code will not work as intended. As a solution for this look at:- query.on is not a function

Batch file to map a drive when the folder name contains spaces

net use "m:\Server01\my folder" /USER:mynetwork\Administrator "Mypassword" /persistent:yes 

does not work?

Wrapping text inside input type="text" element HTML/CSS

That is the textarea's job - for multiline text input. The input won't do it; it wasn't designed to do it.

So use a textarea. Besides their visual differences, they are accessed via JavaScript the same way (use value property).

You can prevent newlines being entered via the input event and simply using a replace(/\n/g, '').

How to pass values arguments to modal.show() function in Bootstrap

I want to share how I did this. I spent the last few days rattling my head with how to pass a couple of parameters to the bootstrap modal dialog. After much head bashing, I came up with a rather simple way of doing this.

Here is my modal code:

<div class="modal fade" id="editGroupNameModal" role="dialog">
  <div class="modal-dialog">
    <div class="modal-content">
      <div id="editGroupName" class="modal-header">Enter new name for group </div>
        <div class="modal-body">
          <%= form_tag( { action: 'update_group', port: portnum } ) do %>
          <%= text_field_tag( :gid, "", { type: "hidden" })  %>
          <div class="input-group input-group-md">
          <span class="input-group-addon" style="font-size: 16px; padding: 3;" >Name</span>
          <%= text_field_tag( :gname, "", { placeholder: "New name goes here", class: "form-control", aria: {describedby: "basic-addon1"}})  %>
        </div>
        <div class="modal-footer">
          <%= submit_tag("Submit") %>
        </div>
        <% end %>
      </div>
    </div>
  </div>
</div>

And here is the simple javascript to change the gid, and gname input values:

function editGroupName(id, name) {
    $('input#gid').val(id);
    $('input#gname.form-control').val(name);
  }

I just used the onclick event in a link:

//                                                                              &#39; is single quote
//                                                                                   ('1', 'admin')
<a data-toggle="modal" data-target="#editGroupNameModal" onclick="editGroupName(&#39;1&#39;, &#39;admin&#39;); return false;" href="#">edit</a>

The onclick fires first, changing the value property of the input boxes, so when the dialog pops up, values are in place for the form to submit.

I hope this helps someone someday. Cheers.

How do you get the process ID of a program in Unix or Linux using Python?

With psutil:

(can be installed with [sudo] pip install psutil)

import psutil

# Get current process pid
current_process_pid = psutil.Process().pid
print(current_process_pid)  # e.g 12971

# Get pids by program name
program_name = 'chrome'
process_pids = [process.pid for process in psutil.process_iter() if process.name == program_name]
print(process_pids)  # e.g [1059, 2343, ..., ..., 9645]

How to get a jqGrid selected row cells value

You can use in this manner also

var rowId =$("#list").jqGrid('getGridParam','selrow');  
var rowData = jQuery("#list").getRowData(rowId);
var colData = rowData['UserId'];   // perticuler Column name of jqgrid that you want to access

Get specific line from text file using just shell script

If for example you want to get the lines 10 to 20 of a file you can use each of these two methods:

head -n 20 york.txt | tail -11

or

sed -n '10,20p' york.txt 

p in above command stands for printing.

Here's what you'll see: enter image description here

How to change the order of DataFrame columns?

import numpy as np
import pandas as pd
df = pd.DataFrame()
column_names = ['x','y','z','mean']
for col in column_names: 
    df[col] = np.random.randint(0,100, size=10000)

You can try out the following solutions :

Solution 1:

df = df[ ['mean'] + [ col for col in df.columns if col != 'mean' ] ]

Solution 2:


df = df[['mean', 'x', 'y', 'z']]

Solution 3:

col = df.pop("mean")
df = df.insert(0, col.name, col)

Solution 4:

df.set_index(df.columns[-1], inplace=True)
df.reset_index(inplace=True)

Solution 5:

cols = list(df)
cols = [cols[-1]] + cols[:-1]
df = df[cols]

solution 6:

order = [1,2,3,0] # setting column's order
df = df[[df.columns[i] for i in order]]

Time Comparison:

Solution 1:

CPU times: user 1.05 ms, sys: 35 µs, total: 1.08 ms Wall time: 995 µs

Solution 2:

CPU times: user 933 µs, sys: 0 ns, total: 933 µs Wall time: 800 µs

Solution 3:

CPU times: user 0 ns, sys: 1.35 ms, total: 1.35 ms Wall time: 1.08 ms

Solution 4:

CPU times: user 1.23 ms, sys: 45 µs, total: 1.27 ms Wall time: 986 µs

Solution 5:

CPU times: user 1.09 ms, sys: 19 µs, total: 1.11 ms Wall time: 949 µs

Solution 6:

CPU times: user 955 µs, sys: 34 µs, total: 989 µs Wall time: 859 µs

How do I select the "last child" with a specific class name in CSS?

$('.class')[$(this).length - 1] 

or

$( "p" ).last().addClass( "selected" );

find all subsets that sum to a particular value

The usual DP solution is true for the problem.

One optimization you may do, is to keep a count of how many solutions exist for the particular sum rather than the actual sets that make up that sum...

Difference between hamiltonian path and euler path

Euler path is a graph using every edge(NOTE) of the graph exactly once. Euler circuit is a euler path that returns to it starting point after covering all edges.

While hamilton path is a graph that covers all vertex(NOTE) exactly once. When this path returns to its starting point than this path is called hamilton circuit.

How can I check if char* variable points to empty string?

Check the pointer for NULL and then using strlen to see if it returns 0.
NULL check is important because passing NULL pointer to strlen invokes an Undefined Behavior.

Django optional url parameters

Use ? work well, you can check on pythex. Remember to add the parameters *args and **kwargs in the definition of the view methods

url('project_config/(?P<product>\w+)?(/(?P<project_id>\w+/)?)?', tool.views.ProjectConfig, name='project_config')

Capturing TAB key in text box

Even if you capture the keydown/keyup event, those are the only events that the tab key fires, you still need some way to prevent the default action, moving to the next item in the tab order, from occurring.

In Firefox you can call the preventDefault() method on the event object passed to your event handler. In IE, you have to return false from the event handle. The JQuery library provides a preventDefault method on its event object that works in IE and FF.

<body>
<input type="text" id="myInput">
<script type="text/javascript">
    var myInput = document.getElementById("myInput");
    if(myInput.addEventListener ) {
        myInput.addEventListener('keydown',this.keyHandler,false);
    } else if(myInput.attachEvent ) {
        myInput.attachEvent('onkeydown',this.keyHandler); /* damn IE hack */
    }

    function keyHandler(e) {
        var TABKEY = 9;
        if(e.keyCode == TABKEY) {
            this.value += "    ";
            if(e.preventDefault) {
                e.preventDefault();
            }
            return false;
        }
    }
</script>
</body>

How to edit the legend entry of a chart in Excel?

Left Click on chart. «PivotTable Field List» will appear on right. On the right down quarter of PivotTable Field List (S Values), you see the names of the legends. Left Click on the legend name. Left Click on the «Value field settings». At the top there is «Source Name». You can’t change it. Below there is «Custom Name». Change the Custom Name as you wish. Now the legend name on the chart has the new name you gave.

ASP.NET MVC3 - textarea with @Html.EditorFor

@Html.TextAreaFor(model => model.Text)

Javac is not found

  1. Go to my computer;
  2. Right click properties;
  3. Go to advanced system settings;
  4. Go to environment variables;
  5. In user variables for user click on new(top new button, not on system variables);
  6. Set variable name as: Path
  7. Set the value of that variable to: C:\Program Files\Java\jdk1.7.0_76\bin
  8. Click ok;
  9. Click ok;
  10. Click ok.

Now you're set. Type javac in cmd. All javac options will be displayed.

CSS background image in :after element

As AlienWebGuy said, you can use background-image. I'd suggest you use background, but it will need three more properties after the URL:

background: url("http://www.gentleface.com/i/free_toolbar_icons_16x16_black.png") 0 0 no-repeat;

Explanation: the two zeros are x and y positioning for the image; if you want to adjust where the background image displays, play around with these (you can use both positive and negative values, e.g: 1px or -1px).

No-repeat says you don't want the image to repeat across the entire background. This can also be repeat-x and repeat-y.

Javascript callback when IFRAME is finished loading?

I've had exactly the same problem in the past and the only way I found to fix it was to add the callback into the iframe page. Of course that only works when you have control over the iframe content.

javascript: Disable Text Select

Just use this css method:

body{
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

You can find the same answer here: How to disable text selection highlighting using CSS?

Change background position with jQuery

You guys are complicating things. You can simple do this from CSS.

#carousel li { background-position:0px 0px; }
#carousel li:hover { background-position:100px 0px; }

How to completely uninstall Android Studio from windows(v10)?

Uninstall your android studio in control panel and remove all data in your file manager about android studio.

What is the difference between __str__ and __repr__?

One aspect that is missing in other answers. It's true that in general the pattern is:

  • Goal of __str__: human-readable
  • Goal of __repr__: unambiguous, possibly machine-readable via eval

Unfortunately, this differentiation is flawed, because the Python REPL and also IPython use __repr__ for printing objects in a REPL console (see related questions for Python and IPython). Thus, projects which are targeted for interactive console work (e.g., Numpy or Pandas) have started to ignore above rules and provide a human-readable __repr__ implementation instead.

Customize list item bullets using CSS

You mean altering the size of the bullet, I assume? I believe this is tied to the font-size of the li tag. Thus, you can blow up the font-size for the LI, then reduce it for an element contained inside. Kind of sucks to add the extra markup - but something like:

li {font-size:omgHuge;}
li span {font-size:mehNormal;}

Alternately, you can specify an image file for your list bullets, that could be as big as you want:

ul{
  list-style: square url("38specialPlusP.gif");
 }

See: http://www.w3schools.com/css/css_list.asp

Can I store images in MySQL

You'll need to save as a blob, LONGBLOB datatype in mysql will work.

Ex:

CREATE TABLE 'test'.'pic' (
    'idpic' INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
    'caption' VARCHAR(45) NOT NULL,
    'img' LONGBLOB NOT NULL,
  PRIMARY KEY ('idpic')
)

As others have said, its a bad practice but it can be done. Not sure if this code would scale well, though.

How to run SUDO command in WinSCP to transfer files from Windows to linux

There is an option in WinSCP that does exactly what you are looking for:

enter image description here

enter image description here

Is there a Python equivalent of the C# null-coalescing operator?

In addition to Juliano's answer about behavior of "or": it's "fast"

>>> 1 or 5/0
1

So sometimes it's might be a useful shortcut for things like

object = getCachedVersion() or getFromDB()

Adding and removing style attribute from div with jquery

The easy way to handle this (and best HTML solution to boot) is to set up classes that have the styles you want to use. Then it's a simple matter of using addClass() and removeClass(), or even toggleClass().

$('#voltaic_holder').addClass('shiny').removeClass('dull');

or even

$('#voltaic_holder').toggleClass('shiny dull');

How do I get a list of folders and sub folders without the files?

 Displays a list of files and subdirectories in a directory.

 DIR [ drive:][path][filename] [/A[[:]attributes]] [/B] [/C] [/D] [/L] [/N]
  [/O[[:]sortorder]] [/P] [/Q] [/R] [/S] [/T[[:]timefield]] [/W] [/X] [/4]

  [drive:][path][filename]
          Specifies drive, directory, and/or files to list.

  /A          Displays files with specified attributes.
  attributes   D  Directories                R  Read-only files
           H  Hidden files               A  Files ready for archiving
           S  System files               I  Not content indexed files
           L  Reparse Points             -  Prefix meaning not

just set type of desired file attribute, in your case /A:D (directory)

dir /s/b/o:n/A:D > f.txt

How to implement 2D vector array?

vector<int> adj[n]; // where n is number of rows in 2d vector.

How to add,set and get Header in request of HttpClient?

You can test-drive this code exactly as is using the public GitHub API (don't go over the request limit):

public class App {

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

        CloseableHttpClient client = HttpClients.custom().build();

        // (1) Use the new Builder API (from v4.3)
        HttpUriRequest request = RequestBuilder.get()
                .setUri("https://api.github.com")
                // (2) Use the included enum
                .setHeader(HttpHeaders.CONTENT_TYPE, "application/json")
                // (3) Or your own
                .setHeader("Your own very special header", "value")
                .build();

        CloseableHttpResponse response = client.execute(request);

        // (4) How to read all headers with Java8
        List<Header> httpHeaders = Arrays.asList(response.getAllHeaders());
        httpHeaders.stream().forEach(System.out::println);

        // close client and response
    }
}

How to resolve git's "not something we can merge" error

If the string containing the reference is produced by another Git command (or any other shell command for that matter), make sure that it doesn't contain a return carriage at the end. You will have to strip it before passing the string to "git merge".

Note that it's pretty obvious when this happens, because the error message in on 2 lines:

merge: 26d8e04b29925ea5b59cb50501ab5a14dd35f0f9
 - not something we can merge

How to load a controller from another controller in codeigniter?

you cannot call a controller method from another controller directly

my solution is to use inheritances and extend your controller from the library controller

class Controller1 extends CI_Controller {

    public function index() {
        // some codes here
    }

    public function methodA(){
        // code here
    }
}

in your controller we call it Mycontoller it will extends Controller1

include_once (dirname(__FILE__) . "/controller1.php");

class Mycontroller extends Controller1 {

    public function __construct() {
        parent::__construct();
    }

    public function methodB(){
        // codes....
    }
}

and you can call methodA from mycontroller

http://example.com/mycontroller/methodA

http://example.com/mycontroller/methodB

this solution worked for me

Tainted canvases may not be exported

For security reasons, your local drive is declared to be "other-domain" and will taint the canvas.

(That's because your most sensitive info is likely on your local drive!).

While testing try these workarounds:

  • Put all page related files (.html, .jpg, .js, .css, etc) on your desktop (not in sub-folders).

  • Post your images to a site that supports cross-domain sharing (like dropbox.com). Be sure you put your images in dropbox's public folder and also set the cross origin flag when downloading the image (var img=new Image(); img.crossOrigin="anonymous" ...)

  • Install a webserver on your development computer (IIS and PHP web servers both have free editions that work nicely on a local computer).

How to use JUnit to test asynchronous processes

It's worth mentioning that there is very useful chapter Testing Concurrent Programs in Concurrency in Practice which describes some unit testing approaches and gives solutions for issues.

Force page scroll position to top at page refresh in HTML

This is one of the best way to do so:

_x000D_
_x000D_
<script>
$(window).on('beforeunload', function() {
  $('body').hide();
  $(window).scrollTop(0);
});
</script>
_x000D_
_x000D_
_x000D_

What does API level mean?

API level is basically the Android version. Instead of using the Android version name (eg 2.0, 2.3, 3.0, etc) an integer number is used. This number is increased with each version. Android 1.6 is API Level 4, Android 2.0 is API Level 5, Android 2.0.1 is API Level 6, and so on.

Extract Month and Year From Date in R

The data.table package introduced the IDate class some time ago and zoo-package-like functions to retrieve months, days, etc (Check ?IDate). so, you can extract the desired info now in the following ways:

require(data.table)
df <- data.frame(id = 1:3,
                 date = c("2004-02-06" , "2006-03-14" , "2007-07-16"))
setDT(df)
df[ , date := as.IDate(date) ] # instead of as.Date()
df[ , yrmn := paste0(year(date), '-', month(date)) ]
df[ , yrmn2 := format(date, '%Y-%m') ]

Select mySQL based only on month and year

No one seems to be talking about performance so I tested the two most popular answers on a sample database from Mysql. The table has 2.8M rows with structure

CREATE TABLE `salaries` (
  `emp_no` int(11) NOT NULL,
  `salary` int(11) NOT NULL,
  `from_date` date NOT NULL,
  `to_date` date NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

ALTER TABLE `salaries`
  ADD PRIMARY KEY (`emp_no`,`from_date`);

Here are the tests performed and results

SELECT * FROM `salaries` WHERE YEAR(from_date) = 1992 AND MONTH(from_date) = 6
12339 results
-----------------
11.5 ms 
12.1 ms
09.5 ms
07.5 ms
10.2 ms
-----------------
10.2 ms Avg
-----------------


SELECT * FROM `salaries` WHERE from_date BETWEEN '1992-06-01' AND '1992-06-31'
-----------------
10.0 ms
10.8 ms
09.5 ms
09.0 ms
08.3 ms
-----------------
09.5 ms Avg
-----------------


SELECT * FROM `salaries` WHERE YEAR(to_date) = 1992 AND MONTH(to_date) = 6
10887 results
-----------------
10.2 ms
11.7 ms
11.8 ms
12.4 ms
09.6 ms
-----------------
11.1 ms Avg
-----------------


SELECT * FROM `salaries` WHERE to_date BETWEEN '1992-06-01' AND '1992-06-31'
-----------------
09.0 ms
07.5 ms
10.6 ms
11.7 ms
12.0 ms
-----------------
10.2 ms Avg
-----------------

My Conclusions

  1. BETWEEN was slightly better on both indexed and unindexed column.
  2. The unindexed column was marginally slower than the indexed column.

Is JavaScript guaranteed to be single-threaded?

I would say that the specification does not prevent someone from creating an engine that runs javascript on multiple threads, requiring the code to perform synchronization for accessing shared object state.

I think the single-threaded non-blocking paradigm came out of the need to run javascript in browsers where ui should never block.

Nodejs has followed the browsers' approach.

Rhino engine however, supports running js code in different threads. The executions cannot share context, but they can share scope. For this specific case the documentation states:

..."Rhino guarantees that accesses to properties of JavaScript objects are atomic across threads, but doesn't make any more guarantees for scripts executing in the same scope at the same time.If two scripts use the same scope simultaneously, the scripts are responsible for coordinating any accesses to shared variables."

From reading Rhino documentation I conclude that that it can be possible for someone to write a javascript api that also spawns new javascript threads, but the api would be rhino-specific (e.g. node can only spawn a new process).

I imagine that even for an engine that supports multiple threads in javascript there should be compatibility with scripts that do not consider multi-threading or blocking.

Concearning browsers and nodejs the way I see it is:

    1. Is all js code executed in a single thread? : Yes.
    1. Can js code cause other threads to run? : Yes.
    1. Can these threads mutate js execution context?: No. But they can (directly/indirectly(?)) append to the event queue from which listeners can mutate execution context. But don't be fooled, listeners run atomically on the main thread again.

So, in case of browsers and nodejs (and probably a lot of other engines) javascript is not multithreaded but the engines themselves are.


Update about web-workers:

The presence of web-workers justifies further that javascript can be multi-threaded, in the sense that someone can create code in javascript that will run on a separate thread.

However: web-workers do not curry the problems of traditional threads who can share execution context. Rules 2 and 3 above still apply, but this time the threaded code is created by the user (js code writer) in javascript.

The only thing to consider is the number of spawned threads, from an efficiency (and not concurrency) point of view. See below:

About thread safety:

The Worker interface spawns real OS-level threads, and mindful programmers may be concerned that concurrency can cause “interesting” effects in your code if you aren't careful.

However, since web workers have carefully controlled communication points with other threads, it's actually very hard to cause concurrency problems. There's no access to non-threadsafe components or the DOM. And you have to pass specific data in and out of a thread through serialized objects. So you have to work really hard to cause problems in your code.


P.S.

Besides theory, always be prepared about possible corner cases and bugs described on the accepted answer

How to create a new column in a select query

select A, B, 'c' as C
from MyTable

How to escape the % (percent) sign in C's printf?

If there are no formats in the string, you can use puts (or fputs):

puts("hello%");

if there is a format in the string:

printf("%.2f%%", 53.2);

As noted in the comments, puts appends a \n to the output and fputs does not.

How can I change NULL to 0 when getting a single value from a SQL function?

ORACLE/PLSQL:

NVL FUNCTION

SELECT NVL(SUM(Price), 0) AS TotalPrice 
FROM Inventory
WHERE (DateAdded BETWEEN @StartDate AND @EndDate)

This SQL statement would return 0 if the SUM(Price) returned a null value. Otherwise, it would return the SUM(Price) value.

What is the purpose and uniqueness SHTML?

SHTML is a file extension that lets the web server know the file should be processed as using Server Side Includes (SSI).

(HTML is...you know what it is, and DHTML is Microsoft's name for Javascript+HTML+CSS or something).

You can use SSI to include a common header and footer in your pages, so you don't have to repeat code as much. Changing one included file updates all of your pages at once. You just put it in your HTML page as per normal.

It's embedded in a standard XML comment, and looks like this:

<!--#include virtual="top.shtml" -->

It's been largely superseded by other mechanisms, such as PHP includes, but some hosting packages still support it and nothing else.

You can read more in this Wikipedia article.

CSS background-size: cover replacement for Mobile Safari

I found a working solution, the following CSS code example is targeting the iPad:

@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) {

    html {  
        height: 100%;
        overflow: hidden;
        background: url('http://url.com/image.jpg') no-repeat top center fixed;
        background-size: cover; 
    }

    body {  
        height:100%;
        overflow: scroll;
        -webkit-overflow-scrolling: touch;
    }

}

Reference link: https://www.jotform.com/answers/565598-Page-background-image-scales-massively-when-form-viewed-on-iPad

Freely convert between List<T> and IEnumerable<T>

List<string> myList = new List<string>();
IEnumerable<string> myEnumerable = myList;
List<string> listAgain = myEnumerable.ToList();

how to loop through each row of dataFrame in pyspark

To "loop" and take advantage of Spark's parallel computation framework, you could define a custom function and use map.

def customFunction(row):

   return (row.name, row.age, row.city)

sample2 = sample.rdd.map(customFunction)

or

sample2 = sample.rdd.map(lambda x: (x.name, x.age, x.city))

The custom function would then be applied to every row of the dataframe. Note that sample2 will be a RDD, not a dataframe.

Map may be needed if you are going to perform more complex computations. If you just need to add a simple derived column, you can use the withColumn, with returns a dataframe.

sample3 = sample.withColumn('age2', sample.age + 2)

org.json.simple.JSONArray cannot be cast to org.json.simple.JSONObject

JSONObject baseReq
LinkedHashMap insert = (LinkedHashMap) baseReq.get("insert");
LinkedHashMap delete = (LinkedHashMap) baseReq.get("delete");

How can I find the dimensions of a matrix in Python?

The correct answer is the following:

import numpy 
numpy.shape(a)

Install-Module : The term 'Install-Module' is not recognized as the name of a cmdlet

I didn't have the NuGet Package Provider, you can check running Get-PackageProvider:

PS C:\WINDOWS\system32> Get-PackageProvider 

Name                     Version          DynamicOptions                                                                                                                 
----                     -------          --------------                                                                                                                 
msi                      3.0.0.0          AdditionalArguments                                                                                                            
msu                      3.0.0.0                                                                                                                                         
NuGet  <NOW INSTALLED>   2.8.5.208        Destination, ...                             

The solution was installing it by running this command:

Install-PackageProvider -Name NuGet -MinimumVersion 2.8.5.201 -Force

If that fails with the error below you can copy/paste the NuGet folder from another PC (admin needed): C:\Program Files\PackageManagement\ProviderAssemblies\NuGet:

WARNING: Unable to download from URI 'https://onegetcdn.azureedge.net/providers/Microsoft.PackageManagement.NuGetProvider-2.8.5.208.dll' to ''.
WARNING: Failed to bootstrap provider 'https://onegetcdn.azureedge.net/providers/nuget-2.8.5.208.package.swidtag'.
WARNING: Failed to bootstrap provider 'nuget'.
WARNING: The specified PackageManagement provider 'NuGet' is not available.
PackageManagement\Install-PackageProvider : Unable to download from URI 
'https://onegetcdn.azureedge.net/providers/Microsoft.PackageManagement.NuGetProvider-2.8.5.208.dll' to ''.
At C:\Program Files\WindowsPowerShell\Modules\PowerShellGet\PSModule.psm1:6463 char:21
+             $null = PackageManagement\Install-PackageProvider -Name $script:NuGe ...

Calling a function within a Class method?

In order to have a "function within a function", if I understand what you're asking, you need PHP 5.3, where you can take advantage of the new Closure feature.

So you could have:

public function newTest() {
   $bigTest = function() {
        //Big Test Here
   }
}

What is the difference between functional and non-functional requirements?

Functional requirements

  1. Functional requirements specifies a function that a system or system component must be able to perform. It can be documented in various ways. The most common ones are written descriptions in documents, and use cases.

  2. Use cases can be textual enumeration lists as well as diagrams, describing user actions. Each use case illustrates behavioural scenarios through one or more functional requirements. Often, though, an analyst will begin by eliciting a set of use cases, from which the analyst can derive the functional requirements that must be implemented to allow a user to perform each use case.

  3. Functional requirements is what a system is supposed to accomplish. It may be

    • Calculations
    • Technical details
    • Data manipulation
    • Data processing
    • Other specific functionality
  4. A typical functional requirement will contain a unique name and number, a brief summary, and a rationale. This information is used to help the reader understand why the requirement is needed, and to track the requirement through the development of the system.

Non-functional requirements

LBushkin have already explained more about Non-functional requirements. I will add more.

  1. Non-functional requirements are any other requirement than functional requirements. This are the requirements that specifies criteria that can be used to judge the operation of a system, rather than specific behaviours.

  2. Non-functional requirements are in the form of "system shall be ", an overall property of the system as a whole or of a particular aspect and not a specific function. The system's overall properties commonly mark the difference between whether the development project has succeeded or failed.

  3. Non-functional requirements - can be divided into two main categories:

    • Execution qualities, such as security and usability, which are observable at run time.
    • Evolution qualities, such as testability, maintainability, extensibility and scalability, which are embodied in the static structure of the software system.
  4. Non-functional requirements place restrictions on the product being developed, the development process, and specify external constraints that the product must meet.
  5. The IEEE-Std 830 - 1993 lists 13 non-functional requirements to be included in a Software Requirements Document.
  1. Performance requirements
  2. Interface requirements
  3. Operational requirements
  4. Resource requirements
  5. Verification requirements
  6. Acceptance requirements
  7. Documentation requirements
  8. Security requirements
  9. Portability requirements
  10. Quality requirements
  11. Reliability requirements
  12. Maintainability requirements
  13. Safety requirements

Whether or not a requirement is expressed as a functional or a non-functional requirement may depend:

  • on the level of detail to be included in the requirements document
  • the degree of trust which exists between a system customer and a system developer.

Ex. A system may be required to present the user with a display of the number of records in a database. This is a functional requirement. How up-to-date [update] this number needs to be, is a non-functional requirement. If the number needs to be updated in real time, the system architects must ensure that the system is capable of updating the [displayed] record count within an acceptably short interval of the number of records changing.

References:

  1. Functional requirement
  2. Non-functional requirement
  3. Quantification and Traceability of Requirements

Hibernate JPA Sequence (non-Id)

Looking for answers to this problem, I stumbled upon this link

It seems that Hibernate/JPA isn't able to automatically create a value for your non-id-properties. The @GeneratedValue annotation is only used in conjunction with @Id to create auto-numbers.

The @GeneratedValue annotation just tells Hibernate that the database is generating this value itself.

The solution (or work-around) suggested in that forum is to create a separate entity with a generated Id, something like this:

@Entity
public class GeneralSequenceNumber {
  @Id
  @GeneratedValue(...)
  private Long number;
}

@Entity 
public class MyEntity {
  @Id ..
  private Long id;

  @OneToOne(...)
  private GeneralSequnceNumber myVal;
}

Difference between object and class in Scala

In scala, there is no static concept. So scala creates a singleton object to provide entry point for your program execution. If you don't create singleton object, your code will compile successfully but will not produce any output. Methods declared inside Singleton Object are accessible globally. A singleton object can extend classes and traits.

Scala Singleton Object Example

object Singleton{  
    def main(args:Array[String]){  
        SingletonObject.hello()         // No need to create object.  
    }  
}  


object SingletonObject{  
    def hello(){  
        println("Hello, This is Singleton Object")  
    }  
}  

Output:

Hello, This is Singleton Object

In scala, when you have a class with same name as singleton object, it is called companion class and the singleton object is called companion object.

The companion class and its companion object both must be defined in the same source file.

Scala Companion Object Example

class ComapanionClass{  
    def hello(){  
        println("Hello, this is Companion Class.")  
    }  
}  
object CompanoinObject{  
    def main(args:Array[String]){  
        new ComapanionClass().hello()  
        println("And this is Companion Object.")  
    }  
}  

Output:

Hello, this is Companion Class.
And this is Companion Object.

In scala, a class can contain:

1. Data member

2. Member method

3. Constructor Block

4. Nested class

5. Super class information etc.

You must initialize all instance variables in the class. There is no default scope. If you don't specify access scope, it is public. There must be an object in which main method is defined. It provides starting point for your program. Here, we have created an example of class.

Scala Sample Example of Class

class Student{  
    var id:Int = 0;                         // All fields must be initialized  
    var name:String = null;  
}  
object MainObject{  
    def main(args:Array[String]){  
        var s = new Student()               // Creating an object  
        println(s.id+" "+s.name);  
    }  
} 

I am sorry, I am too late but I hope it will help you.

How do I replace text in a selection?

1) Ctrl + F (or Cmd + F on a Mac);
2) Enter the string you want to find on the input at the bottom of the window.
3) Press "Find All";

All of the appearances are now selected. Do whatever you want.

Aside

There are a bunch of options at the left of the input that opens on Ctrl + F. There's one that says something like "Find in selected text". Select a bunch of text, check that option and repeat the same steps above starting from 2). Now, only matches belonging to that selection are selected.

Changing the color of a clicked table row using jQuery

jQuery :

$("#data td").toggle(function(){
    $(this).css('background-color','blue')
},function(){
    $(this).css('background-color','ur_default_color')
});

Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister

You are missing setter for salt property as indicated by the exception

Please add the setter as

 public void setSalt(long salt) {
      this.salt=salt;
 }

HttpListener Access Denied

If you use http://localhost:80/ as a prefix, you can listen to http requests with no need for Administrative privileges.

Page redirect with successful Ajax request

Another option is:

window.location.replace("your_url")

How to perform string interpolation in TypeScript?

Just use special `

var lyrics = 'Never gonna give you up';
var html = `<div>${lyrics}</div>`;

You can see more examples here.

Simplest way to do grouped barplot

There are several ways to do plots in R; lattice is one of them, and always a reasonable solution, +1 to @agstudy. If you want to do this in base graphics, you could try the following:

Reasonstats <- read.table(text="Category         Reason  Species
                                 Decline        Genuine       24
                                Improved        Genuine       16
                                Improved  Misclassified       85
                                 Decline  Misclassified       41
                                 Decline      Taxonomic        2
                                Improved      Taxonomic        7
                                 Decline        Unclear       41
                                Improved        Unclear      117", header=T)

ReasonstatsDec <- Reasonstats[which(Reasonstats$Category=="Decline"),]
ReasonstatsImp <- Reasonstats[which(Reasonstats$Category=="Improved"),]
Reasonstats3   <- cbind(ReasonstatsImp[,3], ReasonstatsDec[,3])
colnames(Reasonstats3) <- c("Improved", "Decline")
rownames(Reasonstats3) <- ReasonstatsImp$Reason

windows()
  barplot(t(Reasonstats3), beside=TRUE, ylab="number of species", 
          cex.names=0.8, las=2, ylim=c(0,120), col=c("darkblue","red"))
  box(bty="l")

enter image description here

Here's what I did: I created a matrix with two columns (because your data were in columns) where the columns were the species counts for Decline and for Improved. Then I made those categories the column names. I also made the Reasons the row names. The barplot() function can operate over this matrix, but wants the data in rows rather than columns, so I fed it a transposed version of the matrix. Lastly, I deleted some of your arguments to your barplot() function call that were no longer needed. In other words, the problem was that your data weren't set up the way barplot() wants for your intended output.

How do I wait for a promise to finish before returning the variable of a function?

