iterator2arrayview

Usage

var iterator2arrayview = require( '@stdlib/iter/to-array-view' );

iterator2arrayview( iterator, dest[, begin[, end]][, mapFcn[, thisArg]] )

Fills an array-like object view with values returned from an iterator.

var Uint8Array = require( '@stdlib/array/uint8' );
var array2iterator = require( '@stdlib/array/to-iterator' );

var iter = array2iterator( [ 1, 2, 3, 4 ] );

var arr = iterator2arrayview( iter, new Uint8Array( 10 ) );
// returns <Uint8Array>[ 1, 2, 3, 4, 0, 0, 0, 0, 0, 0 ]

By default, the function begins filling from the first element of a provided array-like object. To specify an alternative starting index, provide a begin argument (zero-based and inclusive).

var Uint8Array = require( '@stdlib/array/uint8' );
var array2iterator = require( '@stdlib/array/to-iterator' );

var iter = array2iterator( [ 1, 2, 3, 4 ] );

var arr = iterator2arrayview( iter, new Uint8Array( 10 ), 3 );
// returns <Uint8Array>[ 0, 0, 0, 1, 2, 3, 4, 0, 0, 0 ]

If begin is less than 0, the starting index is resolved relative to the last element of the provided array-like object. For example, the following achieves the same behavior as the previous example

var Uint8Array = require( '@stdlib/array/uint8' );
var array2iterator = require( '@stdlib/array/to-iterator' );

var iter = array2iterator( [ 1, 2, 3, 4 ] );

var arr = iterator2arrayview( iter, new Uint8Array( 10 ), -7 );
// returns <Uint8Array>[ 0, 0, 0, 1, 2, 3, 4, 0, 0, 0 ]

By default, the function assumes that a view extends through the last element of a provided array-like object. To specify an alternative last view element, provide an end argument (zero-based and non-inclusive).

var Uint8Array = require( '@stdlib/array/uint8' );
var array2iterator = require( '@stdlib/array/to-iterator' );

var iter = array2iterator( [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ] );

var arr = iterator2arrayview( iter, new Uint8Array( 10 ), 0, 4 );
// returns <Uint8Array>[ 1, 2, 3, 4, 0, 0, 0, 0, 0, 0 ]

If end is less than 0, the last view element is resolved relative to the last element of the provided array-like object. For example, the following achieves the same behavior as the previous example

var Uint8Array = require( '@stdlib/array/uint8' );
var array2iterator = require( '@stdlib/array/to-iterator' );

var iter = array2iterator( [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ] );

var arr = iterator2arrayview( iter, new Uint8Array( 10 ), 0, -6 );
// returns <Uint8Array>[ 1, 2, 3, 4, 0, 0, 0, 0, 0, 0 ]

To invoke a function for each iterated value, provide a callback function.

var Float64Array = require( '@stdlib/array/float64' );
var array2iterator = require( '@stdlib/array/to-iterator' );

function fcn( v ) {
    return v * 10.0;
}

var iter = array2iterator( [ 1, 2, 3, 4 ] );

var arr = iterator2arrayview( iter, new Float64Array( 4 ), fcn );
// returns <Float64Array>[ 10.0, 20.0, 30.0, 40.0 ]

The invoked function is provided three arguments:

• value: iterated value.
• index: destination index.
• n: iