Tutorial by Examples: ev

# example data DT = data.table(iris) To modify factor levels by reference, use setattr: setattr(DT$Species, "levels", c("set", "ver", "vir") # or DT[, setattr(Species, "levels", c("set", "ver", "vir"))] The sec...

When multiple variables are defined at the beginning of the batch, a short definition form may be used by employing a replacement string. @echo off set "vars=_A=good,_B=,_E=bad,_F=,_G=ugly,_C=,_H=,_I=,_J=,_K=,_L=,_D=6 set "%vars:,=" & set "%" for /f %%l in ('set _'...

$ mplayer Lecture_video_part1.mkv $ ^1^2^ mplayer Lecture_video_part2.mkv This command will replace 1 with 2 in the previously executed command. It will only replace the first occurrence of the string and is equivalent to !!:s/1/2/. If you want to replace all occurrences, you have to use !!:gs...

$ apt-get install r-base E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root? $ sudo !! sudo apt-get install r-base [sudo] password for <user>:

private static void GetAllTheAssetsAndFiles(MediaServicesCredentials _medServCredentials) { try { string result = string.Empty; CloudMediaContext mediaContext; mediaContext = new CloudMediaContext(_medServCredentials); ...

A JDK installation and a text editor are the bare minimum for Java development. (It is nice to have a text editor that can do Java syntax highlighting, but you can do without.) However for serious development work it is recommended that you also use the following: A Java IDE such as Eclipse, In...

To mark some expression as an abbreviation, use <abbr> tag: <p>I like to write <abbr title="Hypertext Markup Language">HTML</abbr>!</p> If present, the title attribute is used to present the full description of such abbreviation.

The instance_eval method is available on all objects. It evaluates code in the context of the receiver: object = Object.new object.instance_eval do @variable = :value end object.instance_variable_get :@variable # => :value instance_eval sets self to object for the duration of the c...

Many languages feature a with statement that allows programmers to omit the receiver of method calls. with can be easily emulated in Ruby using instance_eval: def with(object, &block) object.instance_eval &block end The with method can be used to seamlessly execute methods on object...

JSON_MODIFY function can be used to update value on some path. You can use this function to modify original value of JSON cell in UPDATE statement: update Product set Data = JSON_MODIFY(Data, '$.Price', 24.99) where ProductID = 17; JSON_MODIFY function will update or create Price key (if it do...

You can expose values from JSON column as computed columns: CREATE TABLE ProductCollection ( Id int identity primary key, Data nvarchar(max), Price AS JSON_VALUE(Data, '$.Price'), Color JSON_VALUE(Data, '$.Color') PERSISTED ) If you add PERSISTED computed column, value from JSON tex...

This is an Education From in Symfony to take user education details. We wanted to apply validation on 2 fields, education end date and is currently studying. On Post Submit Event, We will check two things 1 - if the user checks the checkbox of is_currently studying then end date should be empty ...

If Sitecore is setup in a CM-CD enviornment there could be a need to fire events on CD server when CM events are fired. The example could be firing publish:end:remote on CD when content editors done publish on CM. In order to make sure that events are firing the following steps are required to be ...

Any String can be evaluated at runtime. class Example def self.foo :foo end end eval "Example.foo" #=> :foo

Ruby keeps track of local variables and self variable via an object called binding. We can get binding of a scope with calling Kernel#binding and evaluate string inside a binding via Binding#eval. b = proc do local_variable = :local binding end.call b.eval "local_variable" #=&gt...

The instance_eval method is available on all objects. It evaluates code in the context of the receiver: object = Object.new object.instance_eval do @variable = :value end object.instance_variable_get :@variable # => :value instance_eval sets self to object for the duration of the co...

The Reflection API could be used to change values of private and final fields even in the JDK default library. This could be used to manipulate the behaviour of some well known classes as we will see. What is not possible Lets start first with the only limitation means the only field we can't chan...

Description: Evaluate expression after user's confirmation. Arguments: ng-confirm-click:(expression) Expression to evaluate when confirmed. ng-confirm-message:(template) Message to be shown in confirm dialog. Code: Directives.directive("ngConfirmClick", ["$parse","...

adb shell am start -n com.android.settings/.DevelopmentSettings Will navigate your device/emulator to the Developer Options section.

Pygame will register all events from the user into an event queue which can be received with the code pygame.event.get(). Every element in this queue is an Event object and they'll all have the attribute type, which is an integer representing what kind of event it is. In the pygame module there are ...