What is difference between @RequestBody and @RequestParam?
@RequestParam
makes Spring to map request parameters from the GET/POST request to your method argument.
GET Request
http://testwebaddress.com/getInformation.do?city=Sydney&country=Australia
public String getCountryFactors(@RequestParam(value = "city") String city,
@RequestParam(value = "country") String country){ }
POST Request
@RequestBody
makes Spring to map entire request to a model class and from there you can retrieve or set values from its getter and setter methods. Check below.
http://testwebaddress.com/getInformation.do
You have JSON
data as such coming from the front end and hits your controller class
{
"city": "Sydney",
"country": "Australia"
}
Java
Code - backend (@RequestBody
)
public String getCountryFactors(@RequestBody Country countryFacts)
{
countryFacts.getCity();
countryFacts.getCountry();
}
public class Country {
private String city;
private String country;
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
}
Spring MVC - Why not able to use @RequestBody and @RequestParam together
It's too late to answer this question, but it could help for new readers,
It seems version issues. I ran all these tests with spring 4.1.4 and found that the order of @RequestBody
and @RequestParam
doesn't matter.
- same as your result
- same as your result
- gave
body= "name=abc"
, and name = "abc"
- Same as 3.
body ="name=abc"
, name = "xyz,abc"
- same as 5.
What is difference between mutable and immutable String in java
In Java, all strings are immutable(Can't change). When you are trying to modify a String, what you are really doing is creating a new one.
Following ways we can create the string object
Using String literal
String str="java";
Using new keyword
String str = new String("java");
Using character array
char[] helloArray = { 'h', 'e', 'l', 'l', 'o', '.' };
String helloString = new String(helloArray);
coming to String immutability, simply means unmodifiable or unchangeable
Let's take one example
I'm initializing the value to the String literal s
String s="kumar";
Below I'm going to display the decimal representation of the location address using hashcode()
System.out.println(s.hashCode());
Simply printing the value of a String s
System.out.println("value "+s);
Okay, this time I'm inittializing value "kumar" to s1
String s1="kumar"; // what you think is this line, takes new location in the memory ???
Okay let's check by displaying hashcode of the s1 object which we created
System.out.println(s1.hashCode());
okay, let's check below code
String s2=new String("Kumar");
System.out.println(s2.hashCode()); // why this gives the different address ??
Okay, check this below code at last
String s3=new String("KUMAR");
System.out.println(s3.hashCode()); // again different address ???
YES, if you see Strings 's' and 's1' having the same hashcode because the value hold by 's' & 's1' are same that is 'kumar'
Let's consider String 's2' and 's3' these two Strings hashcode appears to be different in the sense, they both stored in a different location because you see their values are different.
since s and s1 hashcode is same because those values are same and storing in the same location.
Example 1:
Try below code and analyze line by line
public class StringImmutable {
public static void main(String[] args) {
String s="java";
System.out.println(s.hashCode());
String s1="javA";
System.out.println(s1.hashCode());
String s2=new String("Java");
System.out.println(s2.hashCode());
String s3=new String("JAVA");
System.out.println(s3.hashCode());
}
}
Example 2: Try below code and analyze line by line
public class StringImmutable {
public static void main(String[] args) {
String s="java";
s.concat(" programming"); // s can not be changed "immutablity"
System.out.println("value of s "+s);
System.out.println(" hashcode of s "+s.hashCode());
String s1="java";
String s2=s.concat(" programming"); // s1 can not be changed "immutablity" rather creates object s2
System.out.println("value of s1 "+s1);
System.out.println(" hashcode of s1 "+s1.hashCode());
System.out.println("value of s2 "+s2);
System.out.println(" hashcode of s2 "+s2.hashCode());
}
}
Okay, Let's look what is the difference between mutable and immutable.
mutable(it change) vs. immutable (it can't change)
public class StringMutableANDimmutable {
public static void main(String[] args) {
// it demonstrates immutable concept
String s="java";
s.concat(" programming"); // s can not be changed (immutablity)
System.out.println("value of s == "+s);
System.out.println(" hashcode of s == "+s.hashCode()+"\n\n");
// it demonstrates mutable concept
StringBuffer s1= new StringBuffer("java");
s1.append(" programming"); // s can be changed (mutablity)
System.out.println("value of s1 == "+s1);
System.out.println(" hashcode of s1 == "+s1.hashCode());
}
}
Any further questions?? please write on...
How to define Gradle's home in IDEA?
I had to setup the Project SDK before selecting gradle path. Once that was set correctly, I had to choose "Use default gradle wrapper (recommended) in "Import Project from Gradle" dialog.
Still works if I remove gradle using brew:
$ brew remove gradle
Closing Applications
for me best solotion this is
Thread.CurrentThread.Abort();
and force close app.
Can you center a Button in RelativeLayout?
It's really easy. Try the code below,
<RelativeLayout
android:id="@+id/second_RL"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@+id/first_RL"
android:background="@android:color/holo_blue_bright"
android:gravity="center">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
</RelativeLayout>
How can I subset rows in a data frame in R based on a vector of values?
This will give you what you want:
eg2011cleaned <- eg2011[!eg2011$ID %in% bg2011missingFromBeg, ]
The error in your second attempt is because you forgot the ,
In general, for convenience, the specification object[index]
subsets columns for a 2d object
. If you want to subset rows and keep all columns you have to use the specification
object[index_rows, index_columns]
, while index_cols
can be left blank, which will use all columns by default.
However, you still need to include the ,
to indicate that you want to get a subset of rows instead of a subset of columns.
Best practice for REST token-based authentication with JAX-RS and Jersey
This answer is all about authorization and it is a complement of my previous answer about authentication
Why another answer? I attempted to expand my previous answer by adding details on how to support JSR-250 annotations. However the original answer became the way too long and exceeded the maximum length of 30,000 characters. So I moved the whole authorization details to this answer, keeping the other answer focused on performing authentication and issuing tokens.
Supporting role-based authorization with the @Secured
annotation
Besides authentication flow shown in the other answer, role-based authorization can be supported in the REST endpoints.
Create an enumeration and define the roles according to your needs:
public enum Role {
ROLE_1,
ROLE_2,
ROLE_3
}
Change the @Secured
name binding annotation created before to support roles:
@NameBinding
@Retention(RUNTIME)
@Target({TYPE, METHOD})
public @interface Secured {
Role[] value() default {};
}
And then annotate the resource classes and methods with @Secured
to perform the authorization. The method annotations will override the class annotations:
@Path("/example")
@Secured({Role.ROLE_1})
public class ExampleResource {
@GET
@Path("{id}")
@Produces(MediaType.APPLICATION_JSON)
public Response myMethod(@PathParam("id") Long id) {
// This method is not annotated with @Secured
// But it's declared within a class annotated with @Secured({Role.ROLE_1})
// So it only can be executed by the users who have the ROLE_1 role
...
}
@DELETE
@Path("{id}")
@Produces(MediaType.APPLICATION_JSON)
@Secured({Role.ROLE_1, Role.ROLE_2})
public Response myOtherMethod(@PathParam("id") Long id) {
// This method is annotated with @Secured({Role.ROLE_1, Role.ROLE_2})
// The method annotation overrides the class annotation
// So it only can be executed by the users who have the ROLE_1 or ROLE_2 roles
...
}
}
Create a filter with the AUTHORIZATION
priority, which is executed after the AUTHENTICATION
priority filter defined previously.
The ResourceInfo
can be used to get the resource Method
and resource Class
that will handle the request and then extract the @Secured
annotations from them:
@Secured
@Provider
@Priority(Priorities.AUTHORIZATION)
public class AuthorizationFilter implements ContainerRequestFilter {
@Context
private ResourceInfo resourceInfo;
@Override
public void filter(ContainerRequestContext requestContext) throws IOException {
// Get the resource class which matches with the requested URL
// Extract the roles declared by it
Class<?> resourceClass = resourceInfo.getResourceClass();
List<Role> classRoles = extractRoles(resourceClass);
// Get the resource method which matches with the requested URL
// Extract the roles declared by it
Method resourceMethod = resourceInfo.getResourceMethod();
List<Role> methodRoles = extractRoles(resourceMethod);
try {
// Check if the user is allowed to execute the method
// The method annotations override the class annotations
if (methodRoles.isEmpty()) {
checkPermissions(classRoles);
} else {
checkPermissions(methodRoles);
}
} catch (Exception e) {
requestContext.abortWith(
Response.status(Response.Status.FORBIDDEN).build());
}
}
// Extract the roles from the annotated element
private List<Role> extractRoles(AnnotatedElement annotatedElement) {
if (annotatedElement == null) {
return new ArrayList<Role>();
} else {
Secured secured = annotatedElement.getAnnotation(Secured.class);
if (secured == null) {
return new ArrayList<Role>();
} else {
Role[] allowedRoles = secured.value();
return Arrays.asList(allowedRoles);
}
}
}
private void checkPermissions(List<Role> allowedRoles) throws Exception {
// Check if the user contains one of the allowed roles
// Throw an Exception if the user has not permission to execute the method
}
}
If the user has no permission to execute the operation, the request is aborted with a 403
(Forbidden).
To know the user who is performing the request, see my previous answer. You can get it from the SecurityContext
(which should be already set in the ContainerRequestContext
) or inject it using CDI, depending on the approach you go for.
If a @Secured
annotation has no roles declared, you can assume all authenticated users can access that endpoint, disregarding the roles the users have.
Supporting role-based authorization with JSR-250 annotations
Alternatively to defining the roles in the @Secured
annotation as shown above, you could consider JSR-250 annotations such as @RolesAllowed
, @PermitAll
and @DenyAll
.
JAX-RS doesn't support such annotations out-of-the-box, but it could be achieved with a filter. Here are a few considerations to keep in mind if you want to support all of them:
So an authorization filter that checks JSR-250 annotations could be like:
@Provider
@Priority(Priorities.AUTHORIZATION)
public class AuthorizationFilter implements ContainerRequestFilter {
@Context
private ResourceInfo resourceInfo;
@Override
public void filter(ContainerRequestContext requestContext) throws IOException {
Method method = resourceInfo.getResourceMethod();
// @DenyAll on the method takes precedence over @RolesAllowed and @PermitAll
if (method.isAnnotationPresent(DenyAll.class)) {
refuseRequest();
}
// @RolesAllowed on the method takes precedence over @PermitAll
RolesAllowed rolesAllowed = method.getAnnotation(RolesAllowed.class);
if (rolesAllowed != null) {
performAuthorization(rolesAllowed.value(), requestContext);
return;
}
// @PermitAll on the method takes precedence over @RolesAllowed on the class
if (method.isAnnotationPresent(PermitAll.class)) {
// Do nothing
return;
}
// @DenyAll can't be attached to classes
// @RolesAllowed on the class takes precedence over @PermitAll on the class
rolesAllowed =
resourceInfo.getResourceClass().getAnnotation(RolesAllowed.class);
if (rolesAllowed != null) {
performAuthorization(rolesAllowed.value(), requestContext);
}
// @PermitAll on the class
if (resourceInfo.getResourceClass().isAnnotationPresent(PermitAll.class)) {
// Do nothing
return;
}
// Authentication is required for non-annotated methods
if (!isAuthenticated(requestContext)) {
refuseRequest();
}
}
/**
* Perform authorization based on roles.
*
* @param rolesAllowed
* @param requestContext
*/
private void performAuthorization(String[] rolesAllowed,
ContainerRequestContext requestContext) {
if (rolesAllowed.length > 0 && !isAuthenticated(requestContext)) {
refuseRequest();
}
for (final String role : rolesAllowed) {
if (requestContext.getSecurityContext().isUserInRole(role)) {
return;
}
}
refuseRequest();
}
/**
* Check if the user is authenticated.
*
* @param requestContext
* @return
*/
private boolean isAuthenticated(final ContainerRequestContext requestContext) {
// Return true if the user is authenticated or false otherwise
// An implementation could be like:
// return requestContext.getSecurityContext().getUserPrincipal() != null;
}
/**
* Refuse the request.
*/
private void refuseRequest() {
throw new AccessDeniedException(
"You don't have permissions to perform this action.");
}
}
Note: The above implementation is based on the Jersey RolesAllowedDynamicFeature
. If you use Jersey, you don't need to write your own filter, just use the existing implementation.
How to use cookies in Python Requests
From the documentation:
get cookie from response
url = 'http://example.com/some/cookie/setting/url'
r = requests.get(url)
r.cookies
{'example_cookie_name': 'example_cookie_value'}
give cookie back to server on subsequent request
url = 'http://httpbin.org/cookies'
cookies = dict(cookies_are='working')
r = requests.get(url, cookies=cookies)`
How do I turn off the mysql password validation?
Further to the answer from ktbos:
I modified the mysqld.cnf file and mysql failed to start.
It turned out that I was modifying the wrong file!
So be sure the file you modify contains segment tags like [mysqld_safe] and [mysqld]. Under the latter I did as suggested and added the line:
validate_password_policy=LOW
This worked perfectly to resolve my issue of not requiring special characters within the password.
How to change the color of an image on hover
Ok, try this:
Get the image with the transparent circle - http://i39.tinypic.com/15s97vd.png
Put that image in a html element and change that element's background color via css. This way you get the logo with the circle in the color defined in the stylesheet.
The html
<div class="badassColorChangingLogo">
<img src="http://i39.tinypic.com/15s97vd.png" />
Or download the image and change the path to the downloaded image in your machine
</div>
The css
div.badassColorChangingLogo{
background-color:white;
}
div.badassColorChangingLogo:hover{
background-color:blue;
}
Keep in mind that this wont work on non-alpha capable browsers like ie6, and ie7. for ie you can use a js fix. Google ddbelated png fix and you can get the script.
How do I change an HTML selected option using JavaScript?
It's an old post, but if anyone is still looking for solution to this kind of problem, here is what I came up with:
<script>
document.addEventListener("DOMContentLoaded", function(e) {
document.forms['AddAndEdit'].elements['list'].value = 11;
});
</script>
Expand div to max width when float:left is set
And based on merkuro
's solution, if you would like maximize the one on the left, you should use:
<!DOCTYPE html>
<html lang="en">
<head>
<meta "charset="UTF-8" />
<title>Content with Menu</title>
<style>
.content .left {
margin-right: 100px;
background-color: green;
}
.content .right {
float: right;
width: 100px;
background-color: red;
}
</style>
</head>
<body>
<div class="content">
<div class="right">
<p>is</p>
<p>this</p>
<p>what</p>
<p>you are looking for?</p>
</div>
<div class="left">
<p>Hi, Flo!</p>
</div>
</div>
</body>
</html>
Has not been tested on IE, so it may look broken on IE.
Create a button with rounded border
For implementing the rounded border button with a border color use this
OutlineButton(
child: new Text("Button Text"),borderSide: BorderSide(color: Colors.blue),
onPressed: null,
shape: new RoundedRectangleBorder(borderRadius: new BorderRadius.circular(20.0))
),
What is the difference between smoke testing and sanity testing?
Smoke and sanity testing
In general, smoke and sanity testing seems very similar to many tester who have just started, because in both we talk about build, we talk about functionality and we talk about the rejection of builds, if build's health is not good for the feasible testing.
After going through several projects, from start ups to product base company, I figured out the basic difference between smoke and sanity testing.
I am writing difference between smoke testing and sanity testing here to help you in answering at least one question that normally all testers get asked in interview.
Smoke testing
Smoke testing is done to test the health of builds.
It is also known as the shallow and wide testing, in that we normally include those test cases which can cover all the functionality of the product.
We can say that it's the first step of testing and, after this, we normally do other kind of functional and system testing, including regression testing.
It's normally done by a developer with the help of certain scripts or certain tools, but in some cases it can be performed by a tester too.
It's valid for initial stage of a build confirmation. For example, suppose we have started the development of a certain product, and we are producing a build for the first time, then smoke testing becomes a necessity for the product.
Sanity testing
It is sub-regression
Sanity is done for those builds which have gone through many regression tests and a minor change in code has happened. In this case, we normally do the intensive testing of functionalities where this change has occurred or may have influenced.
- Due to this, it is also known as "narrow" and "deep" testing
It's performed by a tester
It's done for mature builds, like those that are just going to hit production, and have gone through multiple regression processes.
It can be removed from the testing process, if regression is already being performed.
If any build doesn't pass the sanity tests, then it is thrown to developer back for the correction of the build.
String Array object in Java
Your attempt at an athlete class seems to be dealing with a group of athletes, which is a design fault.
Define a class to represent a single athlete, with fields that represent the athlete's attributes:
public class Athlete {
private final String name;
private final String country;
private List<Performance> performances = new ArrayList<Performance>();
// other fields as required
public Athlete (String name, String country) {
this.name = name;
this.country = country;
}
// getters omitted
public List<Performance> getPerformances() {
return performances;
}
public Performance perform(Dive dive) {
// not sure what your intention is here, but something like this:
Performance p = new Performance(dive, this);
// add new performance to list
performances.add(p);
return p;
}
}
Then your main method would use ti like this:
public class Assignment1 {
public static void main(String[] args) {
String[] name = {"Art", "Dan", "Jen"};
String[] country = {"Canada", "Germant", "USA"};
Dive[] dive = new Dive[]{new Dive("somersault"), new Dive("foo"), new Dive("bar")};
for (int i = 0; i < name.length; i++) {
Athlete athlete = new Athlete(name[i], country[i]);
Performance performance = athlete.perform(dive[i]);
// do something with athlete and/or performance
}
}
}
'pip install' fails for every package ("Could not find a version that satisfies the requirement")
Upgrade pip as follows:
curl https://bootstrap.pypa.io/get-pip.py | python
Note: You may need to use sudo python
above if not in a virtual environment.
What's happening:
Python.org sites are stopping support for TLS versions 1.0 and 1.1. This means that Mac OS X version 10.12 (Sierra) or older will not be able to use pip unless they upgrade pip as above.
(Note that upgrading pip via pip install --upgrade pip
will also not upgrade it correctly. It is a chicken-and-egg issue)
This thread explains it (thanks to this Twitter post):
Mac users who use pip and PyPI:
If you are running macOS/OS X version 10.12 or older, then you ought
to upgrade to the latest pip (9.0.3) to connect to the Python Package
Index securely:
curl https://bootstrap.pypa.io/get-pip.py | python
and we recommend you do that by April 8th.
Pip 9.0.3 supports TLSv1.2 when running under system Python on macOS <
10.13. Official release notes: https://pip.pypa.io/en/stable/news/
Also, the Python status page:
Completed - The rolling brownouts are finished, and TLSv1.0 and TLSv1.1 have been disabled. Apr 11, 15:37 UTC
Update - The rolling brownouts have been upgraded to a blackout, TLSv1.0 and TLSv1.1 will be rejected with a HTTP 403 at all times.
Apr 8, 15:49 UTC
Lastly, to avoid other install errors, make sure you also upgrade setuptools after doing the above:
pip install --upgrade setuptools
Convert INT to VARCHAR SQL
Actually you don't need to use STR Or Convert. Just select 'xxx'+LTRIM(ColumnName) does the job.
Possibly, LTRIM uses Convert or STR under the hood.
LTRIM also removes need for providing length and usually default 10 is good enough for integer to string conversion.
SELECT LTRIM(ColumnName) FROM TableName
Passing $_POST values with cURL
$url='Your url'; // Specify your url
$data= array('parameterkey1'=>value,'parameterkey2'=>value); // Add parameters in key value
$ch = curl_init(); // Initialize cURL
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($data));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_exec($ch);
curl_close($ch);
What is a .NET developer?
Generally what's meant by that is a fairly intimate familiarity with one (or probably more) of the .NET languages (C#, VB.NET, etc.) and one (or less probably more) of the .NET stacks (WinForms, ASP.NET, WPF, etc.).
As for a specific "formal definition", I don't think you'll find one beyond that. The job description should be specific about what they're looking for. I wouldn't consider a job listing that asks for a ".NET developer" and provides no more detail than that to be sufficiently descriptive.
CSS: borders between table columns only
Edit 2
Erasmus has a better one-liner below
Not without tricky css selectors and extra markup and the like.
Something like this might do (using CSS selectors):
table {
border:none;
border-collapse: collapse;
}
table td {
border-left: 1px solid #000;
border-right: 1px solid #000;
}
table td:first-child {
border-left: none;
}
table td:last-child {
border-right: none;
}
Edit
To clarify @jeroen's comment blow, all you'd really need is:
table { border: none; border-collapse: collapse; }
table td { border-left: 1px solid #000; }
table td:first-child { border-left: none; }
Make div scrollable
I know this is an older question and that the original question needed the div
to have a fixed height
, but I thought I would share that this can also be accomplished without a fixed pixel height
for those looking for that kind of answer.
What I mean is that you can use something like:
.itemconfiguration
{
// ...style rules...
height: 25%; //or whatever percentage is needed
overflow-y: scroll;
// ...maybe more style rules...
}
This method works better for fluid layouts that need to adapt to the height of the screen they are being viewed on and also works for the overflow-x
property.
I also thought it would be worth mentioning the differences in the values for the overflow
style property as I've seen some people using auto
and others using scroll
:
visible = The overflowing content is not clipped and will make the div
larger than the set height
.
hidden = The overflowing content is clipped, and the rest of the content that is outside the set height
of the div
will be invisible
scroll = The overflowing content is clipped, but a scroll-bar is added to see the rest of the content within the set height
of the div
auto = If there is overflowing content, it is clipped and a scroll-bar should be added to see the rest of the content within the set height
of the div
How can I create a simple message box in Python?
Also you can position the other window before withdrawing it so that you position your message
#!/usr/bin/env python
from Tkinter import *
import tkMessageBox
window = Tk()
window.wm_withdraw()
#message at x:200,y:200
window.geometry("1x1+200+200")#remember its .geometry("WidthxHeight(+or-)X(+or-)Y")
tkMessageBox.showerror(title="error",message="Error Message",parent=window)
#centre screen message
window.geometry("1x1+"+str(window.winfo_screenwidth()/2)+"+"+str(window.winfo_screenheight()/2))
tkMessageBox.showinfo(title="Greetings", message="Hello World!")
How do I add a library project to Android Studio?
This is how it works for me in Android Studio 1.5+
In the project where you want to add external library project,
go to menu File -> New -> *Import new Module**, navigate to the library project which you want to add to your project, select to add 'library' module in your project. You will get settings.gradle in your projects, beside app, included library, something like this:
include ':app', ':library'
Add in build.gradle(Module :app) in the dependencies section:
Compile project(':library')
Rebuild the project, and that's it.
*You can add as many libraries (modules) as you want. In that case in settings.gradle you will have:
include ':app', ':lib1', ':lib2', ...
And in build.gradle, you'll need to have:
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
// Some other dependencies...
compile project(':lib1')
compile project(':lib2')
...
}
Javascript array declaration: new Array(), new Array(3), ['a', 'b', 'c'] create arrays that behave differently
Arrays in JS have two types of properties:
Regular elements and associative properties (which are nothing but objects)
When you define a = new Array()
, you are defining an empty array. Note that there are no associative objects yet
When you define b = new Array(2)
, you are defining an array with two undefined locations.
In both your examples of 'a' and 'b', you are adding associative properties i.e. objects to these arrays.
console.log (a)
or console.log(b)
prints the array elements i.e. []
and [undefined, undefined]
respectively. But since a1/a2
and b1/b2
are associative objects inside their arrays, they can be logged only by console.log(a.a1, a.a2)
kind of syntax
How to print without newline or space?
In Python 3, you can use the sep=
and end=
parameters of the print
function:
To not add a newline to the end of the string:
print('.', end='')
To not add a space between all the function arguments you want to print:
print('a', 'b', 'c', sep='')
You can pass any string to either parameter, and you can use both parameters at the same time.
If you are having trouble with buffering, you can flush the output by adding flush=True
keyword argument:
print('.', end='', flush=True)
Python 2.6 and 2.7
From Python 2.6 you can either import the print
function from Python 3 using the __future__
module:
from __future__ import print_function
which allows you to use the Python 3 solution above.
However, note that the flush
keyword is not available in the version of the print
function imported from __future__
in Python 2; it only works in Python 3, more specifically 3.3 and later. In earlier versions you'll still need to flush manually with a call to sys.stdout.flush()
. You'll also have to rewrite all other print statements in the file where you do this import.
Or you can use sys.stdout.write()
import sys
sys.stdout.write('.')
You may also need to call
sys.stdout.flush()
to ensure stdout
is flushed immediately.
How do I update all my CPAN modules to their latest versions?
An alternative method to using upgrade
from the default CPAN shell is to use cpanminus
and cpan-outdated
.
These are so easy and nimble to use that I hardly ever go back to CPAN shell. To upgrade all of your modules in one go, the command is:
cpan-outdated -p | cpanm
I recommend you install cpanminus
like the docs describe:
curl -L https://cpanmin.us | perl - App::cpanminus
And then install cpan-outdated
along with all other CPAN modules using cpanm
:
cpanm App::cpanoutdated
BTW: If you are using perlbrew
then you will need to repeat this for every Perl you have installed under it.
You can find out more about cpanminus
and cpan-outdated
at the Github repos here:
NavigationBar bar, tint, and title text color in iOS 8
Swift 4.2 version of Albert's answer-
UINavigationBar.appearance().barTintColor = UIColor(red: 234.0/255.0, green: 46.0/255.0, blue: 73.0/255.0, alpha: 1.0)
UINavigationBar.appearance().tintColor = UIColor.white
UINavigationBar.appearance().titleTextAttributes = [.foregroundColor : UIColor.white]
What is the error "Every derived table must have its own alias" in MySQL?
I arrived here because I thought I should check in SO if there are adequate answers, after a syntax error that gave me this error, or if I could possibly post an answer myself.
OK, the answers here explain what this error is, so not much more to say, but nevertheless I will give my 2 cents using my words:
This error is caused by the fact that you basically generate a new table with your subquery for the FROM
command.
That's what a derived table
is, and as such, it needs to have an alias
(actually a name reference to it).
So given the following hypothetical query:
SELECT id, key1
FROM (
SELECT t1.ID id, t2.key1 key1, t2.key2 key2, t2.key3 key3
FROM table1 t1
LEFT JOIN table2 t2 ON t1.id = t2.id
WHERE t2.key3 = 'some-value'
) AS tt
So, at the end, the whole subquery inside the FROM
command will produce the table that is aliased as tt
and it will have the following columns id
, key1
, key2
, key3
.
So, then with the initial SELECT
from that table we finally select the id
and key1
from the tt
.
Phone validation regex
First test the length of the string to see if it is between 9 and 15.
Then use this regex to validate:
^\+?\d+(-\d+)*$
This is yet another variation of the normal* (special normal*)*
pattern, with normal
being \d
and special
being -
.
How can I upgrade NumPy?
Because you have multiple versions of NumPy installed.
Try pip uninstall numpy
and pip list | grep numpy
several times, until you see no output from pip list | grep numpy
.
Then pip install numpy
will get you the newest version of NumPy.
Error: Local workspace file ('angular.json') could not be found
I had the same problem and found that there was no package.json in my project (but only the package-lock.json). I then
- restored the package.json from source control
- uninstalled the global and local angular-cli versions (like the instruction says)
- followed the standard upgrade procedure
..and all worked out fine. Took a while to figure it out, but that did it for me.
@Transactional(propagation=Propagation.REQUIRED)
When the propagation setting is PROPAGATION_REQUIRED, a logical transaction scope is created for each method upon which the setting is applied. Each such logical transaction scope can determine rollback-only status individually, with an outer transaction scope being logically independent from the inner transaction scope. Of course, in case of standard PROPAGATION_REQUIRED behavior, all these scopes will be mapped to the same physical transaction. So a rollback-only marker set in the inner transaction scope does affect the outer transaction's chance to actually commit (as you would expect it to).
http://static.springsource.org/spring/docs/3.1.x/spring-framework-reference/html/transaction.html
How do I redirect to another webpage?
First write properly. You want to navigate within an application for another link from your application for another link. Here is the code:
window.location.href = "http://www.google.com";
And if you want to navigate pages within your application then I also have code, if you want.
Get most recent file in a directory on Linux
A note about reliability:
Since the newline character is as valid as any in a file name, any solution that relies on lines like the head
/tail
based ones are flawed.
With GNU ls
, another option is to use the --quoting-style=shell-always
option and a bash
array:
eval "files=($(ls -t --quoting-style=shell-always))"
((${#files[@]} > 0)) && printf '%s\n' "${files[0]}"
(add the -A
option to ls
if you also want to consider hidden files).
If you want to limit to regular files (disregard directories, fifos, devices, symlinks, sockets...), you'd need to resort to GNU find
.
With bash 4.4 or newer (for readarray -d
) and GNU coreutils 8.25 or newer (for cut -z
):
readarray -t -d '' files < <(
LC_ALL=C find . -maxdepth 1 -type f ! -name '.*' -printf '%T@/%f\0' |
sort -rzn | cut -zd/ -f2)
((${#files[@]} > 0)) && printf '%s\n' "${files[0]}"
Or recursively:
readarray -t -d '' files < <(
LC_ALL=C find . -name . -o -name '.*' -prune -o -type f -printf '%T@%p\0' |
sort -rzn | cut -zd/ -f2-)
Best here would be to use zsh
and its glob qualifiers instead of bash
to avoid all this hassle:
Newest regular file in the current directory:
printf '%s\n' *(.om[1])
Including hidden ones:
printf '%s\n' *(D.om[1])
Second newest:
printf '%s\n' *(.om[2])
Check file age after symlink resolution:
printf '%s\n' *(-.om[1])
Recursively:
printf '%s\n' **/*(.om[1])
Also, with the completion system (compinit
and co) enabled, Ctrl+Xm becomes a completer that expands to the newest file.
So:
vi Ctrl+Xm
Would make you edit the newest file (you also get a chance to see which it before you press Return).
vi Alt+2Ctrl+Xm
For the second-newest file.
vi *.cCtrl+Xm
for the newest c
file.
vi *(.)Ctrl+Xm
for the newest regular file (not directory, nor fifo/device...), and so on.
What is the best way to get the count/length/size of an iterator?
There is no more efficient way, if all you have is the iterator. And if the iterator can only be used once, then getting the count before you get the iterator's contents is ... problematic.
The solution is either to change your application so that it doesn't need the count, or to obtain the count by some other means. (For example, pass a Collection
rather than Iterator
...)
How can I view all historical changes to a file in SVN
The oddly named "blame" command does this. If you use Tortoise, it gives you a "from revision" dialog, then a file listing with a line by line indicator of Revision number and author next to it.
If you right click on the revision info, you can bring up a "Show log" dialog that gives full checkin information, along with other files that were part of the checkin.
Checking if a list of objects contains a property with a specific value
You can use the Enumerable.Where extension method:
var matches = myList.Where(p => p.Name == nameToExtract);
Returns an IEnumerable<SampleClass>
. Assuming you want a filtered List
, simply call .ToList()
on the above.
By the way, if I were writing the code above today, I'd do the equality check differently, given the complexities of Unicode string handling:
var matches = myList.Where(p => String.Equals(p.Name, nameToExtract, StringComparison.CurrentCulture));
See also
How can I know if a process is running?
Synchronous solution :
void DisplayProcessStatus(Process process)
{
process.Refresh(); // Important
if(process.HasExited)
{
Console.WriteLine("Exited.");
}
else
{
Console.WriteLine("Running.");
}
}
Asynchronous solution:
void RegisterProcessExit(Process process)
{
// NOTE there will be a race condition with the caller here
// how to fix it is left as an exercise
process.Exited += process_Exited;
}
static void process_Exited(object sender, EventArgs e)
{
Console.WriteLine("Process has exited.");
}
cURL equivalent in Node.js?
I had a problem sending POST data to cloud DB from IOT RaspberryPi, but after hours I managed to get it straight.
I used command prompt to do so.
sudo curl --URL http://<username>.cloudant.com/<database_name> --user <api_key>:<pass_key> -X POST -H "Content-Type:application/json" --data '{"id":"123","type":"987"}'
Command prompt will show the problems - wrong username/pass; bad request etc.
--URL database/server location (I used simple free Cloudant DB)
--user is the authentication part username:pass I entered through API pass
-X defines what command to call (PUT,GET,POST,DELETE)
-H content type - Cloudant is about document database, where JSON is used
--data content itself sorted as JSON
Oracle: How to find out if there is a transaction pending?
The easiest and most reliable solution is to try and start a transaction and see it if succeeds. If some code already started a transaction but has not yet issued any DML, then the V$TRANSACTION view won't show anything.
In this example below, I handle the exception to raise a user-defined application error. To defer to an existing exception handler, just do a SET TRANSACTION and then immediately COMMIT to undo it.
DECLARE
transaction_in_progress EXCEPTION;
PRAGMA EXCEPTION_INIT(transaction_in_progress, -1453);
BEGIN
SET TRANSACTION NAME 'CHECK_FOR_TRANSACTION_ALREADY_SET';
COMMIT; -- end transaction
EXCEPTION
WHEN transaction_in_progress THEN
RAISE_APPLICATION_ERROR(-20000,'Transaction is already in progress');
END;
/
Meaning of Open hashing and Closed hashing
The name open addressing refers to the fact that the location ("address") of the element is not determined by its hash value. (This method is also called closed hashing).
In separate chaining, each bucket is independent, and has some sort of ADT (list, binary search trees, etc) of entries with the same index.
In a good hash table, each bucket has zero or one entries, because we need operations of order O(1) for insert, search, etc.
This is a example of separate chaining using C++ with a simple hash function using mod operator (clearly, a bad hash function)
Install an apk file from command prompt?
Open Terminal in Android Studio
You might see
C:\Users\nikhil\AppData\Local\Android\Sdk\platform-tools>
copy and paste your apk which you want to install on above path inside platform-tools.
In my case app-qa-debug.apk I kept inside platform-tools folder.
install command
adb install app-qa-debug.apk
so in the terminal you could see something
C:\Users\nikhil\AppData\Local\Android\Sdk\platform-tools>adb install app-qa-debug.apk
post-installation you could get the message as
Performing Streamed
Install Success
Given URL is not allowed by the Application configuration Facebook application error
You need to add the URL to your app:
- Go to the app, you want for user login, on the Facebook Developers page
- Click on the settings tab
- Click add platform
- Select Website
- After selection it will ask for some details such as URL for your website which uses login with facebook feature, fill the form and submit it
That's all and you are done. Make sure that the app's URL is the same from where you're logging in.
Writing a VLOOKUP function in vba
Have you tried:
Dim result As String
Dim sheet As Worksheet
Set sheet = ActiveWorkbook.Sheets("Data")
result = Application.WorksheetFunction.VLookup(sheet.Range("AN2"), sheet.Range("AA9:AF20"), 5, False)
How to change identity column values programmatically?
First save all IDs and alter them programmatically to the values you wan't, then remove them from database and then insert them again using something similar:
use [Name.Database]
go
set identity_insert [Test] ON
insert into [dbo].[Test]
([Id])
VALUES
(2)
set identity_insert [Test] OFF
For bulk insert use:
use [Name.Database]
go
set identity_insert [Test] ON
BULK INSERT [Test]
FROM 'C:\Users\Oscar\file.csv'
WITH (FIELDTERMINATOR = ';',
ROWTERMINATOR = '\n',
KEEPIDENTITY)
set identity_insert [Test] OFF
Sample data from file.csv:
2;
3;
4;
5;
6;
If you don't set identity_insert
to off you will get the following error:
Cannot insert explicit value for identity column in table 'Test' when
IDENTITY_INSERT is set to OFF.
What is INSTALL_PARSE_FAILED_NO_CERTIFICATES error?
Recently I had this error while upgrading to Android Studio 4.0. The cause was that the project had V2 Signing Disabled in the signing configuration in build.gradle
.
The solution was to remove v2SigningEnabled false
or explicitly set it to true
, which is the default value.
android {
signingConfigs {
dev {
v2SigningEnabled true
}
}
}
How do I set the version information for an existing .exe, .dll?
There is this tool ChangeVersion [1]
List of features (from the website):
- command line interface
- support for .EXE, .DLL and .RES files
- update FileVersion and ProductVersion based on a version mask
- add/change/remove version key strings
- adjust file flags (debug, special, private etc)
- update project files ( .bdsproj | .bpr | .bpk | .dproj )
- add/change main application icon
- use ini file with configuration
- Windows Vista support (needs elevation)
- easy to integrate into a continuous build environment
Full Disclosure: I know the guy who wrote this tool, I used to work with him. But this also means that I know he makes quality software ;)
[1] the link is dead. There seems to be mirrored version at download.cnet.com.
How to calculate the number of occurrence of a given character in each row of a column of strings?
nchar(as.character(q.data$string)) -nchar( gsub("a", "", q.data$string))
[1] 2 1 0
Notice that I coerce the factor variable to character, before passing to nchar. The regex functions appear to do that internally.
Here's benchmark results (with a scaled up size of the test to 3000 rows)
q.data<-q.data[rep(1:NROW(q.data), 1000),]
str(q.data)
'data.frame': 3000 obs. of 3 variables:
$ number : int 1 2 3 1 2 3 1 2 3 1 ...
$ string : Factor w/ 3 levels "greatgreat","magic",..: 1 2 3 1 2 3 1 2 3 1 ...
$ number.of.a: int 2 1 0 2 1 0 2 1 0 2 ...
benchmark( Dason = { q.data$number.of.a <- str_count(as.character(q.data$string), "a") },
Tim = {resT <- sapply(as.character(q.data$string), function(x, letter = "a"){
sum(unlist(strsplit(x, split = "")) == letter) }) },
DWin = {resW <- nchar(as.character(q.data$string)) -nchar( gsub("a", "", q.data$string))},
Josh = {x <- sapply(regmatches(q.data$string, gregexpr("g",q.data$string )), length)}, replications=100)
#-----------------------
test replications elapsed relative user.self sys.self user.child sys.child
1 Dason 100 4.173 9.959427 2.985 1.204 0 0
3 DWin 100 0.419 1.000000 0.417 0.003 0 0
4 Josh 100 18.635 44.474940 17.883 0.827 0 0
2 Tim 100 3.705 8.842482 3.646 0.072 0 0
How to trigger Jenkins builds remotely and to pass parameters
To pass/use the variables, first create parameters in the configure section of Jenkins. Parameters that you use can be of type text, String, file, etc.
After creating them, use the variable reference in the fields you want to.
For example: I have configured/created two variables for Email-subject
and Email-recipentList
, and I have used their reference in the EMail-ext
plugin (attached screenshot).
Get full path of a file with FileUpload Control
Try
Server.MapPath(FileUpload1.FileName);
Edit: This answer describes how to get the path to a file on the server. It does not describe how to get the path to a file on the client, which is what the question asked. The answer to that question is "you can't", because modern browser will not tell you the path on the client, for security reasons.
Installing pip packages to $HOME folder
You can specify the -t
option (--target
) to specify the destination directory. See pip install --help
for detailed information. This is the command you need:
pip install -t path_to_your_home package-name
for example, for installing say mxnet, in my $HOME
directory, I type:
pip install -t /home/foivos/ mxnet
CASE statement in SQLite query
The syntax is wrong in this clause (and similar ones)
CASE lkey WHEN lkey > 5 THEN
lkey + 2
ELSE
lkey
END
It's either
CASE WHEN [condition] THEN [expression] ELSE [expression] END
or
CASE [expression] WHEN [value] THEN [expression] ELSE [expression] END
So in your case it would read:
CASE WHEN lkey > 5 THEN
lkey + 2
ELSE
lkey
END
Check out the documentation (The CASE expression):
http://www.sqlite.org/lang_expr.html
SQL Case Sensitive String Compare
You can also convert that attribute as case sensitive using this syntax :
ALTER TABLE Table1
ALTER COLUMN Column1 VARCHAR(200)
COLLATE SQL_Latin1_General_CP1_CS_AS
Now your search will be case sensitive.
