Definition

object to_dictionary(array[any] $array, expression->string $keyExpression, expression->any $valueExpression)

Converts $array into an object. Evaluates $keyExpression against the $array elements, and each unique result of a $keyExpression yields a key. The value is an array whose elements are the evaluations of $valueExpression on the elements that yield the same result upon evaluating the $keyExpression.

Parameters

array[any] $array

Array to convert to object.

expression->string $keyExpression

Expression defining the keys of the new dictionary.

expression->any $valueExpression

Expression defining the values in the array assigned to keys resulting from $keyExpression

Returns

object

Object where the keys are the results of evaluating $keyExpression against $array elements, and values equal to arrays of results of applying $valueExpression to the elements with equal $keyExpression values. For elements where $keyExpression evaluates to null, the default key name is _.

Examples

{
  "simpleArray": [1, 2, 3],
  "objectArray": [
    {
      "Region": "Germany",
      "Product": "Apple",
      "Units": "51"
    },
    {
      "Region": "Denmark",
      "Product": "Apple",
      "Units": "99"
    },
    {
      "Region": "Germany",
      "Product": "Orange",
      "Units": "66"
    },
    {
      "Product": "Apple",
      "Units": "51"
    }
  ]
}

{
  a: to_dictionary(simpleArray, join('', ['key', to_string(@)]), @),
  b: to_dictionary(objectArray, &Region, &@.Product)
}

{
  "a": {
    "key1": [1],
    "key2": [2],
    "key3": [3]
  },
  "b": {
    "Germany": ["Apple", "Orange"],
    "Denmark": ["Apple"],
    "_": ["Apple"]
  }
}