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Some Of The Best Answers From Latest Asked Questions

Add column in dataframe from list

First let's create the dataframe you had, I'll ignore columns B and C as they are not relevant.

df = pd.DataFrame({'A': [0, 4, 5, 6, 7, 7, 6,5]})

And the mapping that you desire:

mapping = dict(enumerate([2,5,6,8,12,16,26,32]))

df['D'] = df['A'].map(mapping)


print df


   A   D
0  0   2
1  4  12
2  5  16
3  6  26
4  7  32
5  7  32
6  6  26
7  5  16

Removing NA in dplyr pipe

I don't think desc takes an na.rm argument... I'm actually surprised it doesn't throw an error when you give it one. If you just want to remove NAs, use na.omit (base) or tidyr::drop_na:

outcome.df %>%
  na.omit() %>%
  group_by(Hospital, State) %>%
  arrange(desc(HeartAttackDeath)) %>%

outcome.df %>%
  drop_na() %>%
  group_by(Hospital, State) %>%
  arrange(desc(HeartAttackDeath)) %>%

If you only want to remove NAs from the HeartAttackDeath column, filter with, or use tidyr::drop_na:

outcome.df %>%
  filter(! %>%
  group_by(Hospital, State) %>%
  arrange(desc(HeartAttackDeath)) %>%

outcome.df %>%
  drop_na(HeartAttackDeath) %>%
  group_by(Hospital, State) %>%
  arrange(desc(HeartAttackDeath)) %>%

As pointed out at the dupe, complete.cases can also be used, but it's a bit trickier to put in a chain because it takes a data frame as an argument but returns an index vector. So you could use it like this:

outcome.df %>%
  filter(complete.cases(.)) %>%
  group_by(Hospital, State) %>%
  arrange(desc(HeartAttackDeath)) %>%

Why can I not create a wheel in python?

It could also be that you have a python3 system only. You therefore have installed the necessary packages via pip3 install , like pip3 install wheel.

You'll need to build your stuff using python3 specifically.

python3 sdist
python3 bdist_wheel


What does Include() do in LINQ?

Think of it as enforcing Eager-Loading in a scenario where you sub-items would otherwise be lazy-loading.

The Query EF is sending to the database will yield a larger result at first, but on access no follow-up queries will be made when accessing the included items.

On the other hand, without it, EF would execute separte queries later, when you first access the sub-items.

How do I print the key-value pairs of a dictionary in python

A little intro to dictionary

d.keys()  # displays all keys in list
d.values() # displays your values in list
d.items() # displays your pair tuple of key and value

Print keys,values method one

for x in d.keys():
    print x +" => " + d[x]

Another method

for key,value in d.items():
    print key + " => " + value

You can get keys using iter

>>> list(iter(d))
['a', 'b']

You can get value of key of dictionary using get(key, [value]):


If key is not present in dictionary,when default value given, will return value.

d.get('c', 'Cat')

cat, grep and cut - translated to python

You need to have better understanding of the python language and its standard library to translate the expression

cat "$filename": Reads the file cat "$filename" and dumps the content to stdout

|: pipe redirects the stdout from previous command and feeds it to the stdin of the next command

grep "something": Searches the regular expressionsomething plain text data file (if specified) or in the stdin and returns the matching lines.

cut -d'"' -f2: Splits the string with the specific delimiter and indexes/splices particular fields from the resultant list

Python Equivalent

cat "$filename"  | with open("$filename",'r') as fin:        | Read the file Sequentially
                 |     for line in fin:                      |   
grep 'something' | import re                                 | The python version returns
                 | line = re.findall(r'something', line)[0]  | a list of matches. We are only
                 |                                           | interested in the zero group
cut -d'"' -f2    | line = line.split('"')[1]                 | Splits the string and selects
                 |                                           | the second field (which is
                 |                                           | index 1 in python)


import re
with open("filename") as origin_file:
    for line in origin_file:
        line = re.findall(r'something', line)
        if line:
           line = line[0].split('"')[1]
        print line

getting the index of a row in a pandas apply function


1. with inside the apply(..., axis=1) call:

df = pandas.DataFrame([[1,2,3],[4,5,6]], columns=['a','b','c'], index=['x','y'])

   a  b  c
x  1  2  3
y  4  5  6

df.apply(lambda row:, axis=1)

x    x
y    y

2. with iterrows() (slower)

DataFrame.iterrows() allows you to iterate over rows, and access their index:

for idx, row in df.iterrows():

Installing NumPy and SciPy on 64-bit Windows (with Pip)

You can download the needed packages from here and use pip install "Abc.whl" from the directory where you have downloaded the file.

Passing parameters from jsp to Spring Controller method

Your controller method should be like this:

@RequestMapping(value = " /<your mapping>/{id}", method=RequestMethod.GET)
public String listNotes(@PathVariable("id")int id,Model model) {
    Person person = personService.getCurrentlyAuthenticatedUser();
    int id = 2323;  // Currently passing static values for testing
    model.addAttribute("person", new Person());
    model.addAttribute("listPersons", this.personService.listPersons());
    return "note";

Use the id in your code, call the controller method from your JSP as:

/{your mapping}/{your id}


Change your jsp code to:

<c:forEach items="${listNotes}" var="notices" varStatus="status">
        <td><a href="<c:url value='/editnote/${listNotes[status.index].noticesid}' />" >Edit</a></td>
        <td><a href="<c:url value='/removenote/${listNotes[status.index].noticesid}' />" >Delete</a></td>

Display Back Arrow on Toolbar

    Toolbar toolbar = (Toolbar) findViewById(;
    toolbar.setNavigationIcon(R.drawable.back_arrow); // your drawable
    toolbar.setNavigationOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            onBackPressed(); // Implemented by activity

And for API 21+ android:navigationIcon


How to show PIL Image in ipython notebook

You can open an image using the Image class from the package PIL and display it with plt.imshow directly.

# First import libraries.
from PIL import Image
import matplotlib.pyplot as plt

# The folliwing line is useful in Jupyter notebook
%matplotlib inline

# Open your file image using the path
img =<path_to_image>)

# Since plt knows how to handle instance of the Image class, just input your loaded image to imshow method

Nested Recycler view height doesn't wrap its content

Used solution from @sinan-kozak, except fixed a few bugs. Specifically, we shouldn't use View.MeasureSpec.UNSPECIFIED for both the width and height when calling measureScrapChild as that won't properly account for wrapped text in the child. Instead, we will pass through the width and height modes from the parent which will allow things to work for both horizontal and vertical layouts.

public class MyLinearLayoutManager extends LinearLayoutManager {

public MyLinearLayoutManager(Context context, int orientation, boolean reverseLayout)    {
    super(context, orientation, reverseLayout);

private int[] mMeasuredDimension = new int[2];

public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
                      int widthSpec, int heightSpec) {
    final int widthMode = View.MeasureSpec.getMode(widthSpec);
    final int heightMode = View.MeasureSpec.getMode(heightSpec);
    final int widthSize = View.MeasureSpec.getSize(widthSpec);
    final int heightSize = View.MeasureSpec.getSize(heightSpec);
    int width = 0;
    int height = 0;
    for (int i = 0; i < getItemCount(); i++) {    
        if (getOrientation() == HORIZONTAL) {
            measureScrapChild(recycler, i,
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
                View.MeasureSpec.makeMeasureSpec(heightSize, heightMode),

            width = width + mMeasuredDimension[0];
            if (i == 0) {
                height = mMeasuredDimension[1];
        } else {
            measureScrapChild(recycler, i,
                View.MeasureSpec.makeMeasureSpec(widthSize, widthMode),
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),

            height = height + mMeasuredDimension[1];
            if (i == 0) {
                width = mMeasuredDimension[0];