If you want to make that column case insensitive again, then use
ALTER TABLE Table1
ALTER COLUMN Column1 VARCHAR(200)
COLLATE SQL_Latin1_General_CP1_CI_AS
Android SDK manager won't open
Alright, I had the same problem, and none of these answers worked for me (I'm running Windows 8). I tried running tools/android.bat
and noticed I got some errors there. I investigated further and it seems there is something wrong in the code that finds your Java path.
This is how you fix it:
- Open up
tools/android.bat
in your favorite text editor
Search for this piece of code:
set java_exe=
call lib\find_java.bat
if not defined java_exe goto :EOF
Replace it with this:
set java_exe=D:\Program Files\Java\jdk1.7.0_07\bin\java.exe
where the path is the path to your Java exe.
Run android.bat
(in my case I had to specify the path to java_exe
in step 3 with no quotes to make it work.)
Creating a BLOB from a Base64 string in JavaScript
For all copy-paste lovers out there like me, here is a cooked download function which works on Chrome, Firefox and Edge:
window.saveFile = function (bytesBase64, mimeType, fileName) {
var fileUrl = "data:" + mimeType + ";base64," + bytesBase64;
fetch(fileUrl)
.then(response => response.blob())
.then(blob => {
var link = window.document.createElement("a");
link.href = window.URL.createObjectURL(blob, { type: mimeType });
link.download = fileName;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
});
}
return value after a promise
The best way to do this would be to use the promise returning function as it is, like this
lookupValue(file).then(function(res) {
// Write the code which depends on the `res.val`, here
});
The function which invokes an asynchronous function cannot wait till the async function returns a value. Because, it just invokes the async function and executes the rest of the code in it. So, when an async function returns a value, it will not be received by the same function which invoked it.
So, the general idea is to write the code which depends on the return value of an async function, in the async function itself.
Transfer files to/from session I'm logged in with PuTTY
Transferring files with Putty (pscp/plink.exe)
The default putty installation provides multiple ways to transfer files.
Most likely putty
is on your default path, so you can directly call
putty
from the command prompt. If it doesnt, you may have to change your
environmental variables. See instructions here:
https://it.cornell.edu/managed-servers/transfer-files-using-putt
Steps
Open command prompt by typing cmd
To transfer folders from your Windows computer to another Windows computer
use (notice the -r
flag, which indicates that the files will be
transferred recursively, no need to zip them up):
pscp -r -i C:/Users/username/.ssh/id_rsa.ppk "C:/Program Files (x86)/Terminal PC" [email protected]:/"C:/Program Files (x86)/"
To transfer files from your Windows computer to another Windows computer
use:
pscp -i C:/Users/username/.ssh/id_rsa.ppk "C:/Program Files (x86)/Terminal PC" [email protected]:/"C:/Program Files (x86)/"
Sometimes, you may only have plink
installed. plink
can potentially
be used to transfer files, but its best restricted to simple text files. It
may have unknown behavior with binary files (https://superuser.com/questions/1289455/create-text-file-on-remote-machine-using-plink-putty-with-contents-of-windows-lo):
plink -i C:/Users/username/.ssh/id_rsa.ppk user@host <localfile "cat >hostfile"
To transfer files from a linux server to a Windows computer to a Linux
computer use
pscp -r -i C:/Users/username/.ssh/id_rsa.ppk "C:/Program Files (x86)/Terminal PC" [email protected]:/home/username
For all these to work, you need to have the proper public/private key. To
generate that for putty see: https://superuser.com/a/1285789/658319
Why does the html input with type "number" allow the letter 'e' to be entered in the field?
<input type="number" onkeydown="return FilterInput(event)" onpaste="handlePaste(event)" >
function FilterInput(event) {
var keyCode = ('which' in event) ? event.which : event.keyCode;
isNotWanted = (keyCode == 69 || keyCode == 101);
return !isNotWanted;
};
function handlePaste (e) {
var clipboardData, pastedData;
// Get pasted data via clipboard API
clipboardData = e.clipboardData || window.clipboardData;
pastedData = clipboardData.getData('Text').toUpperCase();
if(pastedData.indexOf('E')>-1) {
//alert('found an E');
e.stopPropagation();
e.preventDefault();
}
};
What does a "Cannot find symbol" or "Cannot resolve symbol" error mean?
If you're getting this error in the build somewhere else, while your IDE says everything is perfectly fine, then check that you are using the same Java versions in both places.
For example, Java 7 and Java 8 have different APIs, so calling a non-existent API in an older Java version would cause this error.
Disable single warning error
This question comes up as one of the top 3 hits for the Google search for "how to suppress -Wunused-result in c++", so I'm adding this answer here since I figured it out and want to help the next person.
In case your warning/error is -Wunused
(or one of its sub-errors) or -Wunused -Werror
only, the solution is to cast to void
:
For -Wunused
or one of its sub-errors only1, you can just cast it to void
to disable the warning. This should work for any compiler and any IDE for both C and C++.
1Note 1: see gcc documentation here, for example, for a list of these warnings: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html, then search for the phrase "All the above -Wunused options combined" and look there for the main -Wunused
warning and above it for its sub-warnings. The sub-warnings that -Wunused
contains include:
-Wunused-but-set-parameter
-Wunused-but-set-variable
-Wunused-function
-Wunused-label
-Wunused-local-typedefs
-Wunused-parameter
-Wno-unused-result
-Wunused-variable
-Wunused-const-variable
-Wunused-const-variable=n
-Wunused-value
-Wunused
= contains all of the above -Wunused
options combined
Example of casting to void
to suppress this warning:
// some "unused" variable you want to keep around
int some_var = 7;
// turn off `-Wunused` compiler warning for this one variable
// by casting it to void
(void)some_var; // <===== SOLUTION! ======
For C++, this also works on functions which return a variable marked with [[nodiscard]]
:
C++ attribute: nodiscard (since C++17)
If a function declared nodiscard or a function returning an enumeration or class declared nodiscard by value is called from a discarded-value expression other than a cast to void, the compiler is encouraged to issue a warning.
(Source: https://en.cppreference.com/w/cpp/language/attributes/nodiscard)
So, the solution is to cast the function call to void
, as this is actually casting the value returned by the function (which is marked with the [[nodiscard]]
attribute) to void
.
Example:
// Some class or struct marked with the C++ `[[nodiscard]]` attribute
class [[nodiscard]] MyNodiscardClass
{
public:
// fill in class details here
private:
// fill in class details here
};
// Some function which returns a variable previously marked with
// with the C++ `[[nodiscard]]` attribute
MyNodiscardClass MyFunc()
{
MyNodiscardClass myNodiscardClass;
return myNodiscardClass;
}
int main(int argc, char *argv[])
{
// THE COMPILER WILL COMPLAIN ABOUT THIS FUNCTION CALL
// IF YOU HAVE `-Wunused` turned on, since you are
// discarding a "nodiscard" return type by calling this
// function and not using its returned value!
MyFunc();
// This is ok, however, as casing the returned value to
// `void` suppresses this `-Wunused` warning!
(void)MyFunc(); // <===== SOLUTION! ======
}
Lastly, you can also use the C++17 [[maybe_unused]]
attribute: https://en.cppreference.com/w/cpp/language/attributes/maybe_unused.
How to solve static declaration follows non-static declaration in GCC C code?
From what the error message complains about, it sounds like you should rather try to fix the source code. The compiler complains about difference in declaration, similar to for instance
void foo(int i);
...
void foo(double d) {
...
}
and this is not valid C code, hence the compiler complains.
Maybe your problem is that there is no prototype available when the function is used the first time and the compiler implicitly creates one that will not be static. If so the solution is to add a prototype somewhere before it is first used.
Choosing the correct upper and lower HSV boundaries for color detection with`cv::inRange` (OpenCV)
Ok, find color in HSV
space is an old but common question. I made a hsv-colormap
to fast look up special color. Here it is:
The x-axis represents Hue
in [0,180), the y-axis1 represents Saturation
in [0,255], the y-axis2 represents S = 255
, while keep V = 255
.
To find a color, usually just look up for the range of H
and S
, and set v in range(20, 255).
To find the orange color, we look up for the map, and find the best range: H :[10, 25], S: [100, 255], and V: [20, 255]
. So the mask is cv2.inRange(hsv,(10, 100, 20), (25, 255, 255) )
Then we use the found range to look for the orange color, this is the result:
The method is simple but common to use:
#!/usr/bin/python3
# 2018.01.21 20:46:41 CST
import cv2
img = cv2.imread("test.jpg")
hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
mask = cv2.inRange(hsv,(10, 100, 20), (25, 255, 255) )
cv2.imshow("orange", mask);cv2.waitKey();cv2.destroyAllWindows()
Similar answers:
How to define a threshold value to detect only green colour objects in an image :Opencv
Choosing correct HSV values for OpenCV thresholding with InRangeS
Replace Line Breaks in a String C#
Don't forget that replace doesn't do the replacement in the string, but returns a new string with the characters replaced. The following will remove line breaks (not replace them). I'd use @Brian R. Bondy's method if replacing them with something else, perhaps wrapped as an extension method. Remember to check for null values first before calling Replace or the extension methods provided.
string line = ...
line = line.Replace( "\r", "").Replace( "\n", "" );
As extension methods:
public static class StringExtensions
{
public static string RemoveLineBreaks( this string lines )
{
return lines.Replace( "\r", "").Replace( "\n", "" );
}
public static string ReplaceLineBreaks( this string lines, string replacement )
{
return lines.Replace( "\r\n", replacement )
.Replace( "\r", replacement )
.Replace( "\n", replacement );
}
}
passing several arguments to FUN of lapply (and others *apply)
If you look up the help page, one of the arguments to lapply
is the mysterious ...
. When we look at the Arguments section of the help page, we find the following line:
...: optional arguments to ‘FUN’.
So all you have to do is include your other argument in the lapply
call as an argument, like so:
lapply(input, myfun, arg1=6)
and lapply
, recognizing that arg1
is not an argument it knows what to do with, will automatically pass it on to myfun
. All the other apply
functions can do the same thing.
An addendum: You can use ...
when you're writing your own functions, too. For example, say you write a function that calls plot
at some point, and you want to be able to change the plot parameters from your function call. You could include each parameter as an argument in your function, but that's annoying. Instead you can use ...
(as an argument to both your function and the call to plot within it), and have any argument that your function doesn't recognize be automatically passed on to plot
.
How to add a class with React.js?
you can also use pure js to accomplish this like the old ways with jquery
try this if you want a simple way
document.getElementById("myID").classList.add("show-example");
Can the :not() pseudo-class have multiple arguments?
I was having some trouble with this, and the "X:not():not()" method wasn't working for me.
I ended up resorting to this strategy:
INPUT {
/* styles */
}
INPUT[type="radio"], INPUT[type="checkbox"] {
/* styles that reset previous styles */
}
It's not nearly as fun, but it worked for me when :not() was being pugnacious. It's not ideal, but it's solid.
What is the inclusive range of float and double in Java?
Binary floating-point numbers have interesting precision characteristics, since the value is stored as a binary integer raised to a binary power. When dealing with sub-integer values (that is, values between 0 and 1), negative powers of two "round off" very differently than negative powers of ten.
For example, the number 0.1 can be represented by 1 x 10-1, but there is no combination of base-2 exponent and mantissa that can precisely represent 0.1 -- the closest you get is 0.10000000000000001.
So if you have an application where you are working with values like 0.1 or 0.01 a great deal, but where small (less than 0.000000000000001%) errors cannot be tolerated, then binary floating-point numbers are not for you.
Conversely, if powers of ten are not "special" to your application (powers of ten are important in currency calculations, but not in, say, most applications of physics), then you are actually better off using binary floating-point, since it's usually at least an order of magnitude faster, and it is much more memory efficient.
The article from the Python documentation on floating point issues and limitations does an excellent job of explaining this issue in an easy to understand form. Wikipedia also has a good article on floating point that explains the math behind the representation.
IE8 crashes when loading website - res://ieframe.dll/acr_error.htm
Error "res://ieframe.dll/acr_error.htm#"
In my case, cannot open some websites or after openned IE8 gave "cannot return to website error".
After some visits to MS help sites like this and followed all the instructioms with no avail I saw what seems to me a tip.
In one of the MS websites they say to delete old Java versions using "control panel" and "add remove programs".
I did just that but only saw one version of Java v.6u22. Then I got the idea of download the last version of Java from some days ago v.6u29 and voila... IE8 is working now and seems OK.
I'm writing this in the hope this can help others.
How to convert a JSON string to a Map<String, String> with Jackson JSON
The following works for me:
Map<String, String> propertyMap = getJsonAsMap(json);
where getJsonAsMap
is defined like so:
public HashMap<String, String> getJsonAsMap(String json)
{
try
{
ObjectMapper mapper = new ObjectMapper();
TypeReference<Map<String,String>> typeRef = new TypeReference<Map<String,String>>() {};
HashMap<String, String> result = mapper.readValue(json, typeRef);
return result;
}
catch (Exception e)
{
throw new RuntimeException("Couldnt parse json:" + json, e);
}
}
Note that this will fail if you have child objects in your json (because they're not a String
, they're another HashMap
), but will work if your json is a key value list of properties like so:
{
"client_id": "my super id",
"exp": 1481918304,
"iat": "1450382274",
"url": "http://www.example.com"
}
Overriding the java equals() method - not working?