Instead of returning a resultsArray you return a promise for a results array and then then that on the call site - this has the added benefit of the caller knowing the function is performing asynchronous I/O. Coding concurrency in JavaScript is based on that - you might want to read this question to get a broader idea:

function resultsByName(name)
{   
    var Card = Parse.Object.extend("Card");
    var query = new Parse.Query(Card);
    query.equalTo("name", name.toString());

    var resultsArray = [];

    return query.find({});                           

}

// later
resultsByName("Some Name").then(function(results){
    // access results here by chaining to the returned promise
});

You can see more examples of using parse promises with queries in Parse's own blog post about it.

TCPDF Save file to folder?

$pdf->Output( "myfile.pdf", "F");

TCPDF ERROR: Unable to create output file: myfile.pdf

In the include/tcpdf_static.php file about 2435 line in the static function fopenLocal if I delete the complete 'if statement' it works fine.

public static function fopenLocal($filename, $mode) {
    /*if (strpos($filename, '://') === false) {
        $filename = 'file://'.$filename;
    } elseif (strpos($filename, 'file://') !== 0) {
        return false;
    }*/
    return fopen($filename, $mode);
}

Argument Exception "Item with Same Key has already been added"

That Exception is thrown if there is already a key in the dictionary when you try to add the new one.

There must be more than one line in rct3Lines with the same first word. You can't have 2 entries in the same dictionary with the same key.

You need to decide what you want to happen if the key already exists - if you want to just update the value where the key exists you can simply

rct3Features[items[0]]=items[1]

but, if not you may want to test if the key already exists with:

if(rect3Features.ContainsKey(items[0]))
{
    //Do something
} 
else 
{
    //Do something else
}

How to get the latest record in each group using GROUP BY?

This is a standard problem.

Note that MySQL allows you to omit columns from the GROUP BY clause, which Standard SQL does not, but you do not get deterministic results in general when you use the MySQL facility.

SELECT *
  FROM Messages AS M
  JOIN (SELECT To_ID, From_ID, MAX(TimeStamp) AS Most_Recent
          FROM Messages
         WHERE To_ID = 12345678
         GROUP BY From_ID
       ) AS R
    ON R.To_ID = M.To_ID AND R.From_ID = M.From_ID AND R.Most_Recent = M.TimeStamp
 WHERE M.To_ID = 12345678

I've added a filter on the To_ID to match what you're likely to have. The query will work without it, but will return a lot more data in general. The condition should not need to be stated in both the nested query and the outer query (the optimizer should push the condition down automatically), but it can do no harm to repeat the condition as shown.

What's the difference between an element and a node in XML?

The Node object is the primary data type for the entire DOM.

A node can be an element node, an attribute node, a text node, or any other of the node types explained in the "Node types" chapter.

An XML element is everything from (including) the element's start tag to (including) the element's end tag.

How to create a timeline with LaTeX?

The tikz package seems to have what you want.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{snakes}

\begin{document}

  \begin{tikzpicture}[snake=zigzag, line before snake = 5mm, line after snake = 5mm]
    % draw horizontal line   
    \draw (0,0) -- (2,0);
    \draw[snake] (2,0) -- (4,0);
    \draw (4,0) -- (5,0);
    \draw[snake] (5,0) -- (7,0);

    % draw vertical lines
    \foreach \x in {0,1,2,4,5,7}
      \draw (\x cm,3pt) -- (\x cm,-3pt);

    % draw nodes
    \draw (0,0) node[below=3pt] {$ 0 $} node[above=3pt] {$   $};
    \draw (1,0) node[below=3pt] {$ 1 $} node[above=3pt] {$ 10 $};
    \draw (2,0) node[below=3pt] {$ 2 $} node[above=3pt] {$ 20 $};
    \draw (3,0) node[below=3pt] {$  $} node[above=3pt] {$  $};
    \draw (4,0) node[below=3pt] {$ 5 $} node[above=3pt] {$ 50 $};
    \draw (5,0) node[below=3pt] {$ 6 $} node[above=3pt] {$ 60 $};
    \draw (6,0) node[below=3pt] {$  $} node[above=3pt] {$  $};
    \draw (7,0) node[below=3pt] {$ n $} node[above=3pt] {$ 10n $};
  \end{tikzpicture}

\end{document}

I'm not too expert with tikz, but this does give a good timeline, which looks like:

enter image description here

Sorting JSON by values

jQuery.fn.sort = function() {  
    return this.pushStack( [].sort.apply( this, arguments ), []);  
};  

 function sortLastName(a,b){  
     if (a.l_name == b.l_name){
       return 0;
     }
     return a.l_name> b.l_name ? 1 : -1;  
 };  
  function sortLastNameDesc(a,b){  
     return sortLastName(a,b) * -1;  
 };
var people= [
{
"f_name": "john",
"l_name": "doe",
"sequence": "0",
"title" : "president",
"url" : "google.com",
"color" : "333333",
},
{
"f_name": "michael",
"l_name": "goodyear",
"sequence": "0",
"title" : "general manager",
"url" : "google.com",
"color" : "333333",
}]

sorted=$(people).sort(sortLastNameDesc);  

Reading PDF content with itextsharp dll in VB.NET or C#

Public Sub PDFTxtToPdf(ByVal sTxtfile As String, ByVal sPDFSourcefile As String)
        Dim sr As StreamReader = New StreamReader(sTxtfile)
    Dim doc As New Document()
    PdfWriter.GetInstance(doc, New FileStream(sPDFSourcefile, FileMode.Create))
    doc.Open()
    doc.Add(New Paragraph(sr.ReadToEnd()))
    doc.Close()
End Sub

Python 3 sort a dict by its values

To sort dictionary, we could make use of operator module. Here is the operator module documentation.

import operator                             #Importing operator module
dc =  {"aa": 3, "bb": 4, "cc": 2, "dd": 1}  #Dictionary to be sorted

dc_sort = sorted(dc.items(),key = operator.itemgetter(1),reverse = True)
print dc_sort

Output sequence will be a sorted list :

[('bb', 4), ('aa', 3), ('cc', 2), ('dd', 1)]

If we want to sort with respect to keys, we can make use of

dc_sort = sorted(dc.items(),key = operator.itemgetter(0),reverse = True)

Output sequence will be :

[('dd', 1), ('cc', 2), ('bb', 4), ('aa', 3)]

Facebook development in localhost

It's easy go to the app dashboard under the facebook login tab click settings then select Enforce HTTPs No, save settingsenter image description here

Java equivalent of unsigned long long?

I don't believe so. Once you want to go bigger than a signed long, I think BigInteger is the only (out of the box) way to go.

add column to mysql table if it does not exist

Just tried the stored procedure script. Seems the problem is the ' marks around the delimiters. The MySQL Docs show that delimiter characters do not need the single quotes.

So you want:

delimiter //

Instead of:

delimiter '//'

Works for me :)

How to get the class of the clicked element?

This should do the trick:

...
select: function(event, ui){ 
   ui.tab.attr('class');
} ,
...

For more info about the ui.tab see http://jqueryui.com/demos/tabs/#Events

How to align td elements in center

I personally didn't find any of these answers helpful. What worked in my case was giving the element float:none and position:relative. After that the element centered itself in the <td>.

Variable number of arguments in C++?

If you know the range of number of arguments that will be provided, you can always use some function overloading, like

f(int a)
    {int res=a; return res;}
f(int a, int b)
    {int res=a+b; return res;}

and so on...

Build an iOS app without owning a mac?

Most framework like React Native and Ionic allows you to built on their server. Meaning that they can help you compile and provide you with and .ipa file.

The problem is you need Xcode or Application loader to submit your app to Apple App Store Connect. Both of these are only available on OSX. To overcome this solution you have 2 options that I am aware of

  1. Rent mac virtually. http://www.macincloud.com
  2. Use website that helps you to upload your app (You need to have .ipa file). http://www.connectuploader.com

Can't create project on Netbeans 8.2

  1. Open notepad as administrator(right click on it then click run as administrator)
  2. Open the following document from Netbeans directory via Notepad file->open. Make sure where it was installed.

C:\Program Files\NetBeans 8.2\etc\netbeans.conf

  1. Add the following path;

netbeans_jdkhome="C:\Program Files\Java\jdk1.8.0_171"

  1. Save it as netbeans.conf in the same place.
  2. Now open the Netbeans.. Everything will work properly but you will be notified regarding jdk path in the beginning..

Use Font Awesome icon as CSS content

Update for Font Awesome 5 using SCSS

.icon {
  @extend %fa-icon;
  @extend .fas;

  &:before {
    content: fa-content($fa-var-user);
  }
}

How to make child element higher z-index than parent?

Nothing is impossible. Use the force.

.parent {
    position: relative;
}

.child {
    position: absolute;
    top:0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 100;
}

did you register the component correctly? For recursive components, make sure to provide the "name" option

In my case (quasar and command quasar dev for testing), I just forgot to restart dev Quasar command.

It seemed to me that components was automatically loaded when any change was done. But in this case, I reused component in another page and I got this message.

unix diff side-to-side results?

diff -y --suppress-common-lines file1 file2

What is the correct syntax for 'else if'?

Here is a little refactoring of your function (it does not use "else" or "elif"):

def function(a):
    if a not in (1, 2):
        a = 3
    print(str(a) + "a")

@ghostdog74: Python 3 requires parentheses for "print".

Why do I get the error "Unsafe code may only appear if compiling with /unsafe"?

Search your code for unsafe blocks or statements. These are only valid is compiled with /unsafe.

usr/bin/ld: cannot find -l<nameOfTheLibrary>

I had this problem with compiling LXC on a fresh VM with Centos 7.8. I tried all the above and failed. Some suggested removing the -static flag from the compiler configuration but I didn't want to change anything.

The only thing that helped was to install glibc-static and retry. Hope that helps someone.

How to order events bound with jQuery

I have same issue and found this topic. the above answers can solve those problem, but I don't think them are good plans.

let us think about the real world.

if we use those answers, we have to change our code. you have to change your code style. something like this:

original:

$('form').submit(handle);

hack:

bindAtTheStart($('form'),'submit',handle);

as time goes on, think about your project. the code is ugly and hard to read! anthoer reason is simple is always better. if you have 10 bindAtTheStart, it may no bugs. if you have 100 bindAtTheStart, are you really sure you can keep them in right order?

so if you have to bind same events multiple.I think the best way is control js-file or js-code load order. jquery can handle event data as queue. the order is first-in, first-out. you don't need change any code. just change load order.

Moment get current date

Just call moment as a function without any arguments:

moment()

For timezone information with moment, look at the moment-timezone package: http://momentjs.com/timezone/

Is there a null-coalescing (Elvis) operator or safe navigation operator in javascript?

Personally i use

function e(e,expr){try{return eval(expr);}catch(e){return null;}};

and for example safe get:

var a = e(obj,'e.x.y.z.searchedField');

How to write inside a DIV box with javascript

I would suggest Jquery:

$("#log").html("Type what you want to be shown to the user");   

How to disable logging on the standard error stream in Python?

