External module "utils/map-reduce-right/docs/types/index.d"

Export assignment mapReduceRight

• mapReduceRight<T, U, V, W>(arr: typedndarray<T>, initial: V, mapper: Mapper<T, U>, reducer: Reducer<U, V, T, W>, thisArg?: ThisParameterType<Reducer<U, V, T, W>>): V
• mapReduceRight<T, U, V, W>(arr: Collection<T>, initial: V, mapper: ArrayMapper<T, U>, reducer: ArrayReducer<U, V, T, W>, thisArg?: ThisParameterType<ArrayReducer<U, V, T, W>>): V

• Performs a map-reduce operation for each element in an array while iterating from right to left and returns the accumulated result.

  Notes

  • The mapping function is provided four arguments:

    • value: array element.
    • index: element index.
    • arr: input array.

  • The reducing function is provided four arguments:

    • accumulator: accumulated value.
    • value: result after applying a mapping function to the current array element.
    • index: element index.
    • arr: input array.

  • If provided an empty array, the function returns the initial value.

  Type parameters

  • T

  • U

  • V

  • W

  Parameters

  • arr: typedndarray<T>

    input array

  • initial: V

    initial value

  • mapper: Mapper<T, U>

    mapping function

  • reducer: Reducer<U, V, T, W>

    reducing function

  • Optional thisArg: ThisParameterType<Reducer<U, V, T, W>>

    reducing function execution context

  Returns V

  accumulated result

  Example

  var naryFunction = require( '@stdlib/utils/nary-function' );
  var abs = require( '@stdlib/math/base/special/abs' );
  var add = require( '@stdlib/math/base/ops/add' );
  var array = require( '@stdlib/ndarray/array' );
  
  var opts = {
      'dtype': 'generic'
  };
  var arr = array( [ [ -1, -2, -3 ], [ -4, -5, -6 ] ], opts );
  
  var out = mapReduceRight( arr, 0, naryFunction( abs, 2 ), naryFunction( add, 2 ) );
  // returns 21

• Performs a map-reduce operation for each element in an array while iterating from right to left and returns the accumulated result.

  Notes

  • The mapping function is provided four arguments:

    • value: array element.
    • index: element index.
    • arr: input array.

  • The reducing function is provided four arguments:

    • accumulator: accumulated value.
    • value: result after applying a mapping function to the current array element.
    • index: element index.
    • arr: input array.

  • If provided an empty array, the function returns the initial value.

  Type parameters

  • T

  • U

  • V

  • W

  Parameters

  • arr: Collection<T>

    input array

  • initial: V

    initial value

  • mapper: ArrayMapper<T, U>

    mapping function

  • reducer: ArrayReducer<U, V, T, W>

    reducing function

  • Optional thisArg: ThisParameterType<ArrayReducer<U, V, T, W>>

    reducing function execution context

  Returns V

  accumulated result

  Example

  function square( value ) {
      return value * value;
  }
  
  function sum( acc, value ) {
      return acc + value;
  }
  
  var arr = [ 1, 2, 3, 4 ];
  
  var out = mapReduceRight( arr, 0, square, sum );
  // returns 30