In Java, the equals()
method that is inherited from Object
is:
public boolean equals(Object other);
In other words, the parameter must be of type Object
. This is called overriding; your method public boolean equals(Book other)
does what is called overloading to the equals()
method.
The ArrayList
uses overridden equals()
methods to compare contents (e.g. for its contains()
and equals()
methods), not overloaded ones. In most of your code, calling the one that didn't properly override Object
's equals was fine, but not compatible with ArrayList
.
So, not overriding the method correctly can cause problems.
I override equals the following everytime:
@Override
public boolean equals(Object other){
if (other == null) return false;
if (other == this) return true;
if (!(other instanceof MyClass)) return false;
MyClass otherMyClass = (MyClass)other;
...test other properties here...
}
The use of the @Override
annotation can help a ton with silly mistakes.
Use it whenever you think you are overriding a super class' or interface's method. That way, if you do it the wrong way, you will get a compile error.
Create a new object from type parameter in generic class
I know late but @TadasPa's answer can be adjusted a little by using
TCreator: new() => T
instead of
TCreator: { new (): T; }
so the result should look like this
class A {
}
class B<T> {
Prop: T;
constructor(TCreator: new() => T) {
this.Prop = new TCreator();
}
}
var test = new B<A>(A);
How to get a list of MySQL views?
Here's a way to find all the views in every database on your instance:
SELECT TABLE_SCHEMA, TABLE_NAME
FROM information_schema.tables
WHERE TABLE_TYPE LIKE 'VIEW';
SyntaxError: expected expression, got '<'
I had this same error when I migrated a Wordpress site to another server.
The URL in the header for my js scripts was still pointing to the old server and domain name.
Once I updated the domain name, the error went away.
JavaScript open in a new window, not tab
You shouldn't need to. Allow the user to have whatever preferences they want.
Firefox does that by default because opening a page in a new window is annoying and a page should never be allowed to do so if that is not what is desired by the user. (Firefox does allow you to open tabs in a new window if you set it that way).
get number of columns of a particular row in given excel using Java
There are two Things you can do
use
int noOfColumns = sh.getRow(0).getPhysicalNumberOfCells();
or
int noOfColumns = sh.getRow(0).getLastCellNum();
There is a fine difference between them
- Option 1 gives the no of columns which are actually filled with contents(If the 2nd column of 10 columns is not filled you will get 9)
- Option 2 just gives you the index of last column. Hence done 'getLastCellNum()'
How to remove origin from git repository
Fairly straightforward:
git remote rm origin
As for the filter-branch
question - just add --prune-empty
to your filter branch command and it'll remove any revision that doesn't actually contain any changes in your resulting repo:
git filter-branch --prune-empty --subdirectory-filter path/to/subtree HEAD
How can I display a messagebox in ASP.NET?
Alert message with redirect
Response.Write("<script language='javascript'>window.alert('Popup message ');window.location='webform.aspx';</script>");
Only alert message
Response.Write("<script language='javascript'>window.alert('Popup message ')</script>");
How to check if array element exists or not in javascript?
I had to wrap techfoobar's answer in a try
..catch
block, like so:
try {
if(typeof arrayName[index] == 'undefined') {
// does not exist
}
else {
// does exist
}
}
catch (error){ /* ignore */ }
...that's how it worked in chrome, anyway (otherwise, the code stopped with an error).
Correct way to remove plugin from Eclipse
Eclipse Photon user here, found it under the toolbar's Windows > Preferences > Install/Update > "Uninstall or update" link > Click stuff and hit the "Uninstall" button.
endforeach in loops?
It's just a different syntax. Instead of
foreach ($a as $v) {
# ...
}
You could write this:
foreach ($a as $v):
# ...
endforeach;
They will function exactly the same; it's just a matter of style. (Personally I have never seen anyone use the second form.)
Spring JDBC Template for calling Stored Procedures
There are a number of ways to call stored procedures in Spring.
If you use CallableStatementCreator
to declare parameters, you will be using Java's standard interface of CallableStatement
, i.e register out parameters and set them separately. Using SqlParameter
abstraction will make your code cleaner.
I recommend you looking at SimpleJdbcCall
. It may be used like this:
SimpleJdbcCall jdbcCall = new SimpleJdbcCall(jdbcTemplate)
.withSchemaName(schema)
.withCatalogName(package)
.withProcedureName(procedure)();
...
jdbcCall.addDeclaredParameter(new SqlParameter(paramName, OracleTypes.NUMBER));
...
jdbcCall.execute(callParams);
For simple procedures you may use jdbcTemplate
's update
method:
jdbcTemplate.update("call SOME_PROC (?, ?)", param1, param2);
Create Local SQL Server database
You need to install a so-called Instance of MSSQL server on your computer. That is, installing all the needed files and services and database files. By default, there should be no MSSQL Server installed on your machine, assuming that you use a desktop Windows (7,8,10...).
You can start off with Microsoft SQL Server Express, which is a 10GB-limited, free version of MSSQL. It also lacks some other features (Server Agents, AFAIR), but it's good for some experiments.
Download it from the Microsoft Website and go through the installer process by choosing New SQL Server stand-alone installation ..
after running the installer.
Click through the steps. For your scenario (it sounds like you mainly want to test some stuff), the default options should suffice.
Just give attention to the step Instance Configuration
. There you will set the name of your MSSQL Server Instance. Call it something unique/descriptive like MY_TEST_INSTANCE
or the like. Also, choose wisely the Instance root directory
. In it, the database files will be placed, so it should be on a drive that has enough space.
Click further through the wizard, and when it's finished, your MSSQL instance will be up and running. It will also run at every boot if you have chosen the default settings for the services.
As soon as it's running in the background, you can connect to it with Management Studio by connecting to .\MY_TEST_INSTANCE
, given that that's the name you chose for the instance.
Remove the last line from a file in Bash
awk 'NR>1{print buf}{buf = $0}'
Essentially, this code says the following:
For each line after the first, print the buffered line
for each line, reset the buffer
The buffer is lagged by one line, hence you end up printing lines 1 to n-1
Proper way of checking if row exists in table in PL/SQL block
Select 'YOU WILL SEE ME' as ANSWER from dual
where exists (select 1 from dual where 1 = 1);
Select 'YOU CAN NOT SEE ME' as ANSWER from dual
where exists (select 1 from dual where 1 = 0);
Select 'YOU WILL SEE ME, TOO' as ANSWER from dual
where not exists (select 1 from dual where 1 = 0);
file_put_contents: Failed to open stream, no such file or directory
I was also stuck on the same kind of problem and I followed the simple steps below.
Just get the exact url of the file to which you want to copy, for example:
http://www.test.com/test.txt (file to copy)
Then pass the exact absolute folder path with filename where you do want to write that file.
If you are on a Windows machine then
d:/xampp/htdocs/upload/test.txt
If you are on a Linux machine then
/var/www/html/upload/test.txt
You can get the document root with the PHP function $_SERVER['DOCUMENT_ROOT']
.
Count specific character occurrences in a string
' Trying to find the amount of "." in the text
' if txtName looks like "hi...hi" then intdots will = 3
Dim test As String = txtName.Text
Dim intdots As Integer = 0
For i = 1 To test.Length
Dim inta As Integer = 0 + 1
Dim stra As String = test.Substring(inta)
If stra = "." Then
intdots = intdots + 1
End If
Next
txttest.text = intdots
How do I POST a x-www-form-urlencoded request using Fetch?
You can use react-native-easy-app that is easier to send http request and formulate interception request.
import { XHttp } from 'react-native-easy-app';
* Synchronous request
const params = {name:'rufeng',age:20}
const response = await XHttp().url(url).param(params).formEncoded().execute('GET');
const {success, json, message, status} = response;
* Asynchronous requests
XHttp().url(url).param(params).formEncoded().get((success, json, message, status)=>{
if (success){
this.setState({content: JSON.stringify(json)});
} else {
showToast(msg);
}
});
How to display gpg key details without importing it?
You may also use --keyid-format
switch to show short or long key ID:
$ gpg2 -n --with-fingerprint --keyid-format=short --show-keys <filename>
which outputs like this (example from PostgreSQL CentOS repo key):
pub dsa1024/442DF0F8 2008-01-08 [SCA] ¦
Key fingerprint = 68C9 E2B9 1A37 D136 FE74 D176 1F16 D2E1 442D F0F8 ¦ honor-keyserver-url
uid PostgreSQL RPM Building Project <[email protected]> ¦ When using --refresh-keys, if the key in question has a preferred keyserver URL, then use that
sub elg2048/D43F1AF8 2008-01-08 [E]
python getoutput() equivalent in subprocess
To catch errors with subprocess.check_output()
, you can use CalledProcessError
. If you want to use the output as string, decode it from the bytecode.
# \return String of the output, stripped from whitespace at right side; or None on failure.
def runls():
import subprocess
try:
byteOutput = subprocess.check_output(['ls', '-a'], timeout=2)
return byteOutput.decode('UTF-8').rstrip()
except subprocess.CalledProcessError as e:
print("Error in ls -a:\n", e.output)
return None
How can I refresh a page with jQuery?
You can use JavaScript location.reload()
method.
This method accepts a boolean parameter. true
or false
. If the parameter is true
; the page always reloaded from the server. If it is false
; which is the default or with empty parameter browser reload the page from it's cache.
With true
parameter
<button type="button" onclick="location.reload(true);">Reload page</button>
With default
/ false
parameter
<button type="button" onclick="location.reload();">Reload page</button>
Using jquery
<button id="Reloadpage">Reload page</button>
<script type="text/javascript">
$('#Reloadpage').click(function() {
location.reload();
});
</script>
Android: why setVisibility(View.GONE); or setVisibility(View.INVISIBLE); do not work
In my case I found that simply clearing the animation on the view before setting the visibility to GONE
works.
dp2.clearAnimation();
dp2.setVisibility(View.GONE);
I had a similar issue where I toggle between two views, one of which must always start off as GONE
- But when I displayed the views again, it was displaying over the first view even if setVisibility(GONE)
was called. Clearing the animation before setting the view to GONE
worked.
How to use sed to extract substring
sed 's/[^"]*"\([^"]*\).*/\1/'
does the job.
explanation of the part inside ' '
- s - tells sed to substitute
- / - start of regex string to search for
- [^"]* - any character that is not ", any number of times. (matching parameter name=)
- " - just a ".
- ([^"]*) - anything inside () will be saved for reference to use later. The \ are there so the brackets are not considered as characters to search for. [^"]* means the same as above. (matching RemoteHost for example)
- .* - any character, any number of times. (matching " access="readWrite"> /parameter)
- / - end of the search regex, and start of the substitute string.
- \1 - reference to that string we found in the brackets above.
- / end of the substitute string.
basically s/search for this/replace with this/ but we're telling him to replace the whole line with just a piece of it we found earlier.
d3.select("#element") not working when code above the html element
<script>$(function(){var svg = d3.select("#chart").append("svg:svg");});</script>
<div id="chart"></div>
In other words, it's not happening because you can't query against something that doesn't exist yet-- so just do it after the page loads (here via jquery).
Btw, its recommended that you place your JS files before the close of your body tag.
New line in JavaScript alert box
you have to use double quotes to display special char like \n \t etc... in js alert box
for exemple in php script:
$string = 'Hello everybody \n this is an alert box';
echo "<script>alert(\"$string\")</script>";
But a second possible problem arrives when you want to display a string specified in double quoted.
see link text
If the string is enclosed in double-quotes ("), PHP will interpret more escape sequences for special characters
escape sequences \n is transformed as 0x0A ASCII Escaped character and this character is not displayed in the alert box. The solution consists in to escape this special sequence:
$s = "Hello everybody \\n this is an alert box";
echo "<script>alert(\"$string\")</script>";
if you don't know how the string is enclosed you have to transform special characters to their escape sequences
$patterns = array("/\\\\/", '/\n/', '/\r/', '/\t/', '/\v/', '/\f/');
$replacements = array('\\\\\\', '\n', '\r', '\t', '\v', '\f');
$string = preg_replace($patterns, $replacements, $string);
echo "<script>alert(\"$string\")</script>";
how to add value to a tuple?
I was going through some details related to tuple
and list
, and what I understood is:
- Tuples are
Heterogeneous
collection data type
- Tuple has Fixed length (per tuple type)
- Tuple are Always finite
So for appending new item to a tuple, need to cast it to list
, and do append()
operation on it, then again cast it back to tuple.
But personally what I felt about the Question is, if Tuples are supposed to be finite, fixed length items and if we are using those data types in our application logics then there should not be a scenario to appending new items OR updating an item value in it.
So instead of list of tuples it should be list of list itself, Am I right on this?
How to disable button in React.js
I have had a similar problem, turns out we don't need hooks to do these, we can make an conditional render and it will still work fine.
<Button
type="submit"
disabled={
name === "" || email === "" || password === "" ? true : false
}
fullWidth
variant="contained"
color="primary"
className={classes.submit}>
SignUP
</Button>
Load local images in React.js
If you want load image with a local relative URL
as you are doing. React project has a default public
folder. You should put your images
folder inside. It will work.
