Tutorial by Examples: al

Individual characters of strings are not assignable

foo = "bar" foo[0] = "c" # Error Immutable variable value can not be changed once they are created.

Python Language • Immutable datatypes(int, float, str, tuple and frozensets)

Tuple's individual members aren't assignable

foo = ("bar", 1, "Hello!",) foo[1] = 2 # ERROR!! Second line would return an error since tuple members once created aren't assignable. Because of tuple's immutability.

Python Language • Immutable datatypes(int, float, str, tuple and frozensets)

Installing on Linux

On Debian or Ubuntu, you can install SCons using $ sudo apt-get install scons On YUM-based systems, use $ sudo yum install scons You can install using an RPM by downloading it, then running $ sudo rpm -Uvh http://prdownloads.sourceforge.net/scons/scons-2.5.0-1.noarch.rpm

SCons • Getting SCons running

Named arguments and optional paramaters

You can combine named arguments with optional parameters. Let see this method: public sealed class SmsUtil { public static bool SendMessage(string from, string to, string message, int retryCount = 5, object attachment = null) { // Some code } } When you want to call t...

C# Language • Named Arguments

Examples from the official documentation

stats::heatmap Example 1 (Basic usage) require(graphics); require(grDevices) x <- as.matrix(mtcars) rc <- rainbow(nrow(x), start = 0, end = .3) cc <- rainbow(ncol(x), start = 0, end = .3) hv <- heatmap(x, col = cm.colors(256), scale = "column", RowSideColo...

R Language • heatmap and heatmap.2

mcparallelDo

The mcparallelDo package allows for the evaluation of R code asynchronously on Unix-alike (e.g. Linux and MacOSX) operating systems. The underlying philosophy of the package is aligned with the needs of exploratory data analysis rather than coding. For coding asynchrony, consider the future packag...

R Language • Parallel processing

DecimalPropertyConvention

By default Entity Framework maps decimal properties to decimal(18,2) columns in database tables. public class Box { public int Id { set; get; } public decimal Length { set; get; } public decimal Width { set; get; } public decimal Height { set; get; } } We can change the p...

Entity Framework • Code First Conventions

Deleting a derived object via a pointer to a base class that doesn't have a virtual destructor.

class base { }; class derived: public base { }; int main() { base* p = new derived(); delete p; // The is undefined behavior! } In section [expr.delete] §5.3.5/3 the standard says that if delete is called on an object whose static type does not have a virtual destructor: if the...

C++ • Undefined Behavior

Animate at a specified interval (add a new rectangle every 1 second)

This example adds a new rectangle to the canvas every 1 second (== a 1 second interval) Annotated Code: <!doctype html> <html> <head> <style> body{ background-color:white; } #canvas{border:1px solid red; } </style> <script> window.onload=(functio...

html5-canvas • Animation

Use requestAnimationFrame() NOT setInterval() for animation loops

requestAnimationFrame is similar to setInterval, it but has these important improvements: The animation code is synchronized with display refreshes for efficiency The clear + redraw code is scheduled, but not immediately executed. The browser will execute the clear + redraw code only when the d...

html5-canvas • Animation

Installation or Setup

Detailed instructions on getting netty set up or installed.

netty • Getting started with netty

Dialects of Lisp and their implementations

Invented by John McCarthy around 1958, Lisp (List Processor) has continued to grow into an entire family of languages. Since StackOverflow is more about practical programming problems, typically problems will involve actual Lisp dialects or derived languages and their implementations. Problems that...

lisp • Getting started with lisp

Testing all commits during rebase

Before making a pull request, it is useful to make sure that compile is successful and tests are passing for each commit in the branch. We can do that automatically using -x parameter. For example: git rebase -i -x make will perform the interactive rebase and stop after each commit to execute mak...

Git • Rebasing

Creating a bidirectional LSTM

import tensorflow as tf dims, layers = 32, 2 # Creating the forward and backwards cells lstm_fw_cell = tf.nn.rnn_cell.BasicLSTMCell(dims, forget_bias=1.0) lstm_bw_cell = tf.nn.rnn_cell.BasicLSTMCell(dims, forget_bias=1.0) # Pass lstm_fw_cell / lstm_bw_cell directly to tf.nn.bidrectional_rnn ...

tensorflow • Creating RNN, LSTM and bidirectional RNN/LSTMs with TensorFlow

Creating a custom analyzer

Most analysis customization is in the createComponents class, where the Tokenizer and TokenFilters are defined. CharFilters can be added in the initReader method. Analyzer analyzer = new Analyzer() { @Override protected Reader initReader(String fieldName, Reader reader) { retu...

lucene • Analysis

Iterating manually through analyzed tokens

TokenStream stream = myAnalyzer.tokenStream("myField", textToAnalyze); stream.addAttribute(CharTermAttribute.class); stream.reset(); while(stream.incrementToken()) { CharTermAttribute token = stream.getAttribute(CharTermAttribute.class); System.out.println(token.toString()); ...

lucene • Analysis

Default value of nullable types is null

public class NullableTypesExample { static int? _testValue; public static void Main() { if(_testValue == null) Console.WriteLine("null"); else Console.WriteLine(_testValue.ToString()); } } Output: null

C# Language • Nullable types

Assigning an out-of-range value to an integer

// Supposing SCHAR_MAX, the maximum value that can be represented by a signed char, is // 127, the behavior of this assignment is implementation-defined: signed char integer; integer = 128;

C Language • Implementation-defined behaviour

Allocating zero bytes

// The allocation functions have implementation-defined behavior when the requested size // of the allocation is zero. void *p = malloc(0);

C Language • Implementation-defined behaviour

Hello, World! (minimal)

Let's test our basic knowledge of tkinter by creating the classic "Hello, World!" program. First, we must import tkinter, this will vary based on version (see remarks section about "Differences between Python 2 and 3") In Python 3 the module tkinter has a lowercase t: import t...

tkinter • Getting started with tkinter