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When it comes to geographic data, R shows to be a powerful tool for data handling, analysis and visualisation. Often, spatial data is avaliable as an XY coordinate data set in tabular form. This example will show how to create a spatial data set from an XY data set. The packages rgdal and sp provi...

rgdal ESRI shape files can easily be imported into R by using the function readOGR() from the rgdal package. library(rgdal) shp <- readORG(dsn = "/path/to/your/file", layer = "filename") It is important to know, that the dsn must not end with / and the layer does not all...

package { import flash.text.TextField; import flash.display.Sprite; public class TextHello extends Sprite { public function TextHello() { var tf:TextField = new TextField(); tf.text = "Hello World!" tf.x = 50; tf...

Concurrent collections are a generalization of thread-safe collections, that allow for a broader usage in a concurrent environment. While thread-safe collections have safe element addition or removal from multiple threads, they do not necessarily have safe iteration in the same context (one may not...

'Prefer composition over inheritance' is an important and popular programming principle, used to assign behaviors to objects, as opposed to inheriting many often unneeded behaviors. Behaviour factories var speaker = function (state) { var noise = state.noise || 'grunt'; return { ...

macro(set_my_variable _INPUT) if("${_INPUT}" STREQUAL "Foo") set(my_output_variable "foo") else() set(my_output_variable "bar") endif() endmacro(set_my_variable) Use the macro: set_my_variable("Foo") message(STATUS ${my_outpu...

macro(set_custom_variable _OUT_VAR) set(${_OUT_VAR} "Foo") endmacro(set_custom_variable) Use it with set_custom_variable(my_foo) message(STATUS ${my_foo}) which will print -- Foo

The difference between size and count is: size counts NaN values, count does not. df = pd.DataFrame( {"Name":["Alice", "Bob", "Mallory", "Mallory", "Bob" , "Mallory"], "City":["Seattle", &q...

var a:Object; trace(a); // null trace(a.b); // Error 1009 Here, an object reference is declared, but is never assigned a value, be it with new or assignment of a non-null value. Requesting its properties or method results in a 1009 error.

x=anObject.aProperty.anotherProperty.getSomething().data; Here, any object before the dot can end up being null, and using methods that return complex objects only increases the complication to debug the null error. Worst case if the method is prone to extraneous failures, say retrieving data ove...

s=this.getChildByName("garbage"); if (s.parent==this) {...} getChildByName() is one of the many functions that can return null if an error occurred when processing its input. Therefore, if you are receiving an object from any function that can possibly return null, check for null first...

addEventListener(Event.ENTER_FRAME,moveChild); function moveChild(e:Event):void { childMC.x++; if (childMC.x>1000) { gotoAndStop(2); } } This example will move the childMC (added to Main at design time) but will instantly throw a 1009 as soon as gotoAndStop() is invok...

prerequisite of scrapy installation: Python 2.7 or above 3.3 pip and setuptools Python packages. lxml OpenSSL. You can install Scrapy using pip. To install using pip run: pip install Scrapy Platform specific installation Anaconda This is the recommended way to install Scrapy. ...

To destroy, delete, or unset an array: unset array To destroy, delete, or unset a single array element: unset array[10]

4.0 Declare an associative array declare -A aa Declaring an associative array before initialization or use is mandatory. Initialize elements You can initialize elements one at a time as follows: aa[hello]=world aa[ab]=cd aa["key with space"]="hello world" You can al...

Get the list of inialized indexes in an array $ arr[2]='second' $ arr[10]='tenth' $ arr[25]='twenty five' $ echo ${!arr[@]} 2 10 25

Windows There are two options how to install Kivy: First ensure python tools are up-to-date. python -m pip install --upgrade pip wheel setuptools Then install the basic dependencies. python -m pip install docutils pygments pypiwin32 kivy.deps.sdl2 kivy.deps.glew Although Kivy already has p...

Rescue from record not found error instead of showing an exception or white page: class ApplicationController < ActionController::Base # ... your other stuff here rescue_from ActiveRecord::RecordNotFound do |exception| redirect_to root_path, 404, alert: 'Record not found' en...

The JsonPipe can be used for debugging the state of any given internal. Code @Component({ selector: 'json-example', template: `<div> <p>Without JSON pipe:</p> <pre>{{object}}</pre> <p>With JSON pipe:</p> <pre>{{object | json...

You can install three.js via npm: npm install three You can add it from a CDN to your HTML: <script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r83/three.js"></script> You can use the three.js editor to give it a try and download the project as an ex...