Change onClick attribute with javascript
The line onclick = writeLED(1,1)
means that you want to immediately execute the function writeLED(arg1, arg2) with arguments 1, 1 and assign the return value; you need to instead create a function that will execute with those arguments and assign that. The topmost answer gave one example - another is to use the bind() function like so:
var writeLEDWithSpecifiedArguments = writeLED.bind(this, 1,1);
document.getElementById('buttonLED'+id).onclick = writeLEDWithSpecifiedArguments;
Responsive design with media query : screen size?
Here is media queries for common device breakpoints.
/* Smartphones (portrait and landscape) ----------- */
@media only screen and (min-device-width : 320px) and (max-device-width : 480px) {
/* Styles */
}
/* Smartphones (landscape) ----------- */
@media only screen and (min-width : 321px) {
/* Styles */
}
/* Smartphones (portrait) ----------- */
@media only screen and (max-width : 320px) {
/* Styles */
}
/* iPads (portrait and landscape) ----------- */
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) {
/* Styles */
}
/* iPads (landscape) ----------- */
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : landscape) {
/* Styles */
}
/* iPads (portrait) ----------- */
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : portrait) {
/* Styles */
}
/**********
iPad 3
**********/
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : landscape) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */
}
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : portrait) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */
}
/* Desktops and laptops ----------- */
@media only screen and (min-width : 1224px) {
/* Styles */
}
/* Large screens ----------- */
@media only screen and (min-width : 1824px) {
/* Styles */
}
/* iPhone 4 ----------- */
@media only screen and (min-device-width : 320px) and (max-device-width : 480px) and (orientation : landscape) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */
}
@media only screen and (min-device-width : 320px) and (max-device-width : 480px) and (orientation : portrait) and (-webkit-min-device-pixel-ratio : 2) {
/* Styles */
}
Detect the Internet connection is offline?
My way.
<!-- the file named "tt.jpg" should exist in the same directory -->
<script>
function testConnection(callBack)
{
document.getElementsByTagName('body')[0].innerHTML +=
'<img id="testImage" style="display: none;" ' +
'src="tt.jpg?' + Math.random() + '" ' +
'onerror="testConnectionCallback(false);" ' +
'onload="testConnectionCallback(true);">';
testConnectionCallback = function(result){
callBack(result);
var element = document.getElementById('testImage');
element.parentNode.removeChild(element);
}
}
</script>
<!-- usage example -->
<script>
function myCallBack(result)
{
alert(result);
}
</script>
<a href=# onclick=testConnection(myCallBack);>Am I online?</a>
Pointers in Python?
Yes! there is a way to use a variable as a pointer in python!
I am sorry to say that many of answers were partially wrong. In principle every equal(=) assignation shares the memory address (check the id(obj) function), but in practice it is not such. There are variables whose equal("=") behaviour works in last term as a copy of memory space, mostly in simple objects (e.g. "int" object), and others in which not (e.g. "list","dict" objects).
Here is an example of pointer assignation
dict1 = {'first':'hello', 'second':'world'}
dict2 = dict1 # pointer assignation mechanism
dict2['first'] = 'bye'
dict1
>>> {'first':'bye', 'second':'world'}
Here is an example of copy assignation
a = 1
b = a # copy of memory mechanism. up to here id(a) == id(b)
b = 2 # new address generation. therefore without pointer behaviour
a
>>> 1
Pointer assignation is a pretty useful tool for aliasing without the waste of extra memory, in certain situations for performing comfy code,
class cls_X():
...
def method_1():
pd1 = self.obj_clsY.dict_vars_for_clsX['meth1'] # pointer dict 1: aliasing
pd1['var4'] = self.method2(pd1['var1'], pd1['var2'], pd1['var3'])
#enddef method_1
...
#endclass cls_X
but one have to be aware of this use in order to prevent code mistakes.
To conclude, by default some variables are barenames (simple objects like int, float, str,...), and some are pointers when assigned between them (e.g. dict1 = dict2). How to recognize them? just try this experiment with them. In IDEs with variable explorer panel usually appears to be the memory address ("@axbbbbbb...") in the definition of pointer-mechanism objects.
I suggest investigate in the topic. There are many people who know much more about this topic for sure. (see "ctypes" module). I hope it is helpful. Enjoy the good use of the objects! Regards, José Crespo
How do I use an INSERT statement's OUTPUT clause to get the identity value?
You can either have the newly inserted ID being output to the SSMS console like this:
INSERT INTO MyTable(Name, Address, PhoneNo)
OUTPUT INSERTED.ID
VALUES ('Yatrix', '1234 Address Stuff', '1112223333')
You can use this also from e.g. C#, when you need to get the ID back to your calling app - just execute the SQL query with .ExecuteScalar()
(instead of .ExecuteNonQuery()
) to read the resulting ID
back.
Or if you need to capture the newly inserted ID
inside T-SQL (e.g. for later further processing), you need to create a table variable:
DECLARE @OutputTbl TABLE (ID INT)
INSERT INTO MyTable(Name, Address, PhoneNo)
OUTPUT INSERTED.ID INTO @OutputTbl(ID)
VALUES ('Yatrix', '1234 Address Stuff', '1112223333')
This way, you can put multiple values into @OutputTbl
and do further processing on those. You could also use a "regular" temporary table (#temp
) or even a "real" persistent table as your "output target" here.
Insert Data Into Tables Linked by Foreign Key
You can do it in one sql statement for existing customers, 3 statements for new ones. All you have to do is be an optimist and act as though the customer already exists:
insert into "order" (customer_id, price) values \
((select customer_id from customer where name = 'John'), 12.34);
If the customer does not exist, you'll get an sql exception which text will be something like:
null value in column "customer_id" violates not-null constraint
(providing you made customer_id non-nullable, which I'm sure you did). When that exception occurs, insert the customer into the customer table and redo the insert into the order table:
insert into customer(name) values ('John');
insert into "order" (customer_id, price) values \
((select customer_id from customer where name = 'John'), 12.34);
Unless your business is growing at a rate that will make "where to put all the money" your only real problem, most of your inserts will be for existing customers. So, most of the time, the exception won't occur and you'll be done in one statement.
How to increase the Java stack size?
It is hard to give a sensible solution since you are keen to avoid all sane approaches. Refactoring one line of code is the senible solution.
Note: Using -Xss sets the stack size of every thread and is a very bad idea.
Another approach is byte code manipulation to change the code as follows;
public static long fact(int n) {
return n < 2 ? n : n > 127 ? 0 : n * fact(n - 1);
}
given every answer for n > 127 is 0. This avoid changing the source code.
How many significant digits do floats and doubles have in java?
float: 32 bits (4 bytes) where 23 bits are used for the mantissa (about 7 decimal digits). 8 bits are used for the exponent, so a float can “move” the decimal point to the right or to the left using those 8 bits. Doing so avoids storing lots of zeros in the mantissa as in 0.0000003 (3 × 10-7) or 3000000 (3 × 107). There is 1 bit used as the sign bit.
double: 64 bits (8 bytes) where 52 bits are used for the mantissa (about 16 decimal digits). 11 bits are used for the exponent and 1 bit is the sign bit.
Since we are using binary (only 0 and 1), one bit in the mantissa is implicitly 1 (both float and double use this trick) when the number is non-zero.
Also, since everything is in binary (mantissa and exponents) the conversions to decimal numbers are usually not exact. Numbers like 0.5, 0.25, 0.75, 0.125 are stored exactly, but 0.1 is not. As others have said, if you need to store cents precisely, do not use float or double, use int, long, BigInteger or BigDecimal.
Sources:
http://en.wikipedia.org/wiki/Floating_point#IEEE_754:_floating_point_in_modern_computers
http://en.wikipedia.org/wiki/Binary64
http://en.wikipedia.org/wiki/Binary32
How to use WPF Background Worker
using System;
using System.ComponentModel;
using System.Threading;
namespace BackGroundWorkerExample
{
class Program
{
private static BackgroundWorker backgroundWorker;
static void Main(string[] args)
{
backgroundWorker = new BackgroundWorker
{
WorkerReportsProgress = true,
WorkerSupportsCancellation = true
};
backgroundWorker.DoWork += backgroundWorker_DoWork;
//For the display of operation progress to UI.
backgroundWorker.ProgressChanged += backgroundWorker_ProgressChanged;
//After the completation of operation.
backgroundWorker.RunWorkerCompleted += backgroundWorker_RunWorkerCompleted;
backgroundWorker.RunWorkerAsync("Press Enter in the next 5 seconds to Cancel operation:");
Console.ReadLine();
if (backgroundWorker.IsBusy)
{
backgroundWorker.CancelAsync();
Console.ReadLine();
}
}
static void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
for (int i = 0; i < 200; i++)
{
if (backgroundWorker.CancellationPending)
{
e.Cancel = true;
return;
}
backgroundWorker.ReportProgress(i);
Thread.Sleep(1000);
e.Result = 1000;
}
}
static void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
Console.WriteLine("Completed" + e.ProgressPercentage + "%");
}
static void backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Cancelled)
{
Console.WriteLine("Operation Cancelled");
}
else if (e.Error != null)
{
Console.WriteLine("Error in Process :" + e.Error);
}
else
{
Console.WriteLine("Operation Completed :" + e.Result);
}
}
}
}
Also, referr the below link you will understand the concepts of Background
:
http://www.c-sharpcorner.com/UploadFile/1c8574/threads-in-wpf/
AngularJS resource promise
If you want to use asynchronous method you need to use callback function by $promise, here is example:
var Regions = $resource('mocks/regions.json');
$scope.regions = Regions.query();
$scope.regions.$promise.then(function (result) {
$scope.regions = result;
});
When should the xlsm or xlsb formats be used?
One could think that xlsb has only advantages over xlsm.
The fact that xlsm is XML-based and xlsb is binary is that when workbook corruption occurs, you have better chances to repair a xlsm than a xlsb.
Python Pandas - Find difference between two data frames
Accepted answer Method 1 will not work for data frames with NaNs inside, as pd.np.nan != pd.np.nan
. I am not sure if this is the best way, but it can be avoided by
df1[~df1.astype(str).apply(tuple, 1).isin(df2.astype(str).apply(tuple, 1))]
It's slower, because it needs to cast data to string, but thanks to this casting pd.np.nan == pd.np.nan
.
Let's go trough the code. First we cast values to string, and apply tuple
function to each row.
df1.astype(str).apply(tuple, 1)
df2.astype(str).apply(tuple, 1)
Thanks to that, we get pd.Series
object with list of tuples. Each tuple contains whole row from df1
/df2
.
Then we apply isin
method on df1
to check if each tuple "is in" df2
.
The result is pd.Series
with bool values. True if tuple from df1
is in df2
. In the end, we negate results with ~
sign, and applying filter on df1
. Long story short, we get only those rows from df1
that are not in df2
.
To make it more readable, we may write it as:
df1_str_tuples = df1.astype(str).apply(tuple, 1)
df2_str_tuples = df2.astype(str).apply(tuple, 1)
df1_values_in_df2_filter = df1_str_tuples.isin(df2_str_tuples)
df1_values_not_in_df2 = df1[~df1_values_in_df2_filter]
Importing a function from a class in another file?
It would really help if you'd include the code that's not working (from the 'other' file), but I suspect you could do what you want with a healthy dose of the 'eval' function.
For example:
def run():
print "this does nothing"
def chooser():
return "run"
def main():
'''works just like:
run()'''
eval(chooser())()
The chooser returns the name of the function to execute, eval then turns a string into actual code to be executed in-place, and the parentheses finish off the function call.
How to set MouseOver event/trigger for border in XAML?
Yes, this is confusing...
According to this blog post, it looks like this is an omission from WPF.
To make it work you need to use a style:
<Border Name="ClearButtonBorder" Grid.Column="1" CornerRadius="0,3,3,0">
<Border.Style>
<Style>
<Setter Property="Border.Background" Value="Blue"/>
<Style.Triggers>
<Trigger Property="Border.IsMouseOver" Value="True">
<Setter Property="Border.Background" Value="Green" />
</Trigger>
</Style.Triggers>
</Style>
</Border.Style>
<TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Text="X" />
</Border>
I guess this problem isn't that common as most people tend to factor out this sort of thing into a style, so it can be used on multiple controls.
Is there a unique Android device ID?
I have came across this question several years ago, and have learn to implement a generalized solution based on various answers.
I have used the generalized solution for several years, in a real-world product. It serves me quite well so far. Here's the code snippet, based on various provided answers.
Note, getEmail
will return null most of the time, as we didn't ask for permission explicitly.
private static UniqueId getUniqueId() {
MyApplication app = MyApplication.instance();
// Our prefered method of obtaining unique id in the following order.
// (1) Advertising id
// (2) Email
// (2) ANDROID_ID
// (3) Instance ID - new id value, when reinstall the app.