    // If child view is more than screen size, there is no need to make it wrap content. We can use original onMeasure() so we can scroll view.
    if (height < heightSize && width < widthSize) {

        switch (widthMode) {
            case View.MeasureSpec.EXACTLY:
                width = widthSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:

        switch (heightMode) {
            case View.MeasureSpec.EXACTLY:
                height = heightSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:

        setMeasuredDimension(width, height);
    } else {
        super.onMeasure(recycler, state, widthSpec, heightSpec);

private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                               int heightSpec, int[] measuredDimension) {

   View view = recycler.getViewForPosition(position);

   // For adding Item Decor Insets to view
   super.measureChildWithMargins(view, 0, 0);
    if (view != null) {
        RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
        int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                    getPaddingLeft() + getPaddingRight() + getDecoratedLeft(view) + getDecoratedRight(view), p.width);
            int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                    getPaddingTop() + getPaddingBottom() + getDecoratedTop(view) + getDecoratedBottom(view) , p.height);
            view.measure(childWidthSpec, childHeightSpec);

            // Get decorated measurements
            measuredDimension[0] = getDecoratedMeasuredWidth(view) + p.leftMargin + p.rightMargin;
            measuredDimension[1] = getDecoratedMeasuredHeight(view) + p.bottomMargin + p.topMargin;


How to check if a Java 8 Stream is empty?

If you can live with limited parallel capablilities, the following solution will work:

private static <T> Stream<T> nonEmptyStream(
    Stream<T> stream, Supplier<RuntimeException> e) {

    Spliterator<T> it=stream.spliterator();
    return Spliterator<T>() {
        boolean seen;
        public boolean tryAdvance(Consumer<? super T> action) {
            boolean r=it.tryAdvance(action);
            if(!seen && !r) throw e.get();
            return r;
        public Spliterator<T> trySplit() { return null; }
        public long estimateSize() { return it.estimateSize(); }
        public int characteristics() { return it.characteristics(); }
    }, false);

Here is some example code using it:

List<String> l=Arrays.asList("hello", "world");
nonEmptyStream(, ()->new RuntimeException("No strings available"))
               ()->new RuntimeException("No strings available"))

The problem with (efficient) parallel execution is that supporting splitting of the Spliterator requires a thread-safe way to notice whether either of the fragments has seen any value in a thread-safe manner. Then the last of the fragments executing tryAdvance has to realize that it is the last one (and it also couldn’t advance) to throw the appropriate exception. So I didn’t add support for splitting here.

Remove title in Toolbar in appcompat-v7

toolbar.setTitle(null);// remove the title

Homebrew: Could not symlink, /usr/local/bin is not writable

I've found the following relevant for Sophos Anti-Virus users:

In short, Sophos is changing permissions of certain /usr/local directories. Sophos has patched this and the fix is included with version 9.4.1.

Purpose of installing Twitter Bootstrap through npm?

If you NPM those modules you can serve them using static redirect.

First install the packages:

npm install jquery
npm install bootstrap

Then on the server.js:

var express = require('express');
var app = express();

// prepare server
app.use('/api', api); // redirect API calls
app.use('/', express.static(__dirname + '/www')); // redirect root
app.use('/js', express.static(__dirname + '/node_modules/bootstrap/dist/js')); // redirect bootstrap JS
app.use('/js', express.static(__dirname + '/node_modules/jquery/dist')); // redirect JS jQuery
app.use('/css', express.static(__dirname + '/node_modules/bootstrap/dist/css')); // redirect CSS bootstrap

Then, finally, at the .html:

<link rel="stylesheet" href="/css/bootstrap.min.css">
<script src="/js/jquery.min.js"></script>
<script src="/js/bootstrap.min.js"></script>

I would not serve pages directly from the folder where your server.js file is (which is usually the same as node_modules) as proposed by timetowonder, that way people can access your server.js file.

Of course you can simply download and copy & paste on your folder, but with NPM you can simply update when needed... easier, I think.

Convert Pandas Column to DateTime

raw_data['Mycol'] =  pd.to_datetime(raw_data['Mycol'], format='%d%b%Y:%H:%M:%S.%f')

works, however it results in a Python warning of A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc[row_indexer,col_indexer] = value instead

I would guess this is due to some chaining indexing.

MySQL stored procedure return value

You have done the stored procedure correctly but I think you have not referenced the valido variable properly. I was looking at some examples and they have put an @ symbol before the parameter like this @Valido

This statement SELECT valido; should be like this SELECT @valido;

Look at this link mysql stored-procedure: out parameter. Notice the solution with 7 upvotes. He has reference the parameter with an @ sign, hence I suggested you add an @ sign before your parameter valido

I hope that works for you. if it does vote up and mark it as the answer. If not, tell me.

How to store images in mysql database using php

(IF YOU HAVE ANY QUERY CONTACT:[email protected])

CREATE TABLE  `images` (
  `id` int(100) NOT NULL AUTO_INCREMENT,
  `name` varchar(100) NOT NULL,
  `image` longblob NOT NULL,
  PRIMARY KEY (`id`)

<!-- this form is user to store images-->
<form action="index.php" method="post"  enctype="multipart/form-data">
Enter the Image Name:<input type="text" name="image_name" id="" /><br />

<input name="image" id="image" accept="image/JPEG" type="file"><br /><br />
<input type="submit" value="submit" name="submit" />
<br /><br />
<!-- this form is user to display all the images-->
<form action="index.php" method="post"  enctype="multipart/form-data">
Retrive all the images:
<input type="submit" value="submit" name="retrive" />

//connect to database.db name is images
        mysql_connect("", "", "") OR DIE (mysql_error());
        mysql_select_db ("") OR DIE ("Unable to select db".mysql_error());
//to retrive send the page to another page


//to upload
if(isset($_FILES['image'])) {
        $fp=addslashes(file_get_contents($_FILES['image']['tmp_name'])); //will store the image to fp
                // our sql query
                $sql = "INSERT INTO images VALUES('null', '{$name}','{$fp}');";
                            mysql_query($sql) or die("Error in Query insert: " . mysql_error());

    //connect to database.db name = images
         mysql_connect("localhost", "root", "") OR DIE (mysql_error());
        mysql_select_db ("image") OR DIE ("Unable to select db".mysql_error());
//display all the image present in the database

        $sql="select * from images";

                  $msg.= '<a href="search.php?id='.$id.'"><img src="data:image/jpeg;base64,'.base64_encode($row['image']). ' " />   </a>';

            $msg.="Query failed";
echo $msg;

How to implement oauth2 server in ASP.NET MVC 5 and WEB API 2

Gmail: OAuth

  • Goto the link
  • Login with your gmail username password
  • Click on the google menu at the top left
  • Click API Manager
  • Click on Credentials
  • Click Create Credentials and select OAuth Client
  • Select Web Application as Application type and Enter the Name-> Enter Authorised Redirect URL (Eg: http://localhost:53922/signin-google) ->Click on Create button. This will create the credentials. Pls make a note of Client ID and Secret ID. Finally click OK to close the credentials pop up.
  • Next important step is to enable the Google API. Click on Overview in the left pane.
  • Click on the Google API under Social APIs section.
  • Click Enable.

That’s all from the Google part.