I found a solution for this:

logger = logging.getLogger('my-logger')
logger.propagate = False
# now if you use logger it will not log to console.

This will prevent logging from being send to the upper logger that includes the console logging.

python: NameError:global name '...‘ is not defined

You need to call self.a() to invoke a from b. a is not a global function, it is a method on the class.

You may want to read through the Python tutorial on classes some more to get the finer details down.

How to set CATALINA_HOME variable in windows 7?

Here is tutorial how to do that (CATALINA_HOME is path to your Tomcat, so I suppose something like C:/Program Files/Tomcat/. And for starting server, you need to execute script startup.bat from command line, this will make it:)

How to fix a Div to top of page with CSS only

You can simply make the top div fixed:

#top { position: fixed; top: 20px; left: 20px; }

How do ports work with IPv6?

They work almost the same as today. However, be sure you include [] around your IP.

For example : http://[1fff:0:a88:85a3::ac1f]:8001/index.html

Wikipedia has a pretty good article about IPv6: http://en.wikipedia.org/wiki/IPv6#Addressing

How can I convert a series of images to a PDF from the command line on linux?

Using imagemagick, you can try:

convert page.png page.pdf

Or for multiple images:

convert page*.png mydoc.pdf

Printing tuple with string formatting in Python

For python 3

tup = (1,2,3)
print("this is a tuple %s" % str(tup))

javascript Unable to get property 'value' of undefined or null reference

The issue is how you're attempting to get the value. Things like...

if ( document.frm_new_user_request.u_isid.value == '' )

won't work. You need to find the element you want to get the value of first. It's not quite like a server side language where you can type in an object's reference name and a period to get or assign values.

document.getElementById('[id goes here]').value;

will work. Note: JavaScript is case-sensitive

I would recommend using:

var variablename = document.getElementById('[id goes here]');

or

var variablename = document.getElementById('[id goes here]').value;

How to set the java.library.path from Eclipse

You can add vm argument in your Eclipse.

Example :

-Djava.ext.dirs=cots_lib

where cots_lib is your external folder library.

Two div blocks on same line

Try an HTML table or use the following CSS :

<div id="bloc1" style="float:left">...</div>
<div id="bloc2">...</div>

(or use an HTML table)

Integer.toString(int i) vs String.valueOf(int i)

my openion is valueof() always called tostring() for representaion and so for rpresentaion of primtive type valueof is generalized.and java by default does not support Data type but it define its work with objaect and class its made all thing in cllas and made object .here Integer.toString(int i) create a limit that conversion for only integer.

How to replace all strings to numbers contained in each string in Notepad++?

I have Notepad++ v6.8.8

Find: [([a-zA-Z])]

Replace: [\'\1\']

Will produce: $array[XYZ] => $array['XYZ']

Edit existing excel workbooks and sheets with xlrd and xlwt

Here's another way of doing the code above using the openpyxl module that's compatible with xlsx. From what I've seen so far, it also keeps formatting.

from openpyxl import load_workbook
wb = load_workbook('names.xlsx')
ws = wb['SheetName']
ws['A1'] = 'A1'
wb.save('names.xlsx')

change background image in body

Just set an onload function on the body:

<body onload="init()">

Then do something like this in javascript:

function init() {
  var someimage = 'changableBackgroudImage';
  document.body.style.background = 'url(img/'+someimage+'.png) no-repeat center center'
}

You can change the 'someimage' variable to whatever you want depending on some conditions, such as the time of day or something, and that image will be set as the background image.

Create a list from two object lists with linq

There are a few pieces to doing this, assuming each list does not contain duplicates, Name is a unique identifier, and neither list is ordered.

First create an append extension method to get a single list:

static class Ext {
  public static IEnumerable<T> Append(this IEnumerable<T> source,
                                      IEnumerable<T> second) {
    foreach (T t in source) { yield return t; }
    foreach (T t in second) { yield return t; }
  }
}

Thus can get a single list:

var oneList = list1.Append(list2);

Then group on name

var grouped = oneList.Group(p => p.Name);

Then can process each group with a helper to process one group at a time

public Person MergePersonGroup(IGrouping<string, Person> pGroup) {
  var l = pGroup.ToList(); // Avoid multiple enumeration.
  var first = l.First();
  var result = new Person {
    Name = first.Name,
    Value = first.Value
  };
  if (l.Count() == 1) {
    return result;
  } else if (l.Count() == 2) {
    result.Change = first.Value - l.Last().Value;
    return result;
  } else {
    throw new ApplicationException("Too many " + result.Name);
  }
}

Which can be applied to each element of grouped:

var finalResult = grouped.Select(g => MergePersonGroup(g));

(Warning: untested.)

error, string or binary data would be truncated when trying to insert

Another situation, in which this error may occur is in SQL Server Management Studio. If you have "text" or "ntext" fields in your table, no matter what kind of field you are updating (for example bit or integer). Seems that the Studio does not load entire "ntext" fields and also updates ALL fields instead of the modified one. To solve the problem, exclude "text" or "ntext" fields from the query in Management Studio

Mocking Logger and LoggerFactory with PowerMock and Mockito

Use explicit injection. No other approach will allow you for instance to run tests in parallel in the same JVM.

Patterns that use anything classloader wide like static log binder or messing with environmental thinks like logback.XML are bust when it comes to testing.

Consider the parallelized tests I mention , or consider the case where you want to intercept logging of component A whose construction is hidden behind api B. This latter case is easy to deal with if you are using a dependency injected loggerfactory from the top, but not if you inject Logger as there no seam in this assembly at ILoggerFactory.getLogger.

And its not all about unit testing either. Sometimes we want integration tests to emit logging. Sometimes we don't. Someone's we want some of the integration testing logging to be selectively suppressed, eg for expected errors that would otherwise clutter the CI console and confuse. All easy if you inject ILoggerFactory from the top of your mainline (or whatever di framework you might use)

So...

Either inject a reporter as suggested or adopt a pattern of injecting the ILoggerFactory. By explicit ILoggerFactory injection rather than Logger you can support many access/intercept patterns and parallelization.

Get integer value of the current year in Java

The easiest way is to get the year from Calendar.

// year is stored as a static member
int year = Calendar.getInstance().get(Calendar.YEAR);

The entitlements specified...profile. (0xE8008016). Error iOS 4.2

i'm using xcode 6 and encounter this issue for one particular iphone 4

finally , i go to device => provision profile =>

and then add the profile manually and problem is fixed .

.map() a Javascript ES6 Map?

You can use this function:

function mapMap(map, fn) {
  return new Map(Array.from(map, ([key, value]) => [key, fn(value, key, map)]));
}

usage:

var map1 = new Map([["A", 2], ["B", 3], ["C", 4]]);

var map2 = mapMap(map1, v => v * v);

console.log(map1, map2);
/*
Map { A ? 2, B ? 3, C ? 4 }
Map { A ? 4, B ? 9, C ? 16 }
*/

Difference between signed / unsigned char

This because a char is stored at all effects as a 8-bit number. Speaking about a negative or positive char doesn't make sense if you consider it an ASCII code (which can be just signed*) but makes sense if you use that char to store a number, which could be in range 0-255 or in -128..127 according to the 2-complement representation.

*: it can be also unsigned, it actually depends on the implementation I think, in that case you will have access to extended ASCII charset provided by the encoding used

What is the connection string for localdb for version 11

I installed the mentioned .Net 4.0.2 update but I got the same error message saying:

A network-related or instance-specific error occurred while establishing a connection to SQL Server

I checked the SqlLocalDb via console as follows:

C:\>sqllocaldb create "Test"
LocalDB instance "Test" created with version 11.0.

C:\>sqllocaldb start "Test"
LocalDB instance "Test" started.

C:\>sqllocaldb info "Test"
Name:               Test
Version:            11.0.2100.60
Shared name:
Owner:              PC\TESTUSER
Auto-create:        No
State:              Running
Last start time:    05.09.2012 21:14:14
Instance pipe name: np:\\.\pipe\LOCALDB#B8A5271F\tsql\query

This means that SqlLocalDb is installed and running correctly. So what was the reason that I could not connect to SqlLocalDB via .Net code with this connectionstring: Server=(LocalDB)\v11.0;Integrated Security=true;?

Then I realized that my application was compiled for DotNet framework 3.5 but SqlLocalDb only works for DotNet 4.0.

After correcting this, the problem was solved.

How can I do DNS lookups in Python, including referring to /etc/hosts?

This code works well for returning all of the IP addresses that might belong to a particular URI. Since many systems are now in a hosted environment (AWS/Akamai/etc.), systems may return several IP addresses. The lambda was "borrowed" from @Peter Silva.

def get_ips_by_dns_lookup(target, port=None):
    '''
        this function takes the passed target and optional port and does a dns
        lookup. it returns the ips that it finds to the caller.

        :param target:  the URI that you'd like to get the ip address(es) for
        :type target:   string
        :param port:    which port do you want to do the lookup against?
        :type port:     integer
        :returns ips:   all of the discovered ips for the target
        :rtype ips:     list of strings

    '''
    import socket

    if not port:
        port = 443

    return list(map(lambda x: x[4][0], socket.getaddrinfo('{}.'.format(target),port,type=socket.SOCK_STREAM)))

ips = get_ips_by_dns_lookup(target='google.com')

Using Eloquent ORM in Laravel to perform search of database using LIKE

If you need to frequently use LIKE, you can simplify the problem a bit. A custom method like () can be created in the model that inherits the Eloquent ORM:

public  function scopeLike($query, $field, $value){
        return $query->where($field, 'LIKE', "%$value%");
}

So then you can use this method in such way:

User::like('name', 'Tomas')->get();

How to replace a character from a String in SQL?

UPDATE databaseName.tableName
SET columnName = replace(columnName, '?', '''')
WHERE columnName LIKE '%?%'

Xcode error - Thread 1: signal SIGABRT

SIGABRT is, as stated in other answers, a general uncaught exception. You should definitely learn a little bit more about Objective-C. The problem is probably in your UITableViewDelegate method didSelectRowAtIndexPath.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath

I can't tell you much more until you show us something of the code where you handle the table data source and delegate methods.

Saving a Excel File into .txt format without quotes

I see this question is already answered, but wanted to offer an alternative in case someone else finds this later.

Depending on the required delimiter, it is possible to do this without writing any code. The original question does not give details on the desired output type but here is an alternative:

PRN File Type

The easiest option is to save the file as a "Formatted Text (Space Delimited)" type. The VBA code line would look similar to this:

ActiveWorkbook.SaveAs FileName:=myFileName, FileFormat:=xlTextPrinter, CreateBackup:=False

In Excel 2007, this will annoyingly put a .prn file extension on the end of the filename, but it can be changed to .txt by renaming manually.

In Excel 2010, you can specify any file extension you want in the Save As dialog.

