Tutorial by Examples: f

Radix 2 FFT

The simplest and perhaps best-known method for computing the FFT is the Radix-2 Decimation in Time algorithm. The Radix-2 FFT works by decomposing an N point time domain signal into N time domain signals each composed of a single point. Signal decomposition, or ‘decimation in time’ is achieved by b...

algorithm • Fast Fourier Transform

Radix 2 Inverse FFT

Due to the strong duality of the Fourier Transform, adjusting the output of a forward transform can produce the inverse FFT. Data in the frequency domain can be converted to the time domain by the following method: Find the complex conjugate of the frequency domain data by inverting the imaginary...

algorithm • Fast Fourier Transform

Check if file exists

If exist "C:\Foo\Bar.baz" ( Echo File exist ) This checks if the file C:\Foo\Bar.baz's existence. If this exist, it echos File exist The Not operator can also be added.

batch-file • If statements

If variable exists / set

If Defined Foo ( Echo Foo is defined ) This would check if a variable is defined or not. Again, the Not operator can be used.

batch-file • If statements

Depth First Search

Depth First Traversal (or Search) for a graph is similar to Depth First Traversal of a tree. The only catch here is, unlike trees, graphs may contain cycles, so we may come to the same node again. To avoid processing a node more than once, we use a boolean visited array. Below algorithm presents th...

data-structures • Graph traversals

Obtaining the working folder

You can get your working folder by calling the method getFilesDir() on your Activity (Activity is the central class in your application that inherits from Context. See here). Reading is not different. Only your application will have access to this folder. Your activity could contain the following c...

Android • FileIO with Android

Writing raw array of bytes

File myFile = new File(getFilesDir(), "myData.bin"); FileOutputStream out = new FileOutputStream(myFile); // Write four bytes one two three four: out.write(new byte [] { 1, 2, 3, 4} out.close() There is nothing Android specific with this code. If you write lots of small ...

Android • FileIO with Android

Solving "Invisible MTP files" problem.

If you create files for exporting via USB cable to desktop using MTP protocol, may be a problem that newly created files are not immediately visible in the file explorer running on the connected desktop PC. To to make new files visible, you need to call MediaScannerConnection: File file = new File(...

Android • FileIO with Android

Working with big files

Small files are processed in a fraction of second and you can read / write them in place of the code where you need this. However if the file is bigger or otherwise slower to process, you may need to use AsyncTask in Android to work with the file in the background: class FileOperation extends A...

Android • FileIO with Android

Hive UDF to trim the given string.

package MyHiveUDFs; import org.apache.commons.lang.StringUtils; import org.apache.hadoop.hive.ql.exec.UDF; import org.apache.hadoop.io.Text; public class Strip extends UDF { private Text result = new Text(); public Text evaluate(Text str) { if(str == null) { return null; } resul...

hive • Hive User Defined Functions (UDF's)

Inheritance from Parent Class to Child Class

class ParentClass { [string] $Message = "Its under the Parent Class" [string] GetMessage() { return ("Message: {0}" -f $this.Message) } } # Bar extends Foo and inherits its members class ChildClass : ParentClass { } $Inherit = [ChildClass...

PowerShell • PowerShell Classes

Breadth First Search

Algorithm BFS(G) Input graph G Output labeling of the edges and partition of the vertices of G for all u ∈ G.vertices() setLabel(u, UNEXPLORED) for all e ∈ G.edges() setLabel (e, UNEXPLORED) for all v ∈ G.vertices() if getLabel(v) = UNEXPLORED ...

data-structures • Graph traversals

Types of

Make sure you link the Angular and Angular Material libraries! index.html: <html ng-app="mdButtonApp"> <head>  <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.8/angular.min.js"></script&gt...

angular-material • md-button

Loading Dojo specific CSS

The esri.css file does not include the CSS for various Dojo widgets or themes like tundra or claro; those files must be included separately. Exceptions are the Grid and RangeSlider, which are used by widgets in the API. Grid styles must be explicitly included. For instance, this CSS file would be i...

arcgis • ArcGIS JS API

Use generics to enhance type-safety

Let's take this example without using generics protocol JSONDecodable { static func from(_ json: [String: Any]) -> Any? } The protocol declaration seems fine unless you actually use it. let myTestObject = TestObject.from(myJson) as? TestObject Why do you have to cast the result to T...

Swift Language • Generics

Using informats to read data

Informats are used to tell SAS how to read in the data and are identified with an informat statement. data test; infile test.csv; informat id $6. date mmddyy10. cost comma10.2 ; input @1 id @7 date @20 cost ; run; Informats and Format...

sas • SAS Formats

Filters

Variables can be modified using filters. To apply filter to variable follow variable name with pipe | and filter name: {{ variable|filterName }} For example to display variable value in uppercase use construct. {{ variable|upper }} Filters can be parametrized. Filter parameters are passed in...

twig • Basic template syntax

Tutorial by Examples: f

Radix 2 FFT

Radix 2 Inverse FFT

Check if file exists

If variable exists / set

Depth First Search

Obtaining the working folder

Writing raw array of bytes

Solving "Invisible MTP files" problem.

Working with big files

Hive UDF to trim the given string.

Inheritance from Parent Class to Child Class

Breadth First Search

Types of

Loading Dojo specific CSS

Use generics to enhance type-safety

Using informats to read data

Filters

Find a PowerShell module using a pattern

Create the default PowerShell Module Reposity

Find a module by name