iterMap3

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

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 );
}