Tutorial by Examples: d

int[string] wordCount(string[] wordList) { int[string] words; foreach (word; wordList) { words[word]++; } return words; } void main() { int[string] count = wordCount(["hello", "world", "I", "say", "hello"]); ...

Reducing a list to a single value is easy when you have _.reduce. Let's say we wanted to see if a group of people could afford a cab ride. We'd want to look at all the money they have together as a group, which means we'd want to reduce a list of objects to a single value, in this case the sum ...

In medical imaging, spectroscopy, image processing, cryptography and other areas of science and engineering it is often the case that one wishes to compute multidimensional Fourier transforms of images. This is quite straightforward in Matlab: (multidimensional) images are just n-dimensional matrice...

A minimal Dockerfile looks like this: FROM alpine CMD ["echo", "Hello StackOverflow!"] This will instruct Docker to build an image based on Alpine (FROM), a minimal distribution for containers, and to run a specific command (CMD) when executing the resulting image. Build an...

Group common operations Docker builds images as a collection of layers. Each layer can only add data, even if this data says that a file has been deleted. Every instruction creates a new layer. For example: RUN apt-get -qq update RUN apt-get -qq install some-package Has a couple of downsides: ...

It is possible to save a Docker container's filesystem contents to a tarball archive file. This is useful in a pinch for moving container filesystems to different hosts, for example if a database container has important changes and it isn't otherwise possible to replicate those changes elsewhere. Pl...

Search engines won't index your products if you have a URL like the following: http://www.yourdomain.com/product.php?id=123 SEO friendly URL would look like http://www.yourdomain.com/123/product-name/. The following code helps achieve this without having to change product.php code. RewriteEng...

The method compareTo should be used to compare BigDecimals: BigDecimal a = new BigDecimal(5); a.compareTo(new BigDecimal(0)); // a is greater, returns 1 a.compareTo(new BigDecimal(5)); // a is equal, returns 0 a.compareTo(new BigDecimal(10)); // a is less, returns -1 Commonly you shou...

A powerful alternative to virtualenv is Anaconda - a cross-platform, pip-like package manager bundled with features for quickly making and removing virtual environments. After installing Anaconda, here are some commands to get started: Create an environment conda create --name <envname> pyth...

Query syntax and method syntax are semantically identical, but many people find query syntax simpler and easier to read. Let’s say we need to retrieve all even items ordered in ascending order from a collection of numbers. C#: int[] numbers = { 0, 1, 2, 3, 4, 5, 6 }; // Query syntax: IEnumerab...

We can use 1,2,3.. to determine the type of order: SELECT * FROM DEPT ORDER BY CASE DEPARTMENT WHEN 'MARKETING' THEN 1 WHEN 'SALES' THEN 2 WHEN 'RESEARCH' THEN 3 WHEN 'INNOVATION' THEN 4 ELSE 5 END, CITY IDREGIONCITYDEPARTMENTEMPLOYEES_N...

Sometimes one wants to capture the records that have just been updated. CREATE TABLE #TempUpdated(ID INT) Update TableName SET Col1 = 42 OUTPUT inserted.ID INTO #TempUpdated WHERE Id > 50

WITH cte AS ( SELECT ProjectID, ROW_NUMBER() OVER (PARTITION BY ProjectID ORDER BY InsertDate DESC) AS rn FROM ProjectNotes ) DELETE FROM cte WHERE rn > 1;

The Kernel#require method will load files only once (several calls to require will result in the code in that file being evaluated only once). It will search your ruby $LOAD_PATH to find the required file if the parameter is not an absolute path. Extensions like .rb, .so, .o or .dll are optional. Re...

The method Kernel#autoload registers filename to be loaded (using Kernel::require) the first time that module (which may be a String or a symbol) is accessed. autoload :MyModule, '/usr/local/lib/modules/my_module.rb' The method Kernel#autoload? returns filename to be loaded if name is registere...

When files are not available, the require family will throw a LoadError. This is an example which illustrates loading optional modules only if they exist. module TidBits @@unavailableModules = [] [ { name: 'CoreExtend', file: 'core_extend/lib/core_extend' } \ , { name: 'Fs' ...

The Kernel#load method will evaluate the code in the given file. The search path will be constructed as with require. It will re-evaluate that code on every subsequent call unlike require. There is no load_relative. load `somefile`

You can use any ruby technique to dynamically create a list of files to load. Illustration of globbing for files starting with test, loaded in alphabetical order. Dir[ "#{ __dir__ }**/test*.rb" ) ].sort.each do |source| require_relative source end

DECLARE @DateFrom DATETIME = '2016-06-01 06:00' DECLARE @DateTo DATETIME = '2016-07-01 06:00' DECLARE @IntervalDays INT = 7 -- Transition Sequence = Rest & Relax into Day Shift into Night Shift -- RR (Rest & Relax) = 1 -- DS (Day Shift) = 2 -- NS (Night Shift) = 3 ;WITH roster AS ...

This function returns the floating-point remainder of the division of x/y. The returned value has the same sign as x. #include <math.h> /* for fmod() */ #include <stdio.h> /* for printf() */ int main(void) { double x = 10.0; double y = 5.1; double modulus = fmod(x,...