Come back to your application, open App_start/Startup.Auth.cs and uncomment the following snippet

        app.UseGoogleAuthentication(new GoogleOAuth2AuthenticationOptions()
            ClientId = "",
            ClientSecret = ""

Update the ClientId and ClientSecret with the values from Google API credentials which you have created already.

  • Run your application
  • Click Login
  • You will see the Google button under ‘Use Another Section to log in’ section
  • Click on the Google button
  • Application will prompt you to enter the username and password
  • Enter the gmail username and password and click Sign In
  • This will perform the OAuth and come back to your application and prompting you to register with the Gmail id.
  • Click register to register the Gmail id into your application database.
  • You will see the Identity details appear in the top as normal registration
  • Try logout and login again thru Gmail. This will automatically logs you into the app.

CSS disable hover effect

Here is way to to unset the hover effect.

.table-hover > tbody > tr.hidden-table:hover > td {
    background-color: unset !important;
    color: unset !important;

set initial viewcontroller in appdelegate - swift

I find this answer helpful and works perfectly for my case when i needed to change the rootviewcontroller if my app user already exist in the keychain or userdefault.

Efficiently getting all divisors of a given number

using namespace std;
typedef long long int ll;
#define MOD 1000000007
#define fo(i,k,n) for(int i=k;i<=n;++i)
#define endl '\n'
ll etf[1000001];
ll spf[1000001];
void sieve(){
    ll i,j;
    for(i=0;i<=1000000;i++) {etf[i]=i;spf[i]=i;}
void primefacto(ll n,vector<pair<ll,ll>>& vec){
    ll lastprime = 1,k=0;
void divisors(vector<pair<ll,ll>>& vec,ll idx,vector<ll>& divs,ll num){
    for(ll i=0;i<=vec[idx].second;i++){
void solve(){
    ll n;
    vector<pair<ll,ll>> vec;
    vector<ll> divs;
    for(auto it=divs.begin();it!=divs.end();it++){
int main(){
    ll t;cin>>t;
    while(t--) solve();
    return 0;

How to analyze disk usage of a Docker container

I use docker stats $(docker ps --format={{.Names}}) --no-stream to get :

  1. CPU usage,
  2. Mem usage/Total mem allocated to container (can be allocate with docker run command)
  3. Mem %
  4. Block I/O
  5. Net I/O

$rootScope.$broadcast vs. $scope.$emit

@Eddie has given a perfect answer of the question asked. But I would like to draw attention to using an more efficient approach of Pub/Sub.

As this answer suggests,

The $broadcast/$on approach is not terribly efficient as it broadcasts to all the scopes(Either in one direction or both direction of Scope hierarchy). While the Pub/Sub approach is much more direct. Only subscribers get the events, so it isn't going to every scope in the system to make it work.

you can use angular-PubSub angular module. once you add PubSub module to your app dependency, you can use PubSub service to subscribe and unsubscribe events/topics.

Easy to subscribe:

// Subscribe to event
var sub = PubSub.subscribe('event-name', function(topic, data){

Easy to publish

PubSub.publish('event-name', {
    prop1: value1,
    prop2: value2

To unsubscribe, use PubSub.unsubscribe(sub); OR PubSub.unsubscribe('event-name');.

NOTE Don't forget to unsubscribe to avoid memory leaks.

Best way to add Gradle support to IntelliJ Project

To add to other answers. For me it was helpful to delete .mvn directory and then add build.gradle. New versions of IntelliJ will then automatically notice that you use Gradle.

Converting dictionary to JSON

json.dumps() converts a dictionary to str object, not a json(dict) object! So you have to load your str into a dict to use it by using json.loads() method

See json.dumps() as a save method and json.loads() as a retrieve method.

This is the code sample which might help you understand it more:

import json

r = {'is_claimed': 'True', 'rating': 3.5}
r = json.dumps(r)
loaded_r = json.loads(r)
loaded_r['rating'] #Output 3.5
type(r) #Output str
type(loaded_r) #Output dict

Converting map to struct

The simplest way would be to use

import ""

mapstructure.Decode(myData, &result)

If you want to do it yourself, you could do something like this:

func SetField(obj interface{}, name string, value interface{}) error {
    structValue := reflect.ValueOf(obj).Elem()
    structFieldValue := structValue.FieldByName(name)

    if !structFieldValue.IsValid() {
        return fmt.Errorf("No such field: %s in obj", name)

    if !structFieldValue.CanSet() {
        return fmt.Errorf("Cannot set %s field value", name)

    structFieldType := structFieldValue.Type()
    val := reflect.ValueOf(value)
    if structFieldType != val.Type() {
        return errors.New("Provided value type didn't match obj field type")

    return nil

type MyStruct struct {
    Name string
    Age  int64

func (s *MyStruct) FillStruct(m map[string]interface{}) error {
    for k, v := range m {
        err := SetField(s, k, v)
        if err != nil {
            return err
    return nil

func main() {
    myData := make(map[string]interface{})
    myData["Name"] = "Tony"
    myData["Age"] = int64(23)

    result := &MyStruct{}
    err := result.FillStruct(myData)
    if err != nil {

The client and server cannot communicate, because they do not possess a common algorithm - ASP.NET C# IIS TLS 1.0 / 1.1 / 1.2 - Win32Exception

There are several other posts about this now and they all point to enabling TLS 1.2. Anything less is unsafe.

You can do this in .NET 3.5 with a patch.
You can do this in .NET 4.0 and 4.5 with a single line of code

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12; // .NET 4.5
ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072; // .NET 4.0

In .NET 4.6, it automatically uses TLS 1.2.

See here for more details: .NET support for TLS

IOException: The process cannot access the file 'file path' because it is being used by another process

Had an issue while uploading an image and couldn't delete it and found a solution. gl hf

//C# .NET
var image = Image.FromFile(filePath);

image.Dispose(); // this removes all resources


File.Delete(filePath); //now works

Virtualbox shared folder permissions

The issue is that the shared folder's permissions are set to not allow symbolic links by default. You can enable them in a few easy steps.

  1. Shut down the virtual machine.
  2. Note your machine name at Machine > Settings > General > Name
  3. Note your shared folder name at 'Machine > Settings > Shared Folders`
  4. Find your VirtualBox root directory and execute the following command. VBoxManage setextradata "" VBoxInternal2/SharedFoldersEnableSymlinksCreate/ 1
  5. Start up the virtual machine and the shared folder will now allow symbolic links.

JWT (JSON Web Token) automatic prolongation of expiration

How about this approach:

  • For every client request, the server compares the expirationTime of the token with (currentTime - lastAccessTime)
  • If expirationTime < (currentTime - lastAccessedTime), it changes the last lastAccessedTime to currentTime.
  • In case of inactivity on the browser for a time duration exceeding expirationTime or in case the browser window was closed and the expirationTime > (currentTime - lastAccessedTime), and then the server can expire the token and ask the user to login again.

We don't require additional end point for refreshing the token in this case. Would appreciate any feedack.

Android Studio SDK location

If your project is open click on Gradle Scripts > LOCATION), open it and there is the location of sdk with name


Note don't forget the replace \\ to \ before coping the things(sdk location)

How to add and remove classes in Javascript without jQuery

I'm using this simple code for this task:

CSS Code

.demo {
     background: tomato;
     color: white;

Javascript code

function myFunction() {
    /* Assign element to x variable by id  */
    var x = document.getElementById('para);

    if (x.hasAttribute('class') {      
    } else {
        x.setAttribute('class', 'demo');

yum error "Cannot retrieve metalink for repository: epel. Please verify its path and try again" updating ContextBroker

I encountered the same issue even though the ca-certificates package is up-to-date. The mirror is currently signed by DigiCert High Assurance EV Root CA which is included in my ca-bundle

$ grep -A 3 "DigiCert High" /etc/ssl/certs/ca-bundle.crt 
# DigiCert High Assurance EV Root CA

The reason why https connections failed in my case, was that system date was set to the year 2002 in which the DigiCert High Assurance EV Root CA is not (yet) valid.

