Tutorial by Examples: s

In order to check whether a value is NaN, isnull() or notnull() functions can be used. In [1]: import numpy as np In [2]: import pandas as pd In [3]: ser = pd.Series([1, 2, np.nan, 4]) In [4]: pd.isnull(ser) Out[4]: 0 False 1 False 2 True 3 False dtype: bool Note that n...

The following command imports CSV files into a MySQL table with the same columns while respecting CSV quoting and escaping rules. load data infile '/tmp/file.csv' into table my_table fields terminated by ',' optionally enclosed by '"' escaped by '"' lines terminated by '\n' ignore 1...

Installing the haystack package pip install django-haystack Configuration Add haystack to your project's INSTALLED_APPS inside of your settings.py file: # settings.py INSTALLED_APPS = [ 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', # Put...

Create custom class for calling multipart/form-data HttpURLConnection request MultipartUtility.java public class MultipartUtility { private final String boundary; private static final String LINE_FEED = "\r\n"; private HttpURLConnection httpConn; priva...

The option -v followed by an assignment of the form variable=value can be used to pass parameters to an awk program. This is illustrated by the punishment program below, whose job is to write count times the sentence “I shall not talk in class.” on standard output. The following example uses the v...

The awk language does not directly support variables local to functions. It is however easy emulate them by adding extra arguments to functions. It is traditional to prefix these variables by a _ to indicate that they are not actual parameters. We illustrate this technique with the definition of a...

ng-model-options allows to change the default behavior of ng-model, this directive allows to register events that will fire when the ng-model is updated and to attach a debounce effect. This directive accepts an expression that will evaluate to a definition object or a reference to a scope value. ...

// Returns the nth number in the Fibonacci sequence function fibonacci(n) { if (n === 1 || n === 0) { return 1; } else { return fibonacci(n - 1) + fibonacci(n - 2); } }

// Checks a string to see if it is a palindrome bool function IsPalindrome(string input) { if (input.size() <= 1) { return true; } else if (input[0] == input[input.size() - 1]) { return IsPalindrome(input.substr(1,input.size() - 2)); } else { r...

Custom events usually need custom event arguments containing information about the event. For example MouseEventArgs which is used by mouse events like MouseDown or MouseUp events, contains information about Location or Buttons which used to generate the event. When creating new events, to create a...

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Functions in Racket can be created with the lambda form. The form takes a list of arguments and a body. (lambda (x y) (* x y)) In the example above, the function takes in two arguments and returns the result of multiplying them. > ((lambda (x y) (* x y)) 4 4) 16 > ((lambda (x y) (* x y)...

Download and install Visual Studio Community 2015 Open Visual Studio Community Click File -> New -> Project Click Templates -> Visual C++ -> Win32 Console Application and then name the project MyFirstProgram. Click Ok Click Next in the following window. Check the Empty proj...

Each Error object has a string property named stack that contains the stack trace:

Instrument your code with console.trace() calls that print current JavaScript call stacks:

Place assertions in your JavaScript code by calling console.assert() with the error condition as the first parameter. When this expression evaluates to false, you will see a corresponding console record:

In many instances, you will want to send data from the R server to the JS client. Here is a very simple example: library(shiny) runApp( list( ui = fluidPage( tags$script( "Shiny.addCustomMessageHandler('message', function(params) { alert(params); });" ), ...

Modern browsers provide a classList object to ease manipulation of the element's class attribute. Older browsers require direct manipulation of the element's className property. W3C DOM4 A simple method to add a class to an element is to append it to the end of the className property. This will no...

Thread.sleep causes the current thread to suspend execution for a specified period. This is an efficient means of making processor time available to the other threads of an application or other applications that might be running on a computer system. There are two overloaded sleep methods in the Thr...