Tutorial by Examples: d

Including LaTeX Preample Commands

There are two possible ways of including LaTeX preamble commands (e.g. \usepackage) in a RMarkdown document. 1. Using the YAML option header-includes: --- title: "Including LaTeX Preample Commands in RMarkdown" header-includes: - \renewcommand{\familydefault}{cmss} - \usepacka...

R Language • Creating reports with RMarkdown

Including bibliographies

A bibtex catalogue cna easily be included with the YAML option bibliography:. A certain style for the bibliography can be added with biblio-style:. The references are added at the end of the document. --- title: "Including Bibliography" author: "John Doe" output: pdf_documen...

R Language • Creating reports with RMarkdown

Parsing JavaScript Generated Page with Jsoup and HtmUnit

page.html - source code <html> <head> <script src="loadData.js"></script> </head> <body onLoad="loadData()"> <div class="container"> <table id="data" border="1"> <...

Jsoup • Parsing Javascript Generated Pages

Using the default Form instance

VB.NET offers default Form instances. The developer does not need to create the instance as it is created behind the scenes. However, it is not preferable to use the default instance all but the simplest programs. Public Class Form1 Public Sub Foo() MessageBox.Show("Bar") ...

Visual Basic .NET Language • Working with Windows Forms

Installing nginx and setting it up for uWSGI

Now we want to install nginx to serve our application. sudo apt-get install nginx # on debian/ubuntu Then we create a configuration for our website cd /etc/nginx/site-available # go to the configuration for available sites # create a file flaskconfig with your favourite editor flaskconfig...

Flask • Deploying Flask application using uWSGI web server with Nginx

CRTP to avoid code duplication

The example in Visitor Pattern provides a compelling use-case for CRTP: struct IShape { virtual ~IShape() = default; virtual void accept(IShapeVisitor&) const = 0; }; struct Circle : IShape { // ... // Each shape has to implement this method the same way ...

C++ • Curiously Recurring Template Pattern (CRTP)

Creating zip archive from directory

System.IO.Compression.ZipFile.CreateFromDirectory("myfolder", "archive.zip") Create archive.zip file containing files which are in myfolder. In example paths are relative to program working directory. You can specify absolute paths.

Visual Basic .NET Language • File/Folder Compression

Extracting zip archive to directory

System.IO.Compression.ZipFile.ExtractToDirectory("archive.zip", "myfolder") Extracts archive.zip to myfolder directory. In example paths are relative to program working directory. You can specify absolute paths.

Visual Basic .NET Language • File/Folder Compression

Create zip archive dynamicaly

' Create filestream to file Using fileStream = New IO.FileStream("archive.zip", IO.FileMode.Create) ' open zip archive from stream Using archive = New System.IO.Compression.ZipArchive(fileStream, IO.Compression.ZipArchiveMode.Create) ' create file_in_archive.txt in arch...

Visual Basic .NET Language • File/Folder Compression

Reads file (/etc/passwd) line by line and field by field

#!/bin/bash FILENAME="/etc/passwd" while IFS=: read -r username password userid groupid comment homedir cmdshell do echo "$username, $userid, $comment $homedir" done < $FILENAME In unix password file, user information is stored line by line, each line consisting of i...

Bash • Read a file (data stream, variable) line-by-line (and/or field-by-field)?

How to compose values and functions using common operators

In Object Oriented Programming a common task is to compose objects (values). In Functional Programming it is as common task to compose values as well as functions. We are used to compose values from our experience of other programming languages using operators like +, -, *, / and so on. Value co...

F# • Operators

Latebinding in F# using ? operator

In a statically typed language like F# we work with types well-known at compile-time. We consume external data sources in a type-safe manner using type providers. However, occassionally there's need to use late binding (like dynamic in C#). For instance when working with JSON documents that have...

F# • Operators

Adding a UIRefreshControl to a TableView

Assumptions: TableView - reference to the TableView DataSource - is a class which inherits UITableViewSource DataSource.Objects - is a public List< object >(), accessible to the UIViewController private UIRefreshControl refreshControl; public override void ViewDidLoad() { base.V...

Xamarin.iOS • Adding UIRefreshControl to a table view

Dictionaries are unordered

You might expect a Python dictionary to be sorted by keys like, for example, a C++ std::map, but this is not the case: myDict = {'first': 1, 'second': 2, 'third': 3} print(myDict) # Out: {'first': 1, 'second': 2, 'third': 3} print([k for k in myDict]) # Out: ['second', 'third', 'first'] Py...

Python Language • Common Pitfalls

RecordWildCards

See RecordWildCards

Haskell Language • Common GHC Language Extensions

POSIX Timer with SIGEV_THREAD notification

This example demonstrates POSIX Timer usage with CLOCK_REALTIME clock and SIGEV_THREAD notification method. #include <stdio.h> /* for puts() */ #include <string.h> /* for memset() */ #include <unistd.h> /* for sleep() */ #include <stdlib.h> /* for EXIT_SUCCESS */ #inc...

POSIX • Timers

Detecting when UIScrollView finished scrolling with delegate methods

scrollViewDidEndDecelerating: this tells the delegate that the scroll view has ended decelerating the scrolling movement. Objective C: - (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView { [self stoppedScrolling]; } - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView w...

iOS • UIScrollView

Basic Model

This example shows how to define a simple model in Sails.js You can generate an empty model file by typing sails generate model car You'll find the new file Car.js in api/models/. Next, you fill in some details. modules.exports = { tableName : 'cars', connection : 'mongodb', attr...

sails.js • Models

SQLiteOpenHelper with fully qualified DB path name/databse in public folder

Normally Android-SQLiteOpenHelper does not allow fully qualified path names where the database should be stored. So public database files are not possible. You can use the SQLiteOpenHelper with a custom path if you provide a custom ContextClass and if you have write access in the target directory. ...

android-sqlite • SQLiteOpenHelper

UTC Time offset from NSDate with TimeZone

Here this will calculate the UTC time offset from current data in desired timezone. +(NSTimeInterval)getUTCOffSetIntervalWithCurrentTimeZone:(NSTimeZone *)current forDate:(NSDate *)date { NSTimeZone *utcTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"UTC"]; NSInteger currentG...

iOS • NSDate