$ date
Di 1. Jan 11:10:35 CET 2002

Changing the system time fixed the issue.

How to upgrade docker container after its image changed

Taking from

You can update all your existing images using the following command pipeline:

docker images | awk '/^REPOSITORY|\<none\>/ {next} {print $1}' | xargs -n 1 docker pull

Displaying the Error Messages in Laravel after being Redirected from controller

to Make it look nice you can use little bootstrap help

@if(count($errors) > 0 )
<div class="alert alert-danger alert-dismissible fade show" role="alert">
    <button type="button" class="close" data-dismiss="alert" aria-label="Close">
        <span aria-hidden="true">&times;</span>
    <ul class="p-0 m-0" style="list-style: none;">
        @foreach($errors->all() as $error)

How to remove provisioning profiles from Xcode

. Simple Steps:

1:Click finder

2:Right click on Finder
3:click on goto folder

4: Paste in Search : ~/Library/MobileDevice/Provisioning Profiles

5:Click on Go

6:List of the Profiles .you can delete any one


You'll want to restart XCode to refresh the list.

Ansible - Save registered variable to file

I am using Ansible 1.9.4 and this is what worked for me -

- local_action: copy content="{{ foo_result.stdout }}" dest="/path/to/destination/file"

RecyclerView vs. ListView

RecyclerView was created as a ListView improvement, so yes, you can create an attached list with ListView control, but using RecyclerView is easier as it:

  1. Reuses cells while scrolling up/down - this is possible with implementing View Holder in the ListView adapter, but it was an optional thing, while in the RecycleView it's the default way of writing adapter.

  2. Decouples list from its container - so you can put list items easily at run time in the different containers (linearLayout, gridLayout) with setting LayoutManager.


mRecyclerView = (RecyclerView) findViewById(;
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
mRecyclerView.setLayoutManager(new GridLayoutManager(this, 2));
  1. Animates common list actions - Animations are decoupled and delegated to ItemAnimator.

There is more about RecyclerView, but I think these points are the main ones.

So, to conclude, RecyclerView is a more flexible control for handling "list data" that follows patterns of delegation of concerns and leaves for itself only one task - recycling items.

How to animate RecyclerView items when they appear

I animated fading in of Recyclerview items when they first appear as shown in the code below. Perhaps this will be of use to someone.

private final static int FADE_DURATION = 1000; //FADE_DURATION in milliseconds

public void onBindViewHolder(ViewHolder holder, int position) {

    holder.getTextView().setText("some text");

    // Set the view to fade in

private void setFadeAnimation(View view) {
    AlphaAnimation anim = new AlphaAnimation(0.0f, 1.0f);

You can also replace setFadeAnimation() with the following setScaleAnimation() to animate appearance of items by scaling them from a point:

private void setScaleAnimation(View view) {
    ScaleAnimation anim = new ScaleAnimation(0.0f, 1.0f, 0.0f, 1.0f, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);

The code above has some warts in so far as when you scroll the RecyclerView items always fade or scale. If you wish you can add code to just allow the animation to happen when the fragment or activity containing the RecyclerView is first created (e.g. get the system time on creation and only allow animation for the first FADE_DURATION milliseconds).

Postman Chrome: What is the difference between form-data, x-www-form-urlencoded and raw

These are different Form content types defined by W3C. If you want to send simple text/ ASCII data, then x-www-form-urlencoded will work. This is the default.

But if you have to send non-ASCII text or large binary data, the form-data is for that.

You can use Raw if you want to send plain text or JSON or any other kind of string. Like the name suggests, Postman sends your raw string data as it is without modifications. The type of data that you are sending can be set by using the content-type header from the drop down.

Binary can be used when you want to attach non-textual data to the request, e.g. a video/audio file, images, or any other binary data file.

Refer to this link for further reading: Forms in HTML documents

How to recover the deleted files using "rm -R" command in linux server?

since answers are disappointing I would like suggest a way in which I got deleted stuff back.

I use an ide to code and accidently I used rm -rf from terminal to remove complete folder. Thanks to ide I recoved it back by reverting the change from ide's local history.

(my ide is intelliJ but all ide's support history backup)

Python IndentationError unindent does not match any outer indentation level

I recently ran into the same problem but the issue wasn't related to tabs and spaces but an odd Unicode character that appeared invisible to the eye in my IDE. Eventually, I isolated the problem and typed out the line exactly as it was and checked the git diff:

enter image description here

If you are able to isolate the line before the reported line and type it out again, you might find that it solves your problem. Won't tell you why it happened in the first place, but it at least gets rid of the issue.

Install IPA with iTunes 12

In my case Drag & Drop didn't work.

  1. I had to first Sync iTunes with the iOS device (Sync button on the bottom right)
  2. I had to add the IPA file through iTunes menu bar: File -> Add to Library...
  3. I had to press the "Install" button for my app in the "Apps" screen
  4. I had to press the "Apply" button on the bottom right

Swift: Sort array of objects alphabetically

With Swift 3, you can choose one of the following ways to solve your problem.

1. Using sorted(by:?) with a Movie class that does not conform to Comparable protocol

If your Movie class does not conform to Comparable protocol, you must specify in your closure the property on which you wish to use Array's sorted(by:?) method.

Movie class declaration:

import Foundation

class Movie: CustomStringConvertible {

    let name: String
    var date: Date
    var description: String { return name }

    init(name: String, date: Date = Date()) { = name = date



let avatarMovie = Movie(name: "Avatar")
let titanicMovie = Movie(name: "Titanic")
let piranhaMovie = Movie(name: "Piranha II: The Spawning")

let movies = [avatarMovie, titanicMovie, piranhaMovie]
let sortedMovies = movies.sorted(by: { $ < $ })
// let sortedMovies = movies.sorted { $ < $ } // also works


prints: [Avatar, Piranha II: The Spawning, Titanic]

2. Using sorted(by:?) with a Movie class that conforms to Comparable protocol

However, by making your Movie class conform to Comparable protocol, you can have a much concise code when you want to use Array's sorted(by:?) method.

Movie class declaration:

import Foundation

class Movie: CustomStringConvertible, Comparable {

    let name: String
    var date: Date
    var description: String { return name }

    init(name: String, date: Date = Date()) { = name = date

    static func ==(lhs: Movie, rhs: Movie) -> Bool {
        return ==

    static func <(lhs: Movie, rhs: Movie) -> Bool {
        return <



let avatarMovie = Movie(name: "Avatar")
let titanicMovie = Movie(name: "Titanic")
let piranhaMovie = Movie(name: "Piranha II: The Spawning")

let movies = [avatarMovie, titanicMovie, piranhaMovie]
let sortedMovies = movies.sorted(by: { $0 < $1 })
// let sortedMovies = movies.sorted { $0 < $1 } // also works
// let sortedMovies = movies.sorted(by: <) // also works


 prints: [Avatar, Piranha II: The Spawning, Titanic]

3. Using sorted() with a Movie class that conforms to Comparable protocol

By making your Movie class conform to Comparable protocol, you can use Array's sorted() method as an alternative to sorted(by:?).

Movie class declaration:

import Foundation

class Movie: CustomStringConvertible, Comparable {

    let name: String
    var date: Date
    var description: String { return name }

    init(name: String, date: Date = Date()) { = name = date

    static func ==(lhs: Movie, rhs: Movie) -> Bool {
        return ==

    static func <(lhs: Movie, rhs: Movie) -> Bool {
        return <



let avatarMovie = Movie(name: "Avatar")
let titanicMovie = Movie(name: "Titanic")
let piranhaMovie = Movie(name: "Piranha II: The Spawning")

let movies = [avatarMovie, titanicMovie, piranhaMovie]
let sortedMovies = movies.sorted()


 prints: [Avatar, Piranha II: The Spawning, Titanic]

How to edit nginx.conf to increase file size upload

You can increase client_max_body_size and upload_max_filesize + post_max_size all day long. Without adjusting HTTP timeout it will never work.

//You need to adjust this, and probably on PHP side also. client_body_timeout 2min // 1GB fileupload

Using array map to filter results with if conditional

You could use flatMap. It can filter and map in one.

$scope.appIds = $scope.applicationsHere.flatMap(obj => obj.selected ? : [])

Convert a Pandas DataFrame to a dictionary

df = pd.DataFrame([['p',1,3,2], ['q',4,3,2], ['r',4,0,9]], columns=['ID','A','B','C'])
my_dict = {k:list(v) for k,v in zip(df['ID'], df.drop(columns='ID').values)}

with output

{'p': [1, 3, 2], 'q': [4, 3, 2], 'r': [4, 0, 9]}

How to test the `Mosquitto` server?

If you wish to have an GUI based broker testing without installing any tool you can use Hive Mqtt web socket for testing your Mosquitto server

just visit and enter server connection details.

If you got connected means your server is configured properly.

You can also test publish and subscribe of messages using this mqtt web socket

How to change the color of a SwitchCompat from AppCompat library

So some days I lack brain cells and:


does not apply the theme because style is incorrect. I was supposed to use app:theme :P


Whoopsies. This post was what gave me insight into my mistake...hopefully if someone stumbles across this it will help them like it did me. Thank you Gaëtan Maisse for your answer

call javascript function onchange event of dropdown list

Your code is working just fine, you have to declare javscript method before DOM ready.

your working example

Adding an assets folder in Android Studio

According to new Gradle based build system. We have to put assets under main folder.

Or simply right click on your project and create it like

File > New > folder > assets Folder

How do I change UIView Size?

Hi create this extends if you want. Update 2021 Swift 5

Create File Extends.Swift and add this code (add import foundation where you want change height)

extension UIView {
    Get Set x Position
    - parameter x: CGFloat
    var x:CGFloat {
        get {
            return self.frame.origin.x
        set {
            self.frame.origin.x = newValue
    Get Set y Position
    - parameter y: CGFloat
    var y:CGFloat {
        get {
            return self.frame.origin.y
        set {
            self.frame.origin.y = newValue
    Get Set Height
    - parameter height: CGFloat
    var height:CGFloat {
        get {
            return self.frame.size.height
        set {
            self.frame.size.height = newValue
    Get Set Width
    - parameter width: CGFloat
    var width:CGFloat {
        get {
            return self.frame.size.width
        set {
            self.frame.size.width = newValue

For Use (inherits Of UIView)

inheritsOfUIView.height = 100
button.height = 100

how can I connect to a remote mongo server from Mac OS terminal

Another way to do this is:

mongo mongodb://mongoDbIPorDomain:port

Spring AMQP + RabbitMQ 3.3.5 ACCESS_REFUSED - Login was refused using authentication mechanism PLAIN

I was facing this issue due to empty space at the end of the password(spring.rabbitmq.password=rabbit ) in spring boot got resolved on removing the empty space. Hope this checklist helps some one facing this issue.

Add bottom line to view in SwiftUI / Swift / Objective-C / Xamarin

If you want to do without knowing frames beforehand, without subclassing and without Autolayout:

Swift 5 / Swift 4.x / Swift 3.x

extension UITextField {
  func setBottomBorder() {
    self.borderStyle = .none
    self.layer.backgroundColor = UIColor.white.cgColor

    self.layer.masksToBounds = false
    self.layer.shadowColor = UIColor.gray.cgColor
    self.layer.shadowOffset = CGSize(width: 0.0, height: 1.0)
    self.layer.shadowOpacity = 1.0
    self.layer.shadowRadius = 0.0

Call as yourTextField.setBottomBorder() from anywhere without making sure of the frames to be right.

The Result looks like this:


Swift UI

struct MyTextField: View {
  var myPlaceHolder: String
  @Binding var text: String

  var underColor: Color
  var height: CGFloat

  var body: some View {
    VStack {
        TextField(self.myPlaceHolder, text: $text)

        Rectangle().frame(height: self.height)
            .padding(.horizontal, 24).foregroundColor(self.underColor)

Does swift have a trim method on String?

Yes it has, you can do it like this:

var str = "  this is the answer   "
str = str.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
print(srt) // "this is the answer"

CharacterSet is actually a really powerful tool to create a trim rule with much more flexibility than a pre defined set like .whitespacesAndNewlines has.

For Example:

var str = " Hello World !"
let cs = CharacterSet.init(charactersIn: " !")
str = str.trimmingCharacters(in: cs)
print(str) // "Hello World"

Android Volley - BasicNetwork.performRequest: Unexpected response code 400

One way of doing this without changing Volley's source code is to check for the response data in the VolleyError and parse it your self.

As of f605da3 commit, Volley throws a ServerError exception that contains the raw network response.

So you can do something similar to this in your error listener:

/* import; */
public void onErrorResponse(VolleyError error) {

    // As of f605da3 the following should work
    NetworkResponse response = error.networkResponse;
    if (error instanceof ServerError && response != null) {
        try {
            String res = new String(,
                       HttpHeaderParser.parseCharset(response.headers, "utf-8"));
            // Now you can use any deserializer to make sense of data
            JSONObject obj = new JSONObject(res);
        } catch (UnsupportedEncodingException e1) {
            // Couldn't properly decode data to string
        } catch (JSONException e2) {
            // returned data is not JSONObject?

For future, if Volley changes, one can follow the above approach where you need to check the VolleyError for raw data that has been sent by the server and parse it.

I hope that they implement that TODO mentioned in the source file.

Failure [INSTALL_FAILED_UPDATE_INCOMPATIBLE] even if app appears to not be installed

Ok uninstall the app, but we admit that the data not must be lost? This can be resolve, upgrading versionCode and versionName and try the application in "Release" mode.

For example, this is important when we want to try the migration of our Database. We can compare the our application on play store with actual application not release yet.

Swift - Integer conversion to Hours/Minutes/Seconds

Answer of @r3dm4n was great. However, I needed also hour in it. Just in case someone else needed too here it is:

func formatSecondsToString(_ seconds: TimeInterval) -> String {
    if seconds.isNaN {
        return "00:00:00"
    let sec = Int(seconds.truncatingRemainder(dividingBy: 60))
    let min = Int(seconds.truncatingRemainder(dividingBy: 3600) / 60)
    let hour = Int(seconds / 3600)
    return String(format: "%02d:%02d:%02d", hour, min, sec)

Xcode "Device Locked" When iPhone is unlocked

These steps worked for me in iOS 10.