One important thing to note: the number of delimiters used in the text file is related to the width of the Excel column.

Observe:

Excel Screenshot

Becomes:

Text Screenshot

Is it possible to view RabbitMQ message contents directly from the command line?

If you want multiple messages from a queue, say 10 messages, the command to use is:

rabbitmqadmin get queue=<QueueName> ackmode=ack_requeue_true count=10

If you don't want the messages requeued, just change ackmode to ack_requeue_false.

When to use SELECT ... FOR UPDATE?

The only portable way to achieve consistency between rooms and tags and making sure rooms are never returned after they had been deleted is locking them with SELECT FOR UPDATE.

However in some systems locking is a side effect of concurrency control, and you achieve the same results without specifying FOR UPDATE explicitly.


To solve this problem, Thread 1 should SELECT id FROM rooms FOR UPDATE, thereby preventing Thread 2 from deleting from rooms until Thread 1 is done. Is that correct?

This depends on the concurrency control your database system is using.

  • MyISAM in MySQL (and several other old systems) does lock the whole table for the duration of a query.

  • In SQL Server, SELECT queries place shared locks on the records / pages / tables they have examined, while DML queries place update locks (which later get promoted to exclusive or demoted to shared locks). Exclusive locks are incompatible with shared locks, so either SELECT or DELETE query will lock until another session commits.

  • In databases which use MVCC (like Oracle, PostgreSQL, MySQL with InnoDB), a DML query creates a copy of the record (in one or another way) and generally readers do not block writers and vice versa. For these databases, a SELECT FOR UPDATE would come handy: it would lock either SELECT or the DELETE query until another session commits, just as SQL Server does.

When should one use REPEATABLE_READ transaction isolation versus READ_COMMITTED with SELECT ... FOR UPDATE?

Generally, REPEATABLE READ does not forbid phantom rows (rows that appeared or disappeared in another transaction, rather than being modified)

  • In Oracle and earlier PostgreSQL versions, REPEATABLE READ is actually a synonym for SERIALIZABLE. Basically, this means that the transaction does not see changes made after it has started. So in this setup, the last Thread 1 query will return the room as if it has never been deleted (which may or may not be what you wanted). If you don't want to show the rooms after they have been deleted, you should lock the rows with SELECT FOR UPDATE

  • In InnoDB, REPEATABLE READ and SERIALIZABLE are different things: readers in SERIALIZABLE mode set next-key locks on the records they evaluate, effectively preventing the concurrent DML on them. So you don't need a SELECT FOR UPDATE in serializable mode, but do need them in REPEATABLE READ or READ COMMITED.

Note that the standard on isolation modes does prescribe that you don't see certain quirks in your queries but does not define how (with locking or with MVCC or otherwise).

When I say "you don't need SELECT FOR UPDATE" I really should have added "because of side effects of certain database engine implementation".

Make a float only show two decimal places

It is not a matter of how the number is stored, it is a matter of how you are displaying it. When converting it to a string you must round to the desired precision, which in your case is two decimal places.

E.g.:

NSString* formattedNumber = [NSString stringWithFormat:@"%.02f", myFloat];

%.02f tells the formatter that you will be formatting a float (%f) and, that should be rounded to two places, and should be padded with 0s.

E.g.:

%f = 25.000000
%.f = 25
%.02f = 25.00

Why can't I check if a 'DateTime' is 'Nothing'?

In any programming language, be careful when using Nulls. The example above shows another issue. If you use a type of Nullable, that means that the variables instantiated from that type can hold the value System.DBNull.Value; not that it has changed the interpretation of setting the value to default using "= Nothing" or that the Object of the value can now support a null reference. Just a warning... happy coding!

You could create a separate class containing a value type. An object created from such a class would be a reference type, which could be assigned Nothing. An example:

Public Class DateTimeNullable
Private _value As DateTime

'properties
Public Property Value() As DateTime
    Get
        Return _value
    End Get
    Set(ByVal value As DateTime)
        _value = value
    End Set
End Property

'constructors
Public Sub New()
    Value = DateTime.MinValue
End Sub

Public Sub New(ByVal dt As DateTime)
    Value = dt
End Sub

'overridables
Public Overrides Function ToString() As String
    Return Value.ToString()
End Function

End Class

'in Main():

        Dim dtn As DateTimeNullable = Nothing
    Dim strTest1 As String = "Falied"
    Dim strTest2 As String = "Failed"
    If dtn Is Nothing Then strTest1 = "Succeeded"

    dtn = New DateTimeNullable(DateTime.Now)
    If dtn Is Nothing Then strTest2 = "Succeeded"

    Console.WriteLine("test1: " & strTest1)
    Console.WriteLine("test2: " & strTest2)
    Console.WriteLine(".ToString() = " & dtn.ToString())
    Console.WriteLine(".Value.ToString() = " & dtn.Value.ToString())

    Console.ReadKey()

    ' Output:
    'test1:  Succeeded()
    'test2:  Failed()
    '.ToString() = 4/10/2012 11:28:10 AM
    '.Value.ToString() = 4/10/2012 11:28:10 AM

Then you could pick and choose overridables to make it do what you need. Lot of work - but if you really need it, you can do it.

Eclipse: How to build an executable jar with external jar?

You can do this by writing a manifest for your jar. Have a look at the Class-Path header. Eclipse has an option for choosing your own manifest on export.

The alternative is to add the dependency to the classpath at the time you invoke the application:

win32: java.exe -cp app.jar;dependency.jar foo.MyMainClass
*nix:  java -cp app.jar:dependency.jar foo.MyMainClass

How to watch and compile all TypeScript sources?

Today I designed this Ant MacroDef for the same problem as yours :

    <!--
    Recursively read a source directory for TypeScript files, generate a compile list in the
    format needed by the TypeScript compiler adding every parameters it take.
-->
<macrodef name="TypeScriptCompileDir">

    <!-- required attribute -->
    <attribute name="src" />

    <!-- optional attributes -->
    <attribute name="out" default="" />
    <attribute name="module" default="" />
    <attribute name="comments" default="" />
    <attribute name="declarations" default="" />
    <attribute name="nolib" default="" />
    <attribute name="target" default="" />

    <sequential>

        <!-- local properties -->
        <local name="out.arg"/>
        <local name="module.arg"/>
        <local name="comments.arg"/>
        <local name="declarations.arg"/>
        <local name="nolib.arg"/>
        <local name="target.arg"/>
        <local name="typescript.file.list"/>
        <local name="tsc.compile.file"/>

        <property name="tsc.compile.file" value="@{src}compile.list" />

        <!-- Optional arguments are not written to compile file when attributes not set -->
        <condition property="out.arg" value="" else='--out "@{out}"'>
            <equals arg1="@{out}" arg2="" />
        </condition>

        <condition property="module.arg" value="" else="--module @{module}">
            <equals arg1="@{module}" arg2="" />
        </condition>

        <condition property="comments.arg" value="" else="--comments">
            <equals arg1="@{comments}" arg2="" />
        </condition>

        <condition property="declarations.arg" value="" else="--declarations">
            <equals arg1="@{declarations}" arg2="" />
        </condition>

        <condition property="nolib.arg" value="" else="--nolib">
            <equals arg1="@{nolib}" arg2="" />
        </condition>

        <!-- Could have been defaulted to ES3 but let the compiler uses its own default is quite better -->
        <condition property="target.arg" value="" else="--target @{target}">
            <equals arg1="@{target}" arg2="" />
        </condition>

        <!-- Recursively read TypeScript source directory and generate a compile list -->
        <pathconvert property="typescript.file.list" dirsep="\" pathsep="${line.separator}">

            <fileset dir="@{src}">
                <include name="**/*.ts" />
            </fileset>

            <!-- In case regexp doesn't work on your computer, comment <mapper /> and uncomment <regexpmapper /> -->
            <mapper type="regexp" from="^(.*)$" to='"\1"' />
            <!--regexpmapper from="^(.*)$" to='"\1"' /-->

        </pathconvert>


        <!-- Write to the file -->
        <echo message="Writing tsc command line arguments to : ${tsc.compile.file}" />
        <echo file="${tsc.compile.file}" message="${typescript.file.list}${line.separator}${out.arg}${line.separator}${module.arg}${line.separator}${comments.arg}${line.separator}${declarations.arg}${line.separator}${nolib.arg}${line.separator}${target.arg}" append="false" />

        <!-- Compile using the generated compile file -->
        <echo message="Calling ${typescript.compiler.path} with ${tsc.compile.file}" />
        <exec dir="@{src}" executable="${typescript.compiler.path}">
            <arg value="@${tsc.compile.file}"/>
        </exec>

        <!-- Finally delete the compile file -->
        <echo message="${tsc.compile.file} deleted" />
        <delete file="${tsc.compile.file}" />

    </sequential>

</macrodef>

Use it in your build file with :

    <!-- Compile a single JavaScript file in the bin dir for release -->
    <TypeScriptCompileDir
        src="${src-js.dir}"
        out="${release-file-path}"
        module="amd"
    />

It is used in the project PureMVC for TypeScript I'm working on at the time using Webstorm.

Limiting the number of characters in a string, and chopping off the rest

Use this to cut off the non needed characters:

String.substring(0, maxLength); 

Example:

String aString ="123456789";
String cutString = aString.substring(0, 4);
// Output is: "1234" 

To ensure you are not getting an IndexOutOfBoundsException when the input string is less than the expected length do the following instead:

int maxLength = (inputString.length() < MAX_CHAR)?inputString.length():MAX_CHAR;
inputString = inputString.substring(0, maxLength);

If you want your integers and doubles to have a certain length then I suggest you use NumberFormat to format your numbers instead of cutting off their string representation.

SQL Server: How to use UNION with two queries that BOTH have a WHERE clause?

select * from 
(
    select top 2 t1.ID, t1.ReceivedDate
    from Table t1
    where t1.Type = 'TYPE_1'
    order by t1.ReceivedDate de
) t1
union
select * from 
(
    select top 2 t2.ID
    from Table t2
    where t2.Type = 'TYPE_2'
    order by t2.ReceivedDate desc
) t2

or using CTE (SQL Server 2005+)

;with One as
(
    select top 2 t1.ID, t1.ReceivedDate
    from Table t1
    where t1.Type = 'TYPE_1'
    order by t1.ReceivedDate de
)
,Two as
(
    select top 2 t2.ID
    from Table t2
    where t2.Type = 'TYPE_2'
    order by t2.ReceivedDate desc
)
select * from One
union
select * from Two

How to use AND in IF Statement

Brief syntax lesson

Cells(Row, Column) identifies a cell. Row must be an integer between 1 and the maximum for version of Excel you are using. Column must be a identifier (for example: "A", "IV", "XFD") or a number (for example: 1, 256, 16384)

.Cells(Row, Column) identifies a cell within a sheet identified in a earlier With statement:

With ActiveSheet
  :
  .Cells(Row,Column)
  :
End With

If you omit the dot, Cells(Row,Column) is within the active worksheet. So wsh = ActiveWorkbook wsh.Range is not strictly necessary. However, I always use a With statement so I do not wonder which sheet I meant when I return to my code in six months time. So, I would write:

With ActiveSheet
  :
  .Range.  
  :
End With

Actually, I would not write the above unless I really did want the code to work on the active sheet. What if the user has the wrong sheet active when they started the macro. I would write:

With Sheets("xxxx")
  :
  .Range.  
  :
End With

because my code only works on sheet xxxx.

