countBy
countBy<T>(array: Array<T>, matchingFunction: (T) -> Boolean): Number
Counts the elements in an array that return true when the matching function is applied to the value of each element.
Parameters
| Name | Description |
|---|---|
|
The input array that contains elements to match. |
|
A function to apply to elements in the input array. |
Example
This example counts the number of elements in the input array ([1, 2, 3, 4]) that
return true when the function (($ mod 2) == 0) is applied their values. In this
case, the values of two of the elements, both 2 and 4, match because
2 mod 2 == 0 and 4 mod 2 == 0. As a consequence, the countBy function returns 2.
Note that mod returns the modulus of the operands.
Source
%dw 2.0
import * from dw::core::Arrays
output application/json
---
{ "countBy" : [1, 2, 3, 4] countBy (($ mod 2) == 0) }DataWeaveOutput
{ "countBy": 2 }JSONcountBy(array: Null, matchingFunction: (Nothing) -> Any): Null
Helper function that enables countBy to work with a null value.
Introduced in DataWeave version 2.4.0.