  1. Remove the cable from device.
  2. Plug in the device.
  3. Clean and build the Xcode project.

How to add "active" class to wp_nav_menu() current menu item (simple way)

Just paste this code into functions.php file:

add_filter('nav_menu_css_class' , 'special_nav_class' , 10 , 2);

function special_nav_class ($classes, $item) {
  if (in_array('current-menu-item', $classes) ){
    $classes[] = 'active ';
  return $classes;

More on

How to change color of the back arrow in the new material theme?

if use Toolbar,you can try this

Drawable drawable = toolbar.getNavigationIcon();
drawable.setColorFilter(ContextCompat.getColor(appCompatActivity, colorId), PorterDuff.Mode.SRC_ATOP);

Normalizing a list of numbers in Python

if your list has negative numbers, this is how you would normalize it

a = range(-30,31,5)
norm = [(float(i)-min(a))/(max(a)-min(a)) for i in a]

How to add buttons like refresh and search in ToolBar in Android?

To control the location of the title you may want to set a custom font as explained here (by twaddington): Link

Then to relocate the position of the text, in updateMeasureState() you would add p.baselineShift += (int) (p.ascent() * R); Similarly in updateDrawState() add tp.baselineShift += (int) (tp.ascent() * R); Where R is double between -1 and 1.

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 {

Change the @Secured name binding annotation created before to support roles:

@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:

public class ExampleResource {

    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

    @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:

public class AuthorizationFilter implements ContainerRequestFilter {

    private ResourceInfo resourceInfo;

    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()) {
            } else {

        } catch (Exception e) {

    // 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:

public class AuthorizationFilter implements ContainerRequestFilter {

    private ResourceInfo resourceInfo;

    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)) {

        // @RolesAllowed on the method takes precedence over @PermitAll
        RolesAllowed rolesAllowed = method.getAnnotation(RolesAllowed.class);
        if (rolesAllowed != null) {
            performAuthorization(rolesAllowed.value(), requestContext);

        // @PermitAll on the method takes precedence over @RolesAllowed on the class
        if (method.isAnnotationPresent(PermitAll.class)) {
            // Do nothing

        // @DenyAll can't be attached to classes

        // @RolesAllowed on the class takes precedence over @PermitAll on the class
        rolesAllowed = 
        if (rolesAllowed != null) {
            performAuthorization(rolesAllowed.value(), requestContext);

        // @PermitAll on the class
        if (resourceInfo.getResourceClass().isAnnotationPresent(PermitAll.class)) {
            // Do nothing

        // Authentication is required for non-annotated methods
        if (!isAuthenticated(requestContext)) {

     * Perform authorization based on roles.
     * @param rolesAllowed
     * @param requestContext
    private void performAuthorization(String[] rolesAllowed, 
                                      ContainerRequestContext requestContext) {

        if (rolesAllowed.length > 0 && !isAuthenticated(requestContext)) {

        for (final String role : rolesAllowed) {
            if (requestContext.getSecurityContext().isUserInRole(role)) {


     * 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.

Can you get the number of lines of code from a GitHub repository?

Pipe the output from the number of lines in each file to sort to organize files by line count. git ls-files | xargs wc -l |sort -n

Spring-Security-Oauth2: Full authentication is required to access this resource

The client_id and client_secret, by default, should go in the Authorization header, not the form-urlencoded body.

  1. Concatenate your client_id and client_secret, with a colon between them: [email protected]:12345678.
  2. Base 64 encode the result: YWJjQGdtYWlsLmNvbToxMjM0NTY3OA==
  3. Set the Authorization header: Authorization: Basic YWJjQGdtYWlsLmNvbToxMjM0NTY3OA==

Split String by delimiter position using oracle SQL

Therefore, I would like to separate the string by the furthest delimiter.

I know this is an old question, but this is a simple requirement for which SUBSTR and INSTR would suffice. REGEXP are still slower and CPU intensive operations than the old subtsr and instr functions.

  2    ( SELECT 'F/P/O' str FROM dual
  3    )
  4  SELECT SUBSTR(str, 1, Instr(str, '/', -1, 1) -1) part1,
  5         SUBSTR(str, Instr(str, '/', -1, 1) +1) part2
  7  /

----- -----
F/P   O

As you said you want the furthest delimiter, it would mean the first delimiter from the reverse.

You approach was fine, but you were missing the start_position in INSTR. If the start_position is negative, the INSTR function counts back start_position number of characters from the end of string and then searches towards the beginning of string.

Scroll RecyclerView to show selected item on top

If you looking for vertical LinearLayout Manager you can achieve smooth scrolling using a custom LinearSmoothScroller:

import android.content.Context;

public class SnappingLinearLayoutManager extends LinearLayoutManager {

    public SnappingLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);

    public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state,
                                       int position) {
        RecyclerView.SmoothScroller smoothScroller = new TopSnappedSmoothScroller(recyclerView.getContext());

    private class TopSnappedSmoothScroller extends LinearSmoothScroller {
        public TopSnappedSmoothScroller(Context context) {


        public PointF computeScrollVectorForPosition(int targetPosition) {
            return SnappingLinearLayoutManager.this

        protected int getVerticalSnapPreference() {
            return SNAP_TO_START;

use an instance of the layoutmanager in recycle view and then calling recyclerView.smoothScrollToPosition(pos); will smooth scroll to selected position to top of the recycler view

MomentJS getting JavaScript Date in UTC

A timestamp is a point in time. Typically this can be represented by a number of milliseconds past an epoc (the Unix Epoc of Jan 1 1970 12AM UTC). The format of that point in time depends on the time zone. While it is the same point in time, the "hours value" is not the same among time zones and one must take into account the offset from the UTC.

Here's some code to illustrate. A point is time is captured in three different ways.

var moment = require( 'moment' );

var localDate = new Date();
var localMoment = moment();
var utcMoment = moment.utc();
var utcDate = new Date( utcMoment.format() );

//These are all the same
console.log( 'localData unix = ' + localDate.valueOf() );
console.log( 'localMoment unix = ' + localMoment.valueOf() );
console.log( 'utcMoment unix = ' + utcMoment.valueOf() );

//These formats are different
console.log( 'localDate = ' + localDate );
console.log( 'localMoment string = ' + localMoment.format() );
console.log( 'utcMoment string = ' + utcMoment.format() );
console.log( 'utcDate  = ' + utcDate );

//One to show conversion
console.log( 'localDate as UTC format = ' + moment.utc( localDate ).format() );
console.log( 'localDate as UTC unix = ' + moment.utc( localDate ).valueOf() );

Which outputs this:

localData unix = 1415806206570
localMoment unix = 1415806206570
utcMoment unix = 1415806206570
localDate = Wed Nov 12 2014 10:30:06 GMT-0500 (EST)
localMoment string = 2014-11-12T10:30:06-05:00
utcMoment string = 2014-11-12T15:30:06+00:00
utcDate  = Wed Nov 12 2014 10:30:06 GMT-0500 (EST)
localDate as UTC format = 2014-11-12T15:30:06+00:00
localDate as UTC unix = 1415806206570

In terms of milliseconds, each are the same. It is the exact same point in time (though in some runs, the later millisecond is one higher).

As far as format, each can be represented in a particular timezone. And the formatting of that timezone'd string looks different, for the exact same point in time!

Are you going to compare these time values? Just convert to milliseconds. One value of milliseconds is always less than, equal to or greater than another millisecond value.

Do you want to compare specific 'hour' or 'day' values and worried they "came from" different timezones? Convert to UTC first using moment.utc( existingDate ), and then do operations. Examples of those conversions, when coming out of the DB, are the last console.log calls in the example.