////////////////////////////////////////////////////////////////////////////////////////////
// ADVERTISING ID
////////////////////////////////////////////////////////////////////////////////////////////
AdvertisingIdClient.Info adInfo = null;
try {
adInfo = AdvertisingIdClient.getAdvertisingIdInfo(app);
} catch (IOException e) {
Log.e(TAG, "", e);
} catch (GooglePlayServicesNotAvailableException e) {
Log.e(TAG, "", e);
} catch (GooglePlayServicesRepairableException e) {
Log.e(TAG, "", e);
}
if (adInfo != null) {
String aid = adInfo.getId();
if (!Utils.isNullOrEmpty(aid)) {
return UniqueId.newInstance(aid, UniqueId.Type.aid);
}
}
////////////////////////////////////////////////////////////////////////////////////////////
// EMAIL
////////////////////////////////////////////////////////////////////////////////////////////
final String email = Utils.getEmail();
if (!Utils.isNullOrEmpty(email)) {
return UniqueId.newInstance(email, UniqueId.Type.eid);
}
////////////////////////////////////////////////////////////////////////////////////////////
// ANDROID ID
////////////////////////////////////////////////////////////////////////////////////////////
final String sid = Settings.Secure.getString(app.getContentResolver(), Settings.Secure.ANDROID_ID);
if (!Utils.isNullOrEmpty(sid)) {
return UniqueId.newInstance(sid, UniqueId.Type.sid);
}
////////////////////////////////////////////////////////////////////////////////////////////
// INSTANCE ID
////////////////////////////////////////////////////////////////////////////////////////////
final String iid = com.google.android.gms.iid.InstanceID.getInstance(MyApplication.instance()).getId();
if (!Utils.isNullOrEmpty(iid)) {
return UniqueId.newInstance(iid, UniqueId.Type.iid);
}
return null;
}
public final class UniqueId implements Parcelable {
public enum Type implements Parcelable {
aid,
sid,
iid,
eid;
////////////////////////////////////////////////////////////////////////////
// Handling Parcelable nicely.
public static final Parcelable.Creator<Type> CREATOR = new Parcelable.Creator<Type>() {
public Type createFromParcel(Parcel in) {
return Type.valueOf(in.readString());
}
public Type[] newArray(int size) {
return new Type[size];
}
};
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel parcel, int flags) {
parcel.writeString(this.name());
}
// Handling Parcelable nicely.
////////////////////////////////////////////////////////////////////////////
}
public static boolean isValid(UniqueId uniqueId) {
if (uniqueId == null) {
return false;
}
return uniqueId.isValid();
}
private boolean isValid() {
return !org.yccheok.jstock.gui.Utils.isNullOrEmpty(id) && type != null;
}
private UniqueId(String id, Type type) {
if (org.yccheok.jstock.gui.Utils.isNullOrEmpty(id) || type == null) {
throw new java.lang.IllegalArgumentException();
}
this.id = id;
this.type = type;
}
public static UniqueId newInstance(String id, Type type) {
return new UniqueId(id, type);
}
@Override
public int hashCode() {
int result = 17;
result = 31 * result + id.hashCode();
result = 31 * result + type.hashCode();
return result;
}
@Override
public boolean equals(Object o) {
if (o == this) {
return true;
}
if (!(o instanceof UniqueId)) {
return false;
}
UniqueId uniqueId = (UniqueId)o;
return this.id.equals(uniqueId.id) && this.type == uniqueId.type;
}
@Override
public String toString() {
return type + ":" + id;
}
////////////////////////////////////////////////////////////////////////////
// Handling Parcelable nicely.
public static final Parcelable.Creator<UniqueId> CREATOR = new Parcelable.Creator<UniqueId>() {
public UniqueId createFromParcel(Parcel in) {
return new UniqueId(in);
}
public UniqueId[] newArray(int size) {
return new UniqueId[size];
}
};
private UniqueId(Parcel in) {
this.id = in.readString();
this.type = in.readParcelable(Type.class.getClassLoader());
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel parcel, int flags) {
parcel.writeString(this.id);
parcel.writeParcelable(this.type, 0);
}
// Handling Parcelable nicely.
////////////////////////////////////////////////////////////////////////////
public final String id;
public final Type type;
}
public static String getEmail() {
Pattern emailPattern = Patterns.EMAIL_ADDRESS; // API level 8+
AccountManager accountManager = AccountManager.get(MyApplication.instance());
Account[] accounts = accountManager.getAccountsByType("com.google");
for (Account account : accounts) {
if (emailPattern.matcher(account.name).matches()) {
String possibleEmail = account.name;
return possibleEmail;
}
}
accounts = accountManager.getAccounts();
for (Account account : accounts) {
if (emailPattern.matcher(account.name).matches()) {
String possibleEmail = account.name;
return possibleEmail;
}
}
return null;
}
Adding a background image to a <div> element
Use like ..
<div style="background-image: url(../images/test-background.gif); height: 200px; width: 400px; border: 1px solid black;">Example of a DIV element with a background image:</div>
<div style="background-image: url(../images/test-background.gif); height: 200px; width: 400px; border: 1px solid black;"> </div>
foreach vs someList.ForEach(){}
For fun, I popped List into reflector and this is the resulting C#:
public void ForEach(Action<T> action)
{
if (action == null)
{
ThrowHelper.ThrowArgumentNullException(ExceptionArgument.match);
}
for (int i = 0; i < this._size; i++)
{
action(this._items[i]);
}
}
Similarly, the MoveNext in Enumerator which is what is used by foreach is this:
public bool MoveNext()
{
if (this.version != this.list._version)
{
ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumFailedVersion);
}
if (this.index < this.list._size)
{
this.current = this.list._items[this.index];
this.index++;
return true;
}
this.index = this.list._size + 1;
this.current = default(T);
return false;
}
The List.ForEach is much more trimmed down than MoveNext - far less processing - will more likely JIT into something efficient..
In addition, foreach() will allocate a new Enumerator no matter what. The GC is your friend, but if you're doing the same foreach repeatedly, this will make more throwaway objects, as opposed to reusing the same delegate - BUT - this is really a fringe case. In typical usage you will see little or no difference.
Create text file and fill it using bash
If you're wanting this as a script, the following Bash script should do what you want (plus tell you when the file already exists):
#!/bin/bash
if [ -e $1 ]; then
echo "File $1 already exists!"
else
echo >> $1
fi
If you don't want the "already exists" message, you can use:
#!/bin/bash
if [ ! -e $1 ]; then
echo >> $1
fi
Edit about using:
Save whichever version with a name you like, let's say "create_file" (quotes mine, you don't want them in the file name). Then, to make the file executatble, at a command prompt do:
chmod u+x create_file
Put the file in a directory in your path, then use it with:
create_file NAME_OF_NEW_FILE
The $1 is a special shell variable which takes the first argument on the command line after the program name; i.e. $1 will pick up NAME_OF_NEW_FILE in the above usage example.
How do I correctly setup and teardown for my pytest class with tests?
According to Fixture finalization / executing teardown code, the current best practice for setup and teardown is to use yield
instead of return
:
import pytest
@pytest.fixture()
def resource():
print("setup")
yield "resource"
print("teardown")
class TestResource:
def test_that_depends_on_resource(self, resource):
print("testing {}".format(resource))
Running it results in
$ py.test --capture=no pytest_yield.py
=== test session starts ===
platform darwin -- Python 2.7.10, pytest-3.0.2, py-1.4.31, pluggy-0.3.1
collected 1 items
pytest_yield.py setup
testing resource
.teardown
=== 1 passed in 0.01 seconds ===
Another way to write teardown code is by accepting a request
-context object into your fixture function and calling its request.addfinalizer
method with a function that performs the teardown one or multiple times:
import pytest
@pytest.fixture()
def resource(request):
print("setup")
def teardown():
print("teardown")
request.addfinalizer(teardown)
return "resource"
class TestResource:
def test_that_depends_on_resource(self, resource):
print("testing {}".format(resource))
How do I download a tarball from GitHub using cURL?
All the other solutions require specifying a release/version number which obviously breaks automation.
This solution- currently tested and known to work with Github API v3- however can be used programmatically to grab the LATEST release without specifying any tag or release number and un-TARs the binary to an arbitrary name you specify in switch --one-top-level="pi-ap"
. Just swap-out user f1linux and repo pi-ap in below example with your own details and Bob's your uncle:
curl -L https://api.github.com/repos/f1linux/pi-ap/tarball | tar xzvf - --one-top-level="pi-ap" --strip-components 1
How to get Git to clone into current directory
To be sure that you could clone the repo, go to any temporary directory and clone the project there:
git clone ssh://[email protected]/home/user/private/repos/project_hub.git
This will clone your stuff into a project_hub
directory.
Once the cloning has finished, you could move this directory wherever you want:
mv project_hub /path/to/new/location
This is safe and doesn't require any magical stuff around.
Init array of structs in Go
Adding this just as an addition to @jimt's excellent answer:
one common way to define it all at initialization time is using an anonymous struct:
var opts = []struct {
shortnm byte
longnm, help string
needArg bool
}{
{'a', "multiple", "Usage for a", false},
{
shortnm: 'b',
longnm: "b-option",
needArg: false,
help: "Usage for b",
},
}
This is commonly used for testing as well to define few test cases and loop through them.
java Compare two dates
java.util.Date class has before and after method to compare dates.
Date date1 = new Date();
Date date2 = new Date();
if(date1.before(date2)){
//Do Something
}
if(date1.after(date2)){
//Do Something else
}
Creating a BAT file for python script
Here's how you can put both batch code and the python one in single file:
0<0# : ^
'''
@echo off
echo batch code
python "%~f0" %*
exit /b 0
'''
print("python code")
the '''
respectively starts and ends python multi line comments.
0<0# : ^
is more interesting - due to redirection priority in batch it will be interpreted like :0<0# ^
by the batch script which is a label which execution will be not displayed on the screen. The caret at the end will escape the new line and second line will be attached to the first line.For python it will be 0<0
statement and a start of inline comment.
The credit goes to siberia-man
Git pull - Please move or remove them before you can merge
If you are getting error like
- branch master -> FETCH_HEAD
error: The following untracked working tree files would be overwritten by merge:
src/dj/abc.html
Please move or remove them before you merge.
Aborting
Try removing the above file manually(Careful). Git will merge this file from master branch.
Displaying a webcam feed using OpenCV and Python
Try adding the line c = cv.WaitKey(10)
at the bottom of your repeat()
method.
This waits for 10 ms for the user to enter a key. Even if you're not using the key at all, put this in. I think there just needed to be some delay, so time.sleep(10)
may also work.
In regards to the camera index, you could do something like this:
for i in range(3):
capture = cv.CaptureFromCAM(i)
if capture: break
This will find the index of the first "working" capture device, at least for indices from 0-2. It's possible there are multiple devices in your computer recognized as a proper capture device. The only way I know of to confirm you have the right one is manually looking at your light. Maybe get an image and check its properties?
To add a user prompt to the process, you could bind a key to switching cameras in your repeat loop:
import cv
cv.NamedWindow("w1", cv.CV_WINDOW_AUTOSIZE)
camera_index = 0
capture = cv.CaptureFromCAM(camera_index)
def repeat():
global capture #declare as globals since we are assigning to them now
global camera_index
frame = cv.QueryFrame(capture)
cv.ShowImage("w1", frame)
c = cv.WaitKey(10)
if(c=="n"): #in "n" key is pressed while the popup window is in focus
camera_index += 1 #try the next camera index
capture = cv.CaptureFromCAM(camera_index)
if not capture: #if the next camera index didn't work, reset to 0.
camera_index = 0
capture = cv.CaptureFromCAM(camera_index)
while True:
repeat()
disclaimer: I haven't tested this so it may have bugs or just not work, but might give you at least an idea of a workaround.
How to change Oracle default data pump directory to import dumpfile?
I want change default directory dumpfile.
You could create a new directory and give it required privileges, for example:
SQL> CREATE DIRECTORY dmpdir AS '/opt/oracle';
Directory created.
SQL> GRANT read, write ON DIRECTORY dmpdir TO scott;
Grant succeeded.
To use the newly created directory, you could just add it as a parameter:
DIRECTORY=dmpdir
Oracle introduced a default directory from 10g R2, called DATA_PUMP_DIR, that can be used. To check the location, you could look into dba_directories:
SQL> select DIRECTORY_NAME, DIRECTORY_PATH from dba_directories where DIRECTORY_NAME = 'DATA_PUMP_DIR';
DIRECTORY_NAME DIRECTORY_PATH
-------------------- --------------------------------------------------
DATA_PUMP_DIR C:\app\Lalit/admin/orcl/dpdump/
SQL>
.war vs .ear file
To make the project transport, deployment made easy.
need to compressed into one file.
JAR (java archive) group of .class files
WAR (web archive) - each war represents one web application
- use only web related technologies like servlet, jsps can be used.
- can run on Tomcat server
- web app developed by web related technologies only jsp servlet html js
- info representation only no transactions.
EAR (enterprise archive) - each ear represents one enterprise application
- we can use anything from j2ee like ejb, jms can happily be used.
- can run on Glassfish like server not on Tomcat server.
- enterprise app devloped by any technology anything from j2ee like all web
app plus ejbs jms etc.
- does transactions with info representation. eg. Bank app, Telecom app
How to print out more than 20 items (documents) in MongoDB's shell?
Could always do:
db.foo.find().forEach(function(f){print(tojson(f, '', true));});
To get that compact view.
Also, I find it very useful to limit the fields returned by the find so:
db.foo.find({},{name:1}).forEach(function(f){print(tojson(f, '', true));});
which would return only the _id and name field from foo.