Cells(Row,Column) identifies a cell. Cells(Row,Column).xxxx identifies a property of the cell. Value is a property. Value is the default property so you can usually omit it and the compiler will know what you mean. But in certain situations the compiler can be confused so the advice to include the .Value is good.

Cells(Row,Column) like "*Miami*" will give True if the cell is "Miami", "South Miami", "Miami, North" or anything similar.

Cells(Row,Column).Value = "Miami" will give True if the cell is exactly equal to "Miami". "MIAMI" for example will give False. If you want to accept MIAMI, use the lower case function:

Lcase(Cells(Row,Column).Value) = "miami"  

My suggestions

Your sample code keeps changing as you try different suggestions which I find confusing. You were using Cells(Row,Column) <> "Miami" when I started typing this.

Use

If Cells(i, "A").Value like "*Miami*" And Cells(i, "D").Value like "*Florida*" Then
  Cells(i, "C").Value = "BA"

if you want to accept, for example, "South Miami" and "Miami, North".

Use

If Cells(i, "A").Value = "Miami" And Cells(i, "D").Value like "Florida" Then
  Cells(i, "C").Value = "BA"

if you want to accept, exactly, "Miami" and "Florida".

Use

If Lcase(Cells(i, "A").Value) = "miami" And _
   Lcase(Cells(i, "D").Value) = "florida" Then
  Cells(i, "C").Value = "BA"

if you don't care about case.

Call to getLayoutInflater() in places not in activity

LayoutInflater inflater = (LayoutInflater) context.getSystemService( Context.LAYOUT_INFLATER_SERVICE );

Use this instead!

Java Runtime.getRuntime(): getting output from executing a command line program

Also we can use streams for obtain command output:

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

        Runtime runtime = Runtime.getRuntime();
        String[] commands  = {"free", "-h"};
        Process process = runtime.exec(commands);

        BufferedReader lineReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
        lineReader.lines().forEach(System.out::println);

        BufferedReader errorReader = new BufferedReader(new InputStreamReader(process.getErrorStream()));
        errorReader.lines().forEach(System.out::println);
    }

extract date only from given timestamp in oracle sql

Use the function cast() to convert from timestamp to date

select to_char(cast(sysdate as date),'DD-MM-YYYY') from dual;

For more info of function cast oracle11g http://docs.oracle.com/cd/B28359_01/server.111/b28286/functions016.htm#SQLRF51256

angular 2 how to return data from subscribe

I have used this way lots time ...

_x000D_
_x000D_
@Component({_x000D_
   selector: "data",_x000D_
   template: "<h1>{{ getData() }}</h1>"_x000D_
})_x000D_
_x000D_
export class DataComponent{_x000D_
    this.http.get(path).subscribe({_x000D_
       DataComponent.setSubscribeData(res);_x000D_
    })_x000D_
}_x000D_
_x000D_
_x000D_
static subscribeData:any;_x000D_
static setSubscribeData(data):any{_x000D_
    DataComponent.subscribeData=data;_x000D_
    return data;_x000D_
}
_x000D_
_x000D_
_x000D_

use static keyword and save your time... here either you can use static variable or directly return object you want.... hope it will help you.. happy coding...

Eclipse 3.5 Unable to install plugins

I had a similar problem setting up eclipse in the office. I had set up the for HTTP, HTTPS and SOCKS in:

Window>pref>general>network connections

Clearing the proxy settings for SOCKS fixed the problem for me.

Server.Transfer Vs. Response.Redirect

Response.Redirect involves an extra round trip and updates the address bar.

Server.Transfer does not cause the address bar to change, the server responds to the request with content from another page

e.g.

Response.Redirect:-

  1. On the client the browser requests a page http://InitiallyRequestedPage.aspx
  2. On the server responds to the request with 302 passing the redirect address http://AnotherPage.aspx.
  3. On the client the browser makes a second request to the address http://AnotherPage.aspx.
  4. On the server responds with content from http://AnotherPage.aspx

Server.Transfer:-

  1. On the client browser requests a page http://InitiallyRequestedPage.aspx
  2. On the server Server.Transfer to http://AnotherPage.aspx
  3. On the server the response is made to the request for http://InitiallyRequestedPage.aspx passing back content from http://AnotherPage.aspx

Response.Redirect

Pros:- RESTful - It changes the address bar, the address can be used to record changes of state inbetween requests.

Cons:- Slow - There is an extra round-trip between the client and server. This can be expensive when there is substantial latency between the client and the server.

Server.Transfer

Pros:- Quick.

Cons:- State lost - If you're using Server.Transfer to change the state of the application in response to post backs, if the page is then reloaded that state will be lost, as the address bar will be the same as it was on the first request.

What does "pending" mean for request in Chrome Developer Window?

I also get this when using the HTTPS everywhere plugin. This plugin has a list of sites that also have https instead of http. So I assume before the actual request is made it is already being cancelled somehow.

So for example when I go to http://stackexchange.com, in Developer I first see a request with status (terminated). This request has some headers, but only the GET, User-Agent, and Accept. No response as well.

Then there is request to https://stackexchange.com with full headers etc.

So I assume it is used for requests that aren't sent.

Windows 7 environment variable not working in path

If there is any error at all in the PATH windows will silently disregard it. Things like having %PATH% or spaces between items in your path will break it. Be warned

Protect .NET code from reverse engineering?

Well, you cannot FULLY protect your product from being cracked, but you can maximize/enhance the security levels and make it a little bit too difficult to be cracked by newbies and intermediate crackers.

But bear in mind nothing is uncrackable, only the software on server side is well protected and cannot be cracked. Anyway, to enhance the security levels in your application, you can do some simple steps to prevent some crackers "not all" from cracking your applications. These steps will make these crackers go nuts and maybe desperate:

  • Obfuscate your source code, obviously this will make your source code look like a mess and unreadable.
  • Trigger several random checking routines inside your application like every two hours, 24 hours, one day, week, etc. or maybe after every action the user take.
  • Save your released application's MD5 checksum on your server and implement a routine that can check the current file MD5 checksum with the real one on you server side and make it randomly triggered. If the MD5 checksum has been changed that means this copy has been pirated. Now you can just block it or release an update to block it, etc.
  • Try to make a routine that can check if some of your codes (functions, classes, or specific routines) are actually have been modified or altered or even removed. I call it (code integrity check).
  • Use free unknown packers to pack your application. Or, if you have the money, go for commercial solutions such as Thamida or .NET Reactor. Those applications get updated regularly and once a cracker unpack your application, you can just get a new update from those companies and once you get the new update, you just pack your program and release a new update.
  • Release updates regularly and force your customer to download the latest update.
  • Finally make your application very cheap. Don't make it too expensive. Believe me, you will get more happy customers and crackers will just leave your application, because it isn't worth their time to crack a very cheap application.

Those are just simple methods to prevent newbies and intermediate crackers from cracking your application. If you have more ideas to protect your application just don't be shy to implement them. It will just make crackers lives hard, and they will get frustrated, and eventually they will leave your application, because it's just doesn't worth their time.

Lastly, you also need to consider spending your time on coding a good and quality applications. Don't waste your time on coding complicated security layers. If a good cracker wants to crack your application he/she will do no matter what you do...

Now go and implement some toys for the crackers...

I want to convert std::string into a const wchar_t *

You can use the ATL text conversion macros to convert a narrow (char) string to a wide (wchar_t) one. For example, to convert a std::string:

#include <atlconv.h>
...
std::string str = "Hello, world!";
CA2W pszWide(str.c_str());
loadU(pszWide);

You can also specify a code page, so if your std::string contains UTF-8 chars you can use:

CA2W pszWide(str.c_str(), CP_UTF8);

Very useful but Windows only.

Excel - find cell with same value in another worksheet and enter the value to the left of it

Assuming employee numbers are in the first column and their names are in the second:

=VLOOKUP(A1, Sheet2!A:B, 2,false)

How to remove/ignore :hover css style on touch devices

According to Jason´s answer we can address only devices that doesn't support hover with pure css media queries. We can also address only devices that support hover, like moogal´s answer in a similar question, with @media not all and (hover: none). It looks weird but it works.

I made a Sass mixin out of this for easier use:

@mixin hover-supported {
    @media not all and (hover: none) {
        &:hover {
            @content;
        }
    }
}

Update 2019-05-15: I recommend this article from Medium that goes through all different devices that we can target with CSS. Basically it's a mix of these media rules, combine them for specific targets:

@media (hover: hover) {
    /* Device that can hover (desktops) */
}
@media (hover: none) {
    /* Device that can not hover with ease */
}
@media (pointer: coarse) {
    /* Device with limited pointing accuracy (touch) */
}
@media (pointer: fine) {
    /* Device with accurate pointing (desktop, stylus-based) */
}
@media (pointer: none) {
    /* Device with no pointing */
}

Example for specific targets:

@media (hover: none) and (pointer: coarse) {
    /* Smartphones and touchscreens */
}

@media (hover: hover) and (pointer: fine) {
    /* Desktops with mouse */
}

I love mixins, this is how I use my hover mixin to only target devices that supports it:

@mixin on-hover {
    @media (hover: hover) and (pointer: fine) {
        &:hover {
            @content;
        }
    }
}

button {
    @include on-hover {
        color: blue;
    }
}

AngularJS Error: $injector:unpr Unknown Provider

Your angular module needs to be initialized properly. The global object app needs to be defined and initialized correctly to inject the service.

Please see below sample code for reference:

app.js

var app = angular.module('SampleApp',['ngRoute']); //You can inject the dependencies within the square bracket    

app.config(['$routeProvider', '$locationProvider', function($routeProvider, $locationProvider) {
  $routeProvider
    .when('/', {
      templateUrl:"partials/login.html",
      controller:"login"
    });

  $locationProvider
    .html5Mode(true);
}]);

app.factory('getSettings', ['$http', '$q', function($http, $q) {
  return {
    //Code edited to create a function as when you require service it returns object by default so you can't return function directly. That's what understand...
    getSetting: function (type) { 
      var q = $q.defer();
      $http.get('models/settings.json').success(function (data) {
        q.resolve(function() {
          var settings = jQuery.parseJSON(data);
          return settings[type];
        });
      });
      return q.promise;
    }
  }
}]);

app.controller("globalControl", ['$scope','getSettings', function ($scope,getSettings) {
  //Modified the function call for updated service
  var loadSettings = getSettings.getSetting('global');
  loadSettings.then(function(val) {
    $scope.settings = val;
  });
}]);

Sample HTML code should be like this:

<!DOCTYPE html>
<html>
    <head lang="en">
        <title>Sample Application</title>
    </head>
    <body ng-app="SampleApp" ng-controller="globalControl">
        <div>
            Your UI elements go here
        </div>
        <script src="app.js"></script>
    </body>
</html>

Please note that the controller is not binding to an HTML tag but to the body tag. Also, please try to include your custom scripts at end of the HTML page as this is a standard practice to follow for performance reasons.