Show DataFrame as table in iPython Notebook

It seems you can just display both dfs using a comma in between in display. I noticed this on some notebooks on github. This code is from Jake VanderPlas's notebook.

class display(object):
    """Display HTML representation of multiple objects"""
    template = """<div style="float: left; padding: 10px;">
    <p style='font-family:"Courier New", Courier, monospace'>{0}</p>{1}
    def __init__(self, *args):
        self.args = args

    def _repr_html_(self):
        return '\n'.join(self.template.format(a, eval(a)._repr_html_())
                     for a in self.args)

    def __repr__(self):
        return '\n\n'.join(a + '\n' + repr(eval(a))
                       for a in self.args)

display('df', "df2")

print highest value in dict with key

You could use use max and min with dict.get:

maximum = max(mydict, key=mydict.get)  # Just use 'min' instead of 'max' for minimum.
print(maximum, mydict[maximum])
# D 87

What is the difference between cache and persist?

For impatient:


Without passing argument, persist() and cache() are the same, with default settings:

  • when Dataset: MEMORY_AND_DISK


Unlike cache(), persist() allows you to pass argument inside the bracket, in order to specify the level:

  • persist(MEMORY_ONLY)
  • persist(MEMORY_ONLY_SER)
  • persist(MEMORY_AND_DISK)
  • persist(MEMORY_AND_DISK_SER )
  • persist(DISK_ONLY )


Font awesome is not showing icon

my issue was the one having most of the votes

font-family: xxxxx

changing it to this solved the problem

font-family: xxxx

mysql-python install error: Cannot open include file 'config-win.h'

For mysql8 and python 3.7 on windows, I find previous solutions seems not work for me.

Here is what worked for me:

pip install wheel

pip install mysqlclient-1.4.2-cp37-cp37m-win_amd64.whl

python -m pip install mysql-connector-python

python -m pip install SQLAlchemy


"The system cannot find the file C:\ProgramData\Oracle\Java\javapath\java.exe"

If you're on a corporate PC that's fairly restricted by group policy, this might work....

Assuming that

  1. your Windows PATH includes C:\ProgramData\Oracle\Java\javapath
  2. you have JDK installed to C:\Program Files\Java\jdk1.8.0_60\bin

Then create the following text file mklink.bat and put it on your desktop:

rem mklink.bat
mklink /d C:\ProgramData\Oracle\Java\javapath "C:\Program Files\Java\jdk1.8.0_60\bin"

Now right-click it and choose "Run as Administrator". Provide admin credentials. The script should report success. Now you can compile or run Java.

How to reset the bootstrap modal when it gets closed and open it fresh again?

Reset form inside the modal. Sample Code:

$('#myModal').on('', '#myModal', function (e) {
    $('#myModal form')[0].reset();

How to set portrait and landscape media queries in css?

It can also be as simple as this.

@media (orientation: landscape) {


ORA-28000: the account is locked error getting frequently

Solution 01

Account Unlock by using below query :

SQL> select USERNAME,ACCOUNT_STATUS from dba_users where username='ABCD_DEV';    
-------------------- --------------------------------

SQL> alter user ABCD_DEV account unlock;    
User altered.

SQL> select USERNAME,ACCOUNT_STATUS from dba_users where username='ABCD_DEV';    
-------------------- --------------------------------

Solution 02

Check PASSWORD_LIFE_TIME parameter by using below query :

SELECT resource_name, limit FROM dba_profiles WHERE profile = 'DEFAULT' AND resource_type = 'PASSWORD';

RESOURCE_NAME                    LIMIT
-------------------------------- ------------------------------
PASSWORD_LIFE_TIME               10
PASSWORD_REUSE_TIME              10
PASSWORD_LOCK_TIME               1
PASSWORD_GRACE_TIME              7

Change the parameter using below query


How to automatically import data from uploaded CSV or XLS file into Google Sheets

(Mar 2017) The accepted answer is not the best solution. It relies on manual translation using Apps Script, and the code may not be resilient, requiring maintenance. If your legacy system autogenerates CSV files, it's best they go into another folder for temporary processing (importing [uploading to Google Drive & converting] to Google Sheets files).

My thought is to let the Drive API do all the heavy-lifting. The Google Drive API team released v3 at the end of 2015, and in that release, insert() changed names to create() so as to better reflect the file operation. There's also no more convert flag -- you just specify MIMEtypes... imagine that!

The documentation has also been improved: there's now a special guide devoted to uploads (simple, multipart, and resumable) that comes with sample code in Java, Python, PHP, C#/.NET, Ruby, JavaScript/Node.js, and iOS/Obj-C that imports CSV files into Google Sheets format as desired.

Below is one alternate Python solution for short files ("simple upload") where you don't need the apiclient.http.MediaFileUpload class. This snippet assumes your auth code works where your service endpoint is DRIVE with a minimum auth scope of

# filenames & MIMEtypes
DST_FILENAME = 'inventory'
SHT_MIMETYPE = 'application/'
CSV_MIMETYPE = 'text/csv'

# Import CSV file to Google Drive as a Google Sheets file
rsp = DRIVE.files().create(body=METADATA, media_body=SRC_FILENAME).execute()
if rsp:
    print('Imported %r to %r (as %s)' % (SRC_FILENAME, DST_FILENAME, rsp['mimeType']))

Better yet, rather than uploading to My Drive, you'd upload to one (or more) specific folder(s), meaning you'd add the parent folder ID(s) to METADATA. (Also see the code sample on this page.) Finally, there's no native .gsheet "file" -- that file just has a link to the online Sheet, so what's above is what you want to do.

If not using Python, you can use the snippet above as pseudocode to port to your system language. Regardless, there's much less code to maintain because there's no CSV parsing. The only thing remaining is to blow away the CSV file temp folder your legacy system wrote to.

sudo service mongodb restart gives "unrecognized service error" in ubuntu 14.0.4

I installed mongo server on Debian Jessie using manual from official site.

It didn't started after recommended command sudo service mongod restart with the same error - mongodb: unrecognized service.

After looking into installed package contents, I noticed that it contains only Systemd service unit, but no SystemV init script:

# dpkg -L mongodb-org-server

But my system was running on SysV init:

# stat /proc/1/exe
File: '/proc/1/exe' -> '/sbin/init'

So, there are 2 options now:

SMTPAuthenticationError when sending mail using gmail and python

I have just sent an email with gmail through Python. Try to use smtplib.SMTP_SSL to make the connection. Also, you may try to change the gmail domain and port.

So, you may get a chance with:

server = smtplib.SMTP_SSL('', 465)
server.login(gmail_user, password)
server.sendmail(gmail_user, TO, BODY)

As a plus, you could check the email builtin module. In this way, you can improve the readability of you your code and handle emails headers easily.

How do you set the title color for the new Toolbar?

Option 1) The quick and easy way (Toolbar only)

Since appcompat-v7-r23 you can use the following attributes directly on your Toolbar or its style:


If your minimum SDK is 23 and you use native Toolbar just change the namespace prefix to android.

In Java you can use the following methods:


These methods take a color int not a color resource ID!

