map2

Usage

var map2 = require( '@stdlib/utils/map2' );

map2( x, y, fcn[, thisArg] )

Applies a function to elements in two input arrays and assigns the results to a new array.

var naryFunction = require( '@stdlib/utils/nary-function' );
var add = require( '@stdlib/math/base/ops/add' );

var x = [ 1, 2, 3, 4, 5, 6 ];
var y = [ 1, 1, 1, 1, 1, 1 ];

var out = map2( x, y, naryFunction( add, 2 ) );
// returns [ 2, 3, 4, 5, 6, 7 ]

The function accepts both array-like objects and ndarray-like objects.

var naryFunction = require( '@stdlib/utils/nary-function' );
var add = require( '@stdlib/math/base/ops/add' );
var array = require( '@stdlib/ndarray/array' );

var opts = {
    'dtype': 'generic'
};
var x = array( [ [ 1, 2, 3 ], [ 4, 5, 6 ] ], opts );
var y = array( [ [ 1, 1, 1 ], [ 1, 1, 1 ] ], opts );

var out = map2( x, y, naryFunction( add, 2 ) );
// returns <ndarray>

var v = out.get( 1, 1 );
// returns 6

The applied function is provided the following arguments:

• v1: element from first input array.
• v2: element from second input array.
• idx: element index.
• x: first input array.
• y: second input array.

To set the this context when invoking the input function, provide a thisArg.

var add = require( '@stdlib/math/base/ops/add' );

function fcn( v1, v2 ) {
    this.count += 1;
    return add( v1, v2 );
}

var x = [ 1, 2, 3, 4, 5, 6 ];
var y = [ 1, 1, 1, 1, 1, 1 ];

var ctx = {
    'count': 0
};

var out = map2( x, y, fcn, ctx );
// returns [ 2, 3, 4, 5, 6, 7 ]

var cnt = ctx.count;
// returns 6

map2.assign( x, y, out, fcn[, thisArg] )

Applies a function to elements in two input arrays and assigns the results to an output array out.

var naryFunction = require( '@stdlib/utils/nary-function' );
var add = require( '@stdlib/math/base/ops/add' );

var x = [ 1, 2, 3, 4, 5, 6 ];
var y = [ 1, 1, 1, 1, 1, 1 ];
var out = [ 0, 0, 0, 0, 0, 0 ];

map2.assign( x, y, out, naryFunction( add, 2 ) );

console.log( out );
// => [ 2, 3, 4, 5, 6, 7 ]

The method accepts both array-like objects and ndarray-like objects.

var naryFunction = require( '@stdlib/utils/nary-function' );
var add = require( '@stdlib/math/base/ops/add' );
var array = require( '@stdlib/ndarray/array' );

var opts = {
    'dtype': 'generic',
    'shape': [ 2, 3 ]
};
var x = array( [ [ 1, 2, 3 ], [ 4, 5, 6 ] ], opts );
var y = array( [ [ 1, 1, 1 ], [ 1, 1, 1 ] ], opts );
var out = array( opts );

map2.assign( x, y, out, naryFunction( add, 2 ) );

var v = out.get( 1, 1 );
// returns 6

Input and output arrays must be either all array-like objects or all ndarray-like objects. If input and output arrays are array-like objects, all arrays must have the same number of elements.

If input and output arrays are ndarray-like objects, the arrays must be broadcast compatible. To map from one or more input ndarrays to an output ndarray which has the same rank (i.e., dimensionality) and the same number of elements, but which is not broadcast compatible, reshape the arrays prior to invocation.

var naryFunction = require( '@stdlib/utils/nary-function' );
var add = require( '@stdlib/math/base/ops/add' );
var array = require( '@stdlib/ndarray/array' );

var opts = {
    'dtype': 'generic',
    'shape': [ 2, 3 ]
};
var x = array( [ [ 1, 2, 3 ], [ 4, 5, 6 ] ], opts );
var y = array( [ [ 1, 1, 1 ], [ 1, 1, 1 ] ], opts );

opts = {
    'dtype': 'generic',
    'shape': [ 2, 2, 3 ]  // broadcast compatible shape
};
var out = array( opts );

map2.assign( x, y, out, naryFunction( add, 2 ) );

var v = out.get( 0, 1, 1 );
// returns 6

v = out.get( 1, 1, 1 );
// returns 6

In general, avoid providing output ndarray-like objects which are non-contiguous views containing one or more elements referring to the same memory location. Writing to an overlapping non-contiguous view is likely to simultaneously affect multiple elements and yield unexpected results.

The applied function is provided the same arguments as with map2.