unary2dBy

Apply a unary function to each element retrieved from a two-dimensional nested input array according to a callback function and assign results to elements in a two-dimensional nested output array.

Installation

npm install @stdlib/array-base-unary2d-by

Usage

var unary2dBy = require( '@stdlib/array-base-unary2d-by' );

unary2dBy( arrays, shape, fcn, clbk[, thisArg] )

Applies a unary function to each element retrieved from a two-dimensional nested input array according to a callback function and assigns results to elements in a two-dimensional nested output array.

var abs = require( '@stdlib/math-base-special-abs' );

function accessor( v ) {
    return v * 2.0;
}

var x = [ [ -1.0, -2.0 ], [ -3.0, -4.0 ] ];
var shape = [ 2, 2 ];

unary2dBy( [ x, x ], shape, abs, accessor );
// x => [ [ 2.0, 4.0 ], [ 6.0, 8.0 ] ]

The function accepts the following arguments:

• arrays: array-like object containing one input nested array and one output nested array.
• shape: array shape.
• fcn: unary function to apply to callback return values.
• clbk: callback function.
• thisArg: callback function execution context (optional).

The invoked callback function is provided the following arguments:

• value: array element.
• indices: current array element indices.
• arrays: input and output arrays.

To set the callback execution context, provide a thisArg.

var abs = require( '@stdlib/math-base-special-abs' );

function accessor( v ) {
    this.count += 1;
    return v * 2.0;
}

var context = {
    'count': 0
};

var x = [ [ -1.0, -2.0 ], [ -3.0, -4.0 ] ];
var y = [ [ 0.0, 0.0 ], [ 0.0, 0.0 ] ];

var shape = [ 2, 2 ];

unary2dBy( [ x, y ], shape, abs, accessor, context );
// y => [ [ 2.0, 4.0 ], [ 6.0, 8.0 ] ]

var cnt = context.count;
// returns 4

Notes

• If a provided callback function does not return any value (or equivalently, explicitly returns undefined), the value is ignored.

  var abs = require( '@stdlib/math-base-special-abs' );
  
  function accessor() {
      // No-op...
  }
  
  var x = [ [ -1.0, -2.0 ], [ -3.0, -4.0 ] ];
  var y = [ [ 0.0, 0.0 ], [ 0.0, 0.0 ] ];
  
  var shape = [ 2, 2 ];
  
  unary2dBy( [ x, y ], shape, abs, accessor );
  // y => [ [ 0.0, 0.0 ], [ 0.0, 0.0 ] ]

• The function assumes that the input and output arrays have the same shape.

Examples

var discreteUniform = require( '@stdlib/random-base-discrete-uniform' ).factory;
var bernoulli = require( '@stdlib/random-base-bernoulli' );
var filled2dBy = require( '@stdlib/array-base-filled2d-by' );
var zeros2d = require( '@stdlib/array-base-zeros2d' );
var abs = require( '@stdlib/math-base-special-abs' );
var unary2dBy = require( '@stdlib/array-base-unary2d-by' );

function accessor( v ) {
    // Randomly determine whether a value should be considered "missing":
    return ( bernoulli( 0.5 ) > 0 ) ? v : void 0;
}

var shape = [ 3, 3 ];

var x = filled2dBy( shape, discreteUniform( -100, 100 ) );
console.log( x );

var y = zeros2d( shape );
console.log( y );

unary2dBy( [ x, y ], shape, abs, accessor );
console.log( y );

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.