Option 2) Override Toolbar style and theme attributes




<style name="Widget.MyApp.Toolbar.Solid" parent="Widget.AppCompat.ActionBar">
    <item name="android:background">@color/actionbar_color</item>
    <item name="android:elevation" tools:ignore="NewApi">4dp</item>
    <item name="titleTextAppearance">...</item>

<style name="ThemeOverlay.MyApp.ActionBar" parent="ThemeOverlay.AppCompat.ActionBar">
    <!-- Parent theme sets colorControlNormal to textColorPrimary. -->
    <item name="android:textColorPrimary">@color/actionbar_title_text</item>

Help! My icons changed color too!

@PeterKnut reported this affects the color of overflow button, navigation drawer button and back button. It also changes text color of SearchView.

Concerning the icon colors: The colorControlNormal inherits from

  • android:textColorPrimary for dark themes (white on black)
  • android:textColorSecondary for light themes (black on white)

If you apply this to the action bar's theme, you can customize the icon color.

<item name="colorControlNormal">#de000000</item>

There was a bug in appcompat-v7 up to r23 which required you to also override the native counterpart like so:

<item name="android:colorControlNormal" tools:ignore="NewApi">?colorControlNormal</item>

Help! My SearchView is a mess!

Note: This section is possibly obsolete.

Since you use the search widget which for some reason uses different back arrow (not visually, technically) than the one included with appcompat-v7, you have to set it manually in the app's theme. Support library's drawables get tinted correctly. Otherwise it would be always white.

<item name="homeAsUpIndicator">@drawable/abc_ic_ab_back_mtrl_am_alpha</item>

As for the search view text...there's no easy way. After digging through its source I found a way to get to the text view. I haven't tested this so please let me know in the comments if this didn't work.

SearchView sv = ...; // get your search view instance in onCreateOptionsMenu
// prefix identifier with "android:" if you're using native SearchView
TextView tv = sv.findViewById(getResources().getIdentifier("id/search_src_text", null, null));
tv.setTextColor(Color.GREEN); // and of course specify your own color

Bonus: Override ActionBar style and theme attributes

Appropriate styling for a default action appcompat-v7 action bar would look like this:

<!-- ActionBar vs Toolbar. -->
<style name="Widget.MyApp.ActionBar.Solid" parent="Widget.AppCompat.ActionBar.Solid">
    <item name="background">@color/actionbar_color</item> <!-- No prefix. -->
    <item name="elevation">4dp</item> <!-- No prefix. -->
    <item name="titleTextStyle">...</item> <!-- Style vs appearance. -->

<style name="Theme.MyApp" parent="Theme.AppCompat">
    <item name="actionBarStyle">@style/Widget.MyApp.ActionBar.Solid</item>
    <item name="actionBarTheme">@style/ThemeOverlay.MyApp.ActionBar</item>
    <item name="actionBarPopupTheme">@style/ThemeOverlay.AppCompat.Light</item>

Converting list to numpy array

If you have a list of lists, you only needed to use ...

import numpy as np
npa = np.asarray(someListOfLists, dtype=np.float32)

per this LINK in the scipy / numpy documentation. You just needed to define dtype inside the call to asarray.

Swift convert unix time to date and time

For managing dates in Swift 3 I ended up with this helper function:

extension Double {
    func getDateStringFromUTC() -> String {
        let date = Date(timeIntervalSince1970: self)

        let dateFormatter = DateFormatter()
        dateFormatter.locale = Locale(identifier: "en_US")
        dateFormatter.dateStyle = .medium

        return dateFormatter.string(from: date)

This way it easy to use whenever you need it - in my case it was converting a string:

("1481721300" as! Double).getDateStringFromUTC() // "Dec 14, 2016"

Reference the DateFormatter docs for more details on formatting (Note that some of the examples are out of date)

I found this article to be very helpful as well

Javascript querySelector vs. getElementById

The functions getElementById and getElementsByClassName are very specific, while querySelector and querySelectorAll are more elaborate. My guess is that they will actually have a worse performance.

Also, you need to check for the support of each function in the browsers you are targetting. The newer it is, the higher probability of lack of support or the function being "buggy".

Printing column separated by comma using Awk command line


awk -F',' '{print $3}' myfile.txt

Here in -F you are saying to awk that use "," as field separator.

sweet-alert display HTML code in text

I assume that </ is not accepted inside the string.

Try to escape the forward slash "/" by preceding it with a backward slash "\" for example:

var hh = "<b>test<\/b>";

Pandas Replace NaN with blank/empty string

I tried with one column of string values with nan.

To remove the nan and fill the empty string:

df.columnname.replace(np.nan,'',regex = True)

To remove the nan and fill some values:

df.columnname.replace(np.nan,'value',regex = True)

I tried df.iloc also. but it needs the index of the column. so you need to look into the table again. simply the above method reduced one step.

How to change UIButton image in Swift

you can actually do this by highlighting the button and within the insepctor on the right hand tool bar you can update the image. obviously you can do it in code also as stated previously but this is another option for you

Change tab bar item selected color in a storyboard

This elegant solution works great on SWIFT 3.0, SWIFT 4.2 and SWIFT 5.1:

On the Storyboard:

  1. Select your Tab Bar
  2. Set a Runtime Attibute called tintColor for the desired color of the Selected Icon on the tab bar
  3. Set a Runtime Attibute called unselectedItemTintColor for the desired color of the Unselected Icon on the tab bar

enter image description here

Edit: Working with Xcode 8/10, for iOS 10/12 and above.

ImportError: No module named enum

Or run a pip install --upgrade pip enum34

Extract Number from String in Python

a = []
line = "abcd 3455 ijkl 56.78 ij"
for word in line.split():
  except ValueError:


3455.0 56.78

Return HTML from ASP.NET Web API

Starting with AspNetCore 2.0, it's recommended to use ContentResult instead of the Produce attribute in this case. See:

This doesn't rely on serialization nor on content negotiation.

public ContentResult Index() {
    return new ContentResult {
        ContentType = "text/html",
        StatusCode = (int)HttpStatusCode.OK,
        Content = "<html><body>Hello World</body></html>"

How to implement a material design circular progress bar in android

The platform uses a vector drawable, so you can't reuse it as in in older versions.
However, the support lib v4 contains a backport of this drawable : It has a @hide annotation (it is here for the SwipeRefreshLayout), but nothing prevents you from copying this class in your codebase.

Want to make Font Awesome icons clickable

I found this worked best for my usecase:

<i class="btn btn-light fa fa-dribbble fa-4x" href="#"></i>
<i class="btn btn-light fa fa-behance-square fa-4x" href="#"></i>
<i class="btn btn-light fa fa-linkedin-square fa-4x" href="#"></i>
<i class="btn btn-light fa fa-twitter-square fa-4x" href="#"></i>
<i class="btn btn-light fa fa-facebook-square fa-4x" href="#"></i>

Typescript: How to extend two classes?

I would suggest using the new mixins approach described there:

This approach is better, than the "applyMixins" approach described by Fenton, because the autocompiler would help you and show all the methods / properties from the both base and 2nd inheritance classes.

This approach might be checked on the TS Playground site.

Here is the implementation:

class MainClass {
    testMainClass() {

const addSecondInheritance = (BaseClass: { new(...args) }) => {
    return class extends BaseClass {
        testSecondInheritance() {

// Prepare the new class, which "inherits" 2 classes (MainClass and the cass declared in the addSecondInheritance method)
const SecondInheritanceClass = addSecondInheritance(MainClass);
// Create object from the new prepared class
const secondInheritanceObj = new SecondInheritanceClass();

Pure Javascript listen to input value change

Another approach in 2020 could be using document.querySelector():

const myInput = document.querySelector('input[name="exampleInput"]');

myInput.addEventListener("change", (e) => {
  // here we do something