Get a list of resources from classpath directory
Here is the code
Source: forums.devx.com/showthread.php?t=153784
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.regex.Pattern;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;
import java.util.zip.ZipFile;
/**
* list resources available from the classpath @ *
*/
public class ResourceList{
/**
* for all elements of java.class.path get a Collection of resources Pattern
* pattern = Pattern.compile(".*"); gets all resources
*
* @param pattern
* the pattern to match
* @return the resources in the order they are found
*/
public static Collection<String> getResources(
final Pattern pattern){
final ArrayList<String> retval = new ArrayList<String>();
final String classPath = System.getProperty("java.class.path", ".");
final String[] classPathElements = classPath.split(System.getProperty("path.separator"));
for(final String element : classPathElements){
retval.addAll(getResources(element, pattern));
}
return retval;
}
private static Collection<String> getResources(
final String element,
final Pattern pattern){
final ArrayList<String> retval = new ArrayList<String>();
final File file = new File(element);
if(file.isDirectory()){
retval.addAll(getResourcesFromDirectory(file, pattern));
} else{
retval.addAll(getResourcesFromJarFile(file, pattern));
}
return retval;
}
private static Collection<String> getResourcesFromJarFile(
final File file,
final Pattern pattern){
final ArrayList<String> retval = new ArrayList<String>();
ZipFile zf;
try{
zf = new ZipFile(file);
} catch(final ZipException e){
throw new Error(e);
} catch(final IOException e){
throw new Error(e);
}
final Enumeration e = zf.entries();
while(e.hasMoreElements()){
final ZipEntry ze = (ZipEntry) e.nextElement();
final String fileName = ze.getName();
final boolean accept = pattern.matcher(fileName).matches();
if(accept){
retval.add(fileName);
}
}
try{
zf.close();
} catch(final IOException e1){
throw new Error(e1);
}
return retval;
}
private static Collection<String> getResourcesFromDirectory(
final File directory,
final Pattern pattern){
final ArrayList<String> retval = new ArrayList<String>();
final File[] fileList = directory.listFiles();
for(final File file : fileList){
if(file.isDirectory()){
retval.addAll(getResourcesFromDirectory(file, pattern));
} else{
try{
final String fileName = file.getCanonicalPath();
final boolean accept = pattern.matcher(fileName).matches();
if(accept){
retval.add(fileName);
}
} catch(final IOException e){
throw new Error(e);
}
}
}
return retval;
}
/**
* list the resources that match args[0]
*
* @param args
* args[0] is the pattern to match, or list all resources if
* there are no args
*/
public static void main(final String[] args){
Pattern pattern;
if(args.length < 1){
pattern = Pattern.compile(".*");
} else{
pattern = Pattern.compile(args[0]);
}
final Collection<String> list = ResourceList.getResources(pattern);
for(final String name : list){
System.out.println(name);
}
}
}
If you are using Spring Have a look at PathMatchingResourcePatternResolver
Not able to pip install pickle in python 3.6
$ pip install pickle5
import pickle5 as pickle
pb = pickle.PickleBuffer(b"foo")
data = pickle.dumps(pb, protocol=5)
assert pickle.loads(data) == b"foo"
This package backports all features and APIs added in the pickle module in Python 3.8.3, including the PEP 574 additions. It should work with Python 3.5, 3.6 and 3.7.
Basic usage is similar to the pickle module, except that the module to be imported is pickle5:
https://pypi.org/project/pickle5/
A SELECT statement that assigns a value to a variable must not be combined with data-retrieval operations
You cannot use a select statement that assigns values to variables to also return data to the user
The below code will work fine, because i have declared 1 local variable and that variable is used in select statement.
Begin
DECLARE @name nvarchar(max)
select @name=PolicyHolderName from Table
select @name
END
The below code will throw error "A SELECT statement that assigns a value to a variable
must not be combined with data-retrieval operations" Because we are retriving data(PolicyHolderAddress) from table, but error says data-retrieval operation is not allowed when you use some local variable as part of select statement.
Begin
DECLARE @name nvarchar(max)
select
@name = PolicyHolderName,
PolicyHolderAddress
from Table
END
The the above code can be corrected like below,
Begin
DECLARE @name nvarchar(max)
DECLARE @address varchar(100)
select
@name = PolicyHolderName,
@address = PolicyHolderAddress
from Table
END
So either remove the data-retrieval operation or add extra local variable. This will resolve the error.
How to do multiline shell script in Ansible
Ansible uses YAML syntax in its playbooks. YAML has a number of block operators:
The >
is a folding block operator. That is, it joins multiple lines together by spaces. The following syntax:
key: >
This text
has multiple
lines
Would assign the value This text has multiple lines\n
to key
.
The |
character is a literal block operator. This is probably what you want for multi-line shell scripts. The following syntax:
key: |
This text
has multiple
lines
Would assign the value This text\nhas multiple\nlines\n
to key
.
You can use this for multiline shell scripts like this:
- name: iterate user groups
shell: |
groupmod -o -g {{ item['guid'] }} {{ item['username'] }}
do_some_stuff_here
and_some_other_stuff
with_items: "{{ users }}"
There is one caveat: Ansible does some janky manipulation of arguments to the shell
command, so while the above will generally work as expected, the following won't:
- shell: |
cat <<EOF
This is a test.
EOF
Ansible will actually render that text with leading spaces, which means the shell will never find the string EOF
at the beginning of a line. You can avoid Ansible's unhelpful heuristics by using the cmd
parameter like this:
- shell:
cmd: |
cat <<EOF
This is a test.
EOF
How to sum columns in a dataTable?
There is also a way to do this without loops using the DataTable.Compute Method. The following example comes from that page. You can see that the code used is pretty simple.:
private void ComputeBySalesSalesID(DataSet dataSet)
{
// Presumes a DataTable named "Orders" that has a column named "Total."
DataTable table;
table = dataSet.Tables["Orders"];
// Declare an object variable.
object sumObject;
sumObject = table.Compute("Sum(Total)", "EmpID = 5");
}
I must add that if you do not need to filter the results, you can always pass an empty string:
sumObject = table.Compute("Sum(Total)", "")
In practice, what are the main uses for the new "yield from" syntax in Python 3.3?
This code defines a function fixed_sum_digits
returning a generator enumerating all six digits numbers such that the sum of digits is 20.
def iter_fun(sum, deepness, myString, Total):
if deepness == 0:
if sum == Total:
yield myString
else:
for i in range(min(10, Total - sum + 1)):
yield from iter_fun(sum + i,deepness - 1,myString + str(i),Total)
def fixed_sum_digits(digits, Tot):
return iter_fun(0,digits,"",Tot)
Try to write it without yield from
. If you find an effective way to do it let me know.
I think that for cases like this one: visiting trees, yield from
makes the code simpler and cleaner.
Returning a file to View/Download in ASP.NET MVC
Action method needs to return FileResult with either a stream, byte[], or virtual path of the file. You will also need to know the content-type of the file being downloaded. Here is a sample (quick/dirty) utility method. Sample video link
How to download files using asp.net core
[Route("api/[controller]")]
public class DownloadController : Controller
{
[HttpGet]
public async Task<IActionResult> Download()
{
var path = @"C:\Vetrivel\winforms.png";
var memory = new MemoryStream();
using (var stream = new FileStream(path, FileMode.Open))
{
await stream.CopyToAsync(memory);
}
memory.Position = 0;
var ext = Path.GetExtension(path).ToLowerInvariant();
return File(memory, GetMimeTypes()[ext], Path.GetFileName(path));
}
private Dictionary<string, string> GetMimeTypes()
{
return new Dictionary<string, string>
{
{".txt", "text/plain"},
{".pdf", "application/pdf"},
{".doc", "application/vnd.ms-word"},
{".docx", "application/vnd.ms-word"},
{".png", "image/png"},
{".jpg", "image/jpeg"},
...
};
}
}
How to convert webpage into PDF by using Python
Here is a simple solution using QT. I found this as part of an answer to a different question on StackOverFlow. I tested it on Windows.
from PyQt4.QtGui import QTextDocument, QPrinter, QApplication
import sys
app = QApplication(sys.argv)
doc = QTextDocument()
location = "c://apython//Jim//html//notes.html"
html = open(location).read()
doc.setHtml(html)
printer = QPrinter()
printer.setOutputFileName("foo.pdf")
printer.setOutputFormat(QPrinter.PdfFormat)
printer.setPageSize(QPrinter.A4);
printer.setPageMargins (15,15,15,15,QPrinter.Millimeter);
doc.print_(printer)
print "done!"
summing two columns in a pandas dataframe
If "budget" has any NaN values but you don't want it to sum to NaN then try:
def fun (b, a):
if math.isnan(b):
return a
else:
return b + a
f = np.vectorize(fun, otypes=[float])
df['variance'] = f(df['budget'], df_Lp['actual'])
PHP max_input_vars
Yes, add it to the php.ini, restart apache and it should work.
You can test it on the fly if you want to with ini_set("max_input_vars",100)
grep --ignore-case --only
It should be a problem in your version of grep.
Your test cases are working correctly here on my machine:
$ echo "abc" | grep -io abc
abc
$ echo "ABC" | grep -io abc
ABC
And my version is:
$ grep --version
grep (GNU grep) 2.10
Android Firebase, simply get one child object's data
I store my data this way:
accountsTable ->
key1 -> account1
key2 -> account2
in order to get object data:
accountsDb = mDatabase.child("accountsTable");
accountsDb.child("some key").addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
try{
Account account = snapshot.getChildren().iterator().next()
.getValue(Account.class);
} catch (Throwable e) {
MyLogger.error(this, "onCreate eror", e);
}
}
@Override public void onCancelled(DatabaseError error) { }
});
Angular 4 - get input value
You can use (keyup)
or (change)
events, see example below:
in HTML:
<input (keyup)="change($event)">
Or
<input (change)="change($event)">
in Component:
change(event) {console.log(event.target.value);}
How to Install Font Awesome in Laravel Mix
the path you are using is not correct you could just open the node_module and find the path of font-awesome.
use could use js or svg font but i prefer the css style.
at first use this command to install font-awesome-free
npm install --save-dev @fortawesome/fontawesome-free
after that you can do this
@import "~@fortawesome/fontawesome-free/scss/fontawesome";
@import "~@fortawesome/fontawesome-free/scss/regular";
@import "~@fortawesome/fontawesome-free/scss/solid";
@import "~@fortawesome/fontawesome-free/scss/brands";
and I copy the font path like below this is optional
.copy('node_modules/@fortawesome/fontawesome-free/webfonts', 'public/fonts');
and finally just run the script
npm run dev
or npm run watch
in laravel
How to split a delimited string in Ruby and convert it to an array?
>> "1,2,3,4".split(",")
=> ["1", "2", "3", "4"]
Or for integers:
>> "1,2,3,4".split(",").map { |s| s.to_i }
=> [1, 2, 3, 4]
Or for later versions of ruby (>= 1.9 - as pointed out by Alex):
>> "1,2,3,4".split(",").map(&:to_i)
=> [1, 2, 3, 4]
C++: Converting Hexadecimal to Decimal
std::cout << "Enter decimal number: " ;
std::cin >> input ;
std::cout << "0x" << std::hex << input << '\n' ;
if your adding a input that can be a boolean or float or int it will be passed back in the int main function call...
With function templates, based on argument types, C generates separate functions to handle each type of call appropriately. All function template definitions begin with the keyword template followed by arguments enclosed in angle brackets < and >. A single formal parameter T is used for the type of data to be tested.
Consider the following program where the user is asked to enter an integer and then a float, each uses the square function to determine the square.
With function templates, based on argument types, C generates separate functions to handle each type of call appropriately. All function template definitions begin with the keyword template followed by arguments enclosed in angle brackets < and >. A single formal parameter T is used for the type of data to be tested.
Consider the following program where the user is asked to enter an integer and then a float, each uses the square function to determine the square.
#include <iostream>
using namespace std;
template <class T> // function template
T square(T); /* returns a value of type T and accepts type T (int or float or whatever) */
void main()
{
int x, y;
float w, z;
cout << "Enter a integer: ";
cin >> x;
y = square(x);
cout << "The square of that number is: " << y << endl;
cout << "Enter a float: ";
cin >> w;
z = square(w);
cout << "The square of that number is: " << z << endl;
}
template <class T> // function template
T square(T u) //accepts a parameter u of type T (int or float)
{
return u * u;
}
Here is the output:
Enter a integer: 5
The square of that number is: 25
Enter a float: 5.3
The square of that number is: 28.09
Zookeeper connection error
I just have the same situation as you and I have just fixed this problem.
It is the reason that you have configured even number of zookeepers which directly result in
this problem,try to change your number of zookeeper node to a odd one.
for example the original status of my zookeeper cluster is consisted of 4 nodes,then just remove one of them which result in the number of node to be 3
well ,now its ok to startup zookeeper cluster
below is the output of successfully connect to zookeeper server
2013-04-22 22:07:05,654 [myid:] - INFO [main:ZooKeeper@438] - Initiating client connection, connectString=localhost:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@1321ed6
Welcome to ZooKeeper!
2013-04-22 22:07:05,704 [myid:] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@966] - Opening socket connection to server localhost/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error)
JLine support is enabled
2013-04-22 22:07:05,727 [myid:] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@849] - Socket connection established to localhost/127.0.0.1:2181, initiating session
[zk: localhost:2181(CONNECTING) 0] 2013-04-22 22:07:05,846 [myid:] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1207] - Session establishment complete on server localhost/127.0.0.1:2181, sessionid = 0x13e3211c06e0000, negotiated timeout = 30000