This module contains helper functions for working with arrays.

To use this module, you must import it to your DataWeave code, for example, by adding the line import * from dw::core::Arrays to the header of your DataWeave script.

Functions

countBy

countBy(Array<T>, (T) → Boolean): Number

Counts the elements in a list (array) that match the results of a function.

Parameters

Name Description

array

The input list that contains elements to match.

matchingFunction

A function to apply to the input list.

Example

This counts the values in the list that are equal to the result of the matchingFunction ((($ mod 2) == 0)).

Source


  
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 %dw 2.0
 import * from dw::core::Arrays
 output application/json
 ---
{ "countBy" : [1, 2, 3, 4] countBy (($ mod 2) == 0) }

Output


  
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{ "countBy": 2 }

divideBy

divideBy(Array<T>, Number): Array<Array<T>>

Breaks up a list (array) into sub-lists (sub-arrays) that contain the specified number of elements.

If there are fewer elements in the input array than the specified number, the function will fill the sub-array with those elements. If there are more elements, the function will fill as many sub-arrays needed with the extra elements.

Parameters

Name Description

items

Items in the input array.

amount

The number of elements allowed per sub-array.

Example

This example breaks up arrays into sub-arrays based on the specified amount.

Source


  
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%dw 2.0
import * from dw::core::Arrays
output application/json
---
{
  "divideBy" : [
      { "divideBy2" : [1, 2, 3, 4, 5] divideBy 2 },
      { "divideBy2" : [1, 2, 3, 4, 5, 6] divideBy 2 },
      { "divideBy3" : [1, 2, 3, 4, 5] divideBy 3 }
  ]
}

Output


  
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{
 "divideBy": [
  {
    "divideBy2": [
      [ 1, 2 ],
      [ 3, 4 ],
      [ 5 ]
    ]
  },
  {
    "divideBy2": [
      [ 1, 2 ],
      [ 3, 4 ],
      [ 5, 6 ]
    ]
  },
    {
      "divideBy3": [
        [ 1, 2, 3 ],
        [ 4, 5 ]
      ]
    }
 ]
}

every

every(Array<T>, (T) → Boolean): Boolean

Returns true if every element in the list (array) matches the condition.

The function stops iterating after the first negative evaluation of a list.

Parameters

Name Description

list

The input list.

condition

A condition (or expression) to apply to the input list.

Example

This example applies a variety of expressions to the input lists.

Source


  
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%dw 2.0
import * from dw::core::Arrays
var arr0 = [] as Array<Number>
output application/json
---
{ "results" : [
     "ok" : [
        [1,1,1] every ($ == 1),
        [1] every ($ == 1)
     ],
     "err" : [
        [1,2,3] every ((log('should stop at 2 ==', $) mod 2) == 1),
        [1,1,0] every ($ == 1),
        [0,1,1,0] every (log('should stop at 0 ==', $) == 1),
        [1,2,3] every ($ == 1),
        arr0 every true,
     ]
   ]
 }

Output


  
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{
   "results": [
     {
       "ok": [ true, true ]
     },
     {
       "err": [ false, false, false, false, false ]
     }
   ]
 }

some

some(Array<T>, (T) → Boolean): Boolean

Returns true if an element in the list (an array) matches the specified condition.

The function stops iterating after the first match to an element in the list.

Parameters

Name Description

list

The input list.

condition

A condition (or expression) to apply to the input list.

Example

This example applies a variety of expressions to the input lists.

Source


  
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 %dw 2.0
 import * from dw::core::Arrays
 output application/json
 ---
 { "results" : [
     "ok" : [
       [1,2,3] some (($ mod 2) == 0),
       [1,2,3] some (($ mod 2) == 1),
       [1,2,3,4,5,6,7,8] some (log('should stop at 2 ==', $) == 2),
       [1,2,3] some ($ == 1),
       [1,1,1] some ($ == 1),
       [1] some ($ == 1)
     ],
     "err" : [
       [1,2,3] some ($ == 100),
       [1] some ($ == 2)
     ]
   ]
}

Output


  
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{
   "results": [
     {
       "ok": [ true, true, true, true, true, true ]
     },
     {
       "err": [ false, false ]
     }
   ]
 }

sumBy

sumBy(Array<T>, (T) → Number): Number

Returns the sum of the values of the elements in a list (an array).

Parameters

Name Description

array

The input list.

numberSelector

A DataWeave selector that selects the values of the numbers in the input list.

Example

This example calculates the sum of the values of elements some lists. Notice that both of the sumBy function calls produce the same result.

Source


  
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 %dw 2.0
 import * from dw::core::Arrays
 output application/json
 ---
{
  "sumBy" : [
    [ { a: 1 }, { a: 2 }, { a: 3 } ] sumBy $.a,
    sumBy([ { a: 1 }, { a: 2 }, { a: 3 } ], (item) -> item.a)
  ]
}

Output


  
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{ "sumBy" : [ 6, 6 ] }