I hope this will solve your basic injection issue.

Prevent row names to be written to file when using write.csv

For completeness, write_csv() from the readr package is faster and never writes row names

# install.packages('readr', dependencies = TRUE)
library(readr)
write_csv(t, "t.csv")

If you need to write big data out, use fwrite() from the data.table package. It's much faster than both write.csv and write_csv

# install.packages('data.table')
library(data.table)
fwrite(t, "t.csv")

Below is a benchmark that Edouard published on his site

microbenchmark(write.csv(data, "baseR_file.csv", row.names = F),
               write_csv(data, "readr_file.csv"),
               fwrite(data, "datatable_file.csv"),
               times = 10, unit = "s")

## Unit: seconds
##                                              expr        min         lq       mean     median         uq        max neval
##  write.csv(data, "baseR_file.csv", row.names = F) 13.8066424 13.8248250 13.9118324 13.8776993 13.9269675 14.3241311    10
##                 write_csv(data, "readr_file.csv")  3.6742610  3.7999409  3.8572456  3.8690681  3.8991995  4.0637453    10
##                fwrite(data, "datatable_file.csv")  0.3976728  0.4014872  0.4097876  0.4061506  0.4159007  0.4355469    10

How to read file with async/await properly?

To keep it succint and retain all functionality of fs:

const fs = require('fs');
const fsPromises = fs.promises;

async function loadMonoCounter() {
    const data = await fsPromises.readFile('monolitic.txt', 'binary');
    return new Buffer(data);
}

Importing fs and fs.promises separately will give access to the entire fs API while also keeping it more readable... So that something like the next example is easily accomplished.

// the 'next example'
fsPromises.access('monolitic.txt', fs.constants.R_OK | fs.constants.W_OK)
    .then(() => console.log('can access'))
    .catch(() => console.error('cannot access'));

How to declare and use 1D and 2D byte arrays in Verilog?

In addition to Marty's excellent Answer, the SystemVerilog specification offers the byte data type. The following declares a 4x8-bit variable (4 bytes), assigns each byte a value, then displays all values:

module tb;

byte b [4];

initial begin
    foreach (b[i]) b[i] = 1 << i;
    foreach (b[i]) $display("Address = %0d, Data = %b", i, b[i]);
    $finish;
end

endmodule

This prints out:

Address = 0, Data = 00000001
Address = 1, Data = 00000010
Address = 2, Data = 00000100
Address = 3, Data = 00001000

This is similar in concept to Marty's reg [7:0] a [0:3];. However, byte is a 2-state data type (0 and 1), but reg is 4-state (01xz). Using byte also requires your tool chain (simulator, synthesizer, etc.) to support this SystemVerilog syntax. Note also the more compact foreach (b[i]) loop syntax.

The SystemVerilog specification supports a wide variety of multi-dimensional array types. The LRM can explain them better than I can; refer to IEEE Std 1800-2005, chapter 5.

JQuery .on() method with multiple event handlers to one selector

If you want to use the same function on different events the following code block can be used

$('input').on('keyup blur focus', function () {
   //function block
})

How do I change a TCP socket to be non-blocking?

It is sometimes convenient to employ the "send/recv" family of system calls. If the flags parameter contains the MSG_DONTWAIT flag, each call will behave similar to a socket having the O_NONBLOCK flag set.

ssize_t send(int sockfd, const void *buf, size_t len, int flags);

ssize_t recv(int sockfd, void *buf, size_t len, int flags);

CSS list item width/height does not work

Declare the a element as display: inline-block and drop the width and height from the li element.

Alternatively, apply a float: left to the li element and use display: block on the a element. This is a bit more cross browser compatible, as display: inline-block is not supported in Firefox <= 2 for example.

The first method allows you to have a dynamically centered list if you give the ul element a width of 100% (so that it spans from left to right edge) and then apply text-align: center.

Use line-height to control the text's Y-position inside the element.

Passive Link in Angular 2 - <a href=""> equivalent

Here are some ways to do it:

  • <a href="" (click)="false">Click Me</a>

  • <a style="cursor: pointer;">Click Me</a>

  • <a href="javascript:void(0)">Click Me</a>

How to get certain commit from GitHub project

The easiest way that I found to recover a lost commit (that only exists on github and not locally) is to create a new branch that includes this commit.

  1. Have the commit open (url like: github.com/org/repo/commit/long-commit-sha)
  2. Click "Browse Files" on the top right
  3. Click the dropdown "Tree: short-sha..." on the top left
  4. Type in a new branch name
  5. git pull the new branch down to local

What is the difference between method overloading and overriding?

Method overloading deals with the notion of having two or more methods in the same class with the same name but different arguments.

void foo(int a)
void foo(int a, float b)

Method overriding means having two methods with the same arguments, but different implementations. One of them would exist in the parent class, while another will be in the derived, or child class. The @Override annotation, while not required, can be helpful to enforce proper overriding of a method at compile time.

class Parent {
    void foo(double d) {
        // do something
    }
}

class Child extends Parent {

    @Override
    void foo(double d){
        // this method is overridden.  
    }
}

What is the best way to create a string array in python?

The error message says it all: strs[sum-1] is a tuple, not a string. If you show more of your code someone will probably be able to help you. Without that we can only guess.

How to use responsive background image in css3 in bootstrap

Check this out,

body {
    background-color: black;
    background: url(img/bg.jpg) no-repeat center center fixed; 
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
}

Tensorflow image reading & display

You can use tf.keras API.

import tensorflow as tf
import numpy as np
from tensorflow.keras.preprocessing.image import load_img, array_to_img

tf.enable_eager_execution()

img = load_img("example.png")
img = tf.convert_to_tensor(np.asarray(img))
image = tf.image.resize_images(img, (800, 800))
to_img = array_to_img(image)
to_img.show()

Annotation @Transactional. How to rollback?

or programatically

TransactionAspectSupport.currentTransactionStatus().setRollbackOnly();

java.lang.ClassNotFoundException: org.springframework.boot.SpringApplication Maven

Another option is to use the Apache Maven Shade Plugin: This plugin provides the capability to package the artifact in an uber-jar, including its dependencies and to shade - i.e. rename - the packages of some of the dependencies.

add this to your build plugins section

<plugin>
     <groupId>org.apache.maven.plugins</groupId>
     <artifactId>maven-shade-plugin</artifactId>
</plugin>

When is each sorting algorithm used?

@dsimcha wrote: Counting sort: When you are sorting integers with a limited range

I would change that to:

Counting sort: When you sort positive integers (0 - Integer.MAX_VALUE-2 due to the pigeonhole).

You can always get the max and min values as an efficiency heuristic in linear time as well.
Also you need at least n extra space for the intermediate array and it is stable obviously.

/**
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;

(even though it actually will allow to MAX_VALUE-2) see: Do Java arrays have a maximum size?

Also I would explain that radix sort complexity is O(wn) for n keys which are integers of word size w. Sometimes w is presented as a constant, which would make radix sort better (for sufficiently large n) than the best comparison-based sorting algorithms, which all perform O(n log n) comparisons to sort n keys. However, in general w cannot be considered a constant: if all n keys are distinct, then w has to be at least log n for a random-access machine to be able to store them in memory, which gives at best a time complexity O(n log n). (from wikipedia)

How can I pass arguments to a batch file?

Here's how I did it:

@fake-command /u %1 /p %2

Here's what the command looks like:

test.cmd admin P@55w0rd > test-log.txt

The %1 applies to the first parameter the %2 (and here's the tricky part) applies to the second. You can have up to 9 parameters passed in this way.

Select statement to find duplicates on certain fields

try this query to have sepratley count of each SELECT statements :

select field1,count(field1) as field1Count,field2,count(field2) as field2Counts,field3, count(field3) as field3Counts
from table_name
group by field1,field2,field3
having count(*) > 1

Iterating over a numpy array

I think you're looking for the ndenumerate.

>>> a =numpy.array([[1,2],[3,4],[5,6]])
>>> for (x,y), value in numpy.ndenumerate(a):
...  print x,y
... 
0 0
0 1
1 0
1 1
2 0
2 1

Regarding the performance. It is a bit slower than a list comprehension.

X = np.zeros((100, 100, 100))

%timeit list([((i,j,k), X[i,j,k]) for i in range(X.shape[0]) for j in range(X.shape[1]) for k in range(X.shape[2])])
1 loop, best of 3: 376 ms per loop

%timeit list(np.ndenumerate(X))
1 loop, best of 3: 570 ms per loop

If you are worried about the performance you could optimise a bit further by looking at the implementation of ndenumerate, which does 2 things, converting to an array and looping. If you know you have an array, you can call the .coords attribute of the flat iterator.

a = X.flat
%timeit list([(a.coords, x) for x in a.flat])
1 loop, best of 3: 305 ms per loop

Is it possible to have SSL certificate for IP address, not domain name?

It entirely depends upon the Certificate Authority who issuing a certificate.

As far as Let's Encrypt CA, they wont issue TLS certificate on public IP address. https://community.letsencrypt.org/t/certificate-for-public-ip-without-domain-name/6082

To know your Certificate authority , you can execute following command and look for an entry marked below.

curl -v -u <username>:<password> "https://IPaddress/.."

enter image description here

How to view instagram profile picture in full-size?

You can even set the prof. pic size to its high resolution that is '1080x1080'

replace "150x150" with 1080x1080 and remove /vp/ from the link.

How to detect my browser version and operating system using JavaScript?

To detect operating system using JavaScript it is better to use navigator.userAgent instead of navigator.appVersion

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{_x000D_
  var OSName = "Unknown OS";_x000D_
  if (navigator.userAgent.indexOf("Win") != -1) OSName = "Windows";_x000D_
  if (navigator.userAgent.indexOf("Mac") != -1) OSName = "Macintosh";_x000D_
  if (navigator.userAgent.indexOf("Linux") != -1) OSName = "Linux";_x000D_
  if (navigator.userAgent.indexOf("Android") != -1) OSName = "Android";_x000D_
  if (navigator.userAgent.indexOf("like Mac") != -1) OSName = "iOS";_x000D_
  console.log('Your OS: ' + OSName);_x000D_
}
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