Map (Function)

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Queue, stack, list and array management functions

Constants for managing the arrays

Functions for managing arrays

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Map (Function)

In french: Transforme

Executes a procedure on each element of a source array and returns the results in a WLanguage array.

Example

arrValue is array of int = [1,2,3,4,5]
arrTriple is array of int

// Construct an array with the values multiplied by three
arrTriple = Map(arrValue, AValue => AValue * 3)
// arrTriple contains [3, 6, 9, 12, 15]

// -> apply lowercase to all the strings in the array
// (Prefix syntax)
arr1 is array of strings = ["A", "b", "C"]
arr1 = arr1.Map(X => Lower(X))
// arr1 = ["a", "b", "c"]

Syntax

<Result> = Map(<Source array> , <Operation to perform>)

<Result>: WLanguage array

Array that contains the result of the procedure executed for each element of the <Source array>.

<Source array>: WLanguage array

Name of Array variable to use. This array must be a one-dimensional array.

<Operation to perform>: WLanguage procedure

Name of the WLanguage procedure to be executed for each element of the <Source array>. This procedure can be:
a global or local procedure,
an internal procedure.
It is also possible to directly use a lambda procedure.

Remarks

Operating mode

The <Operation to perform> procedure is called for each element of the source array by passing this element as a parameter.

The results of all calls are stored in the <Result> array.

Remark: You can use the following functions in the same line of code: Filter, Reduce, Apply, Min, Max, Sum, Mean, CheckAnyTrue, CheckAnyFalse, CheckAllTrue, CheckAllFalse.

Related Examples:

Unit examples (WINDEV): Filter / Map / Reduce

[ + ] This example shows how to use the Filter / Map / Reduce functions.
The Filter / Map / Reduce concept allows performing operations on sets of data in a remarkably concise way.
Filter is used to filter an array of elements in a customized way (with a callback procedure).
Map is used to transform an array of elements, also with a callback procedure.
Reduce is used to aggregate data in a customized way with a callback procedure.
Here, this example is used to calculate the average age of women among the users displayed in the table below.

Business / UI classification: Neutral code

Component: wd260vm.dll