iterMap3

Create an iterator which invokes a ternary function accepting numeric arguments for each iterated value.

Installation

npm install @stdlib/math-iter-tools-map3

Usage

var iterMap3 = require( '@stdlib/math-iter-tools-map3' );

iterMap3( iter0, iter1, iter2, fcn[, options] )

Returns an iterator which invokes a ternary function accepting numeric arguments for each iterated value.

var array2iterator = require( '@stdlib/array-to-iterator' );
var clamp = require( '@stdlib/math-base-special-clamp' );

var x = array2iterator( [ 1.0, -2.0, 3.0, 14.0 ] );
var min = array2iterator( [ 1.0, 0.0, -1.0, 1.0 ] );
var max = array2iterator( [ 10.0, 10.0, 2.0, 10.0 ] );

var it = iterMap3( x, min, max, clamp );
// returns <Object>

var r = it.next().value;
// returns 1.0

r = it.next().value;
// returns 0.0

r = it.next().value;
// returns 2.0

// ...

The returned iterator protocol-compliant object has the following properties:

• next: function which returns an iterator protocol-compliant object containing the next iterated value (if one exists) assigned to a value property and a done property having a boolean value indicating whether the iterator is finished.
• return: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object.

The invoked function is provided three arguments:

• x: iterated value from first input iterator.
• y: iterated value from second input iterator.
• z: iterated value from third input iterator.

var array2iterator = require( '@stdlib/array-to-iterator' );

function fcn( x, y, z ) {
    return x + y + z + 10;
}

var it1 = array2iterator( [ 1, 2, 3, 4 ] );
var it2 = array2iterator( [ 1, 2, 3, 4 ] );
var it3 = array2iterator( [ 1, 2, 3, 4 ] );

var it = iterMap3( it1, it2, it3, fcn );
// returns <Object>

var r = it.next().value;
// returns 13

r = it.next().value;
// returns 16

r = it.next().value;
// returns 19

// ...

The function supports the following options:

• invalid: return value when an input iterator yields a non-numeric value. Default: NaN.

By default, the function returns an iterator which returns NaN when an input iterator yields a non-numeric value. To specify a different return value, set the invalid option.

var array2iterator = require( '@stdlib/array-to-iterator' );
var clamp = require( '@stdlib/math-base-special-clamp' );

var it1 = array2iterator( [ '1.0', '2.0', '3.0' ] );
var it2 = array2iterator( [ 0.0, 0.0, 0.0 ] );
var it3 = array2iterator( [ 10.0, 10.0, 10.0 ] );

var opts = {
    'invalid': null
};
var it = iterMap3( it1, it2, it3, clamp, opts );
// returns <Object>

var v = it.next().value;
// returns null

v = it.next().value;
// returns null

// ...

If provided a numeric value as an iterator argument, the value is broadcast as an infinite iterator which always returns the provided value.

var array2iterator = require( '@stdlib/array-to-iterator' );
var clamp = require( '@stdlib/math-base-special-clamp' );

var x = array2iterator( [ -1.0, 20.0 ] );

var it = iterMap3( x, 0.0, 10.0, clamp );
// returns <Object>

var v = it.next().value;
// returns 0.0

v = it.next().value;
// returns 10.0

var bool = it.next().done;
// returns true

Notes

• If an iterated value is non-numeric (including NaN), the returned iterator returns NaN. If non-numeric iterated values are possible, you are advised to provide an iterator which type checks and handles non-numeric values accordingly.
• The length of the returned iterator is equal to the length of the shortest provided iterator. In other words, the returned iterator ends once one of the provided iterators ends.
• If an environment supports Symbol.iterator and a provided iterator is iterable, the returned iterator is iterable.

Examples

var uniform = require( '@stdlib/random-iter-uniform' );
var clamp = require( '@stdlib/math-base-special-clamp' );
var iterMap3 = require( '@stdlib/math-iter-tools-map3' );

// Create seeded iterators for generating pseudorandom numbers:
var x = uniform( 0.0, 10.0, {
    'seed': 1234,
    'iter': 10
});

var min = uniform( 0.0, 1.0, {
    'seed': 4567,
    'iter': 10
});

var max = uniform( 9.0, 10.0, {
    'seed': 7895,
    'iter': 10
});

// Create an iterator which consumes the pseudorandom number iterators:
var it = iterMap3( x, min, max, clamp );

// Perform manual iteration...
var r;
while ( true ) {
    r = it.next();
    if ( r.done ) {
        break;
    }
    console.log( r.value );
}

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.