<Array>.Reduce (Function)

ONLINE HELP
WINDEV, WEBDEV AND WINDEV MOBILE

Version:

Home | Sign in | English

Queue, stack, list and array management functions

Existing computations

Constants for managing the arrays

Functions for managing arrays

Operating mode
Existing computations

WINDEV

WEBDEV

WINDEV Mobile

Others

See also

Reduce (Function)

<Array>.Reduce (Function)

In french: <Tableau>.Agrège

Applies a computation to each element of a WLanguage array.

Example

arrValue is array of int = [1,2,3,4,5]
TheSum is integer
TheSum = arrValue.Reduce((Value, TheSum) => { RESULT Value + TheSum }, 0)

// Note: this example is for illustrative purposes ; to find the sum of elements of an array,
// it is preferable to use the Sum function

Syntax

<Result> = <Array>.Reduce(<Operation to perform> [, <InitialValue>])

<Result>: Type corresponding to the result

Result of the requested reduce operation.

<Array>: WLanguage array

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

<Operation to perform>: WLanguage procedure

Name of WLanguage procedure to run. This procedure can be:
a global or local procedure,
an internal procedure.
It is also possible to directly use a lambda.

<InitialValue>: Optional parameter, type corresponding to the initial value

Initial value to use the first time the <Operation to perform> procedure is run.

Remarks

Operating mode

The <Operation to perform> procedure is called a first time with two parameters:

the first element of the array,
the initial value specified with <Initial value>.

The procedure is then called for all other elements of the array with two parameters:

the element of the array,
the value returned by the previous call.

Illustrative example
Let's study the following example:

arrValue is array of int = [1,2,3,4,5]
TheSum is integer
TheSum = Reduce(arrValue, (Value, TheSum) => { RESULT Value + TheSum }, 0)

In this example, the code:

TheSum = arrValue.Reduce((Value, TheSum) => { RESULT Value + TheSum }, 0)

is equivalent to the following code:

TheSum = arrValue.Reduce(Add, 0)

INTERNAL PROCEDURE Add(Value, Total)
RESULT Value + Total
END

With this internal procedure, the calculation can be broken down as follows:

IntermediateResult1 = Add (t[1], InitialValue): in the example Add( 1, 0 ) -> 1
IntermediateResult2 = Add (t[2], IntermediateResult1): in the example Add( 2, 1 ) -> 3
...

Remark: this example is for illustrative purposes; to find the sum of elements of an array, it is preferable to use Sum.

Existing computations

The most common computations are available in WLanguage:


Versions 17 and later Mean New in version 17 Mean Mean	Calculates the mean of several elements: elements found in an array, numeric values, ...
Versions 17 and later Sum New in version 17 Sum Sum	Calculates the sum of the array elements.

Business / UI classification : Neutral code

Component : wd260vm.dll