@stdlib/array-place NPM

place

Replace elements of an array with provided values according to a provided mask array.

Installation

npm install @stdlib/array-place

Usage

var place = require( '@stdlib/array-place' );

place( x, mask, values[, options] )

Replaces elements of an array with provided values according to a provided mask array.

var x = [ 1, 2, 3, 4 ];

var out = place( x, [ 0, 1, 0, 1 ], [ 20, 40 ] );
// returns [ 1, 20, 3, 40 ]

var bool = ( out === x );
// returns true

The function supports the following parameters:

x: input array.
mask: mask array.
values: values to set.
options: function options.

The function supports the following options:

mode: string specifying behavior when the number of values does not equal the number of truthy mask values. Default: 'repeat'.

The function supports the following modes:

'strict': specifies that the function must raise an exception when the number of values does not exactly equal the number of truthy mask values.
'non_strict': specifies that the function must raise an exception when the function is provided insufficient values to satisfy the mask array.
'strict_broadcast': specifies that the function must broadcast a single-element values array and otherwise raise an exception when the number of values does not exactly equal the number of truthy mask values.
'broadcast': specifies that the function must broadcast a single-element values array and otherwise raise an exception when the function is provided insufficient values to satisfy the mask array.
'repeat': specifies that the function must reuse provided values when replacing elements in x in order to satisfy the mask array.

In broadcasting modes, the function supports broadcasting a values array containing a single element against the number of truthy values in the mask array.

var x = [ 1, 2, 3, 4 ];

var out = place( x, [ 0, 1, 0, 1 ], [ 20 ], {
    'mode': 'strict_broadcast'
});
// returns [ 1, 20, 3, 20 ]

var bool = ( out === x );
// returns true

In repeat mode, the function supports recycling elements in a values array to satisfy the number of truthy values in the mask array.

var x = [ 1, 2, 3, 4 ];

var out = place( x, [ 1, 1, 0, 1 ], [ 20, 40 ], {
    'mode': 'repeat'
});
// returns [ 20, 40, 3, 20 ]

var bool = ( out === x );
// returns true

Notes

The function mutates the input array x.
If a mask array element is truthy, the corresponding element in x is replaced; otherwise, the corresponding element in x is "masked" and thus left unchanged.
The values array must have a data type which can be safely cast to the input array data type. Floating-point data types (both real and complex) are allowed to downcast to a lower precision data type of the same kind (e.g., element values from a 'float64' values array can be assigned to corresponding elements in a 'float32' input array).

Examples

var filledBy = require( '@stdlib/array-base-filled-by' );
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );
var bernoulli = require( '@stdlib/random-base-bernoulli' );
var linspace = require( '@stdlib/array-base-linspace' );
var place = require( '@stdlib/array-place' );

// Generate a linearly spaced array:
var x = linspace( 0, 100, 11 );
console.log( x );

// Generate a random mask array:
var N = discreteUniform( 5, 15 );
var mask = filledBy( N, bernoulli.factory( 0.3 ) );
console.log( mask );

// Generate an array of random values:
var values = filledBy( N, discreteUniform.factory( 1000, 2000 ) );
console.log( values );

// Update a random sample of elements in `x`:
var out = place( x, mask, values );
console.log( out );

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.

@stdlib/array-place v0.1.1