collection.map( )

Home

4D v19.8

collection.map( )


collection.map ( methodName {; param}{; param2 ; ... ; paramN} ) -> Function result

Parameter	Type	Description
methodName	Text	Name of method used to transform the collection elements
param	Expression	Parameter(s) for the method
Function result	Collection	Collection of transformed values

Description

The collection.map( ) method creates a new collection based upon the result of the call of the methodName method on each element of the original collection. Optionally, you can pass parameters to methodName using the param parameter(s). collection.map( ) always returns a collection with the same size as the original collection.

Note: This method does not modify the original collection.

methodName receives the following parameters:

in $1.value (any type): element value to be mapped
in $2 (any type): param
in $N... (any type): param2...paramN

methodName sets the following parameter(s):

$1.result (any type): new transformed value to add to the resulting collection
$1.stop (boolean): true to stop the method callback. The returned value is the last calculated.

Example

 C_COLLECTION($c;$c2)

 $c:=New collection(1;4;9;10;20)

 $c2:=$c.map("Percentage";$c.sum())

  //$c2=[2.27,9.09,20.45,22.73,45.45]

Here is the Percentage method:

 C_OBJECT($1)

 C_REAL($2)

 $1.result:=Round(($1.value/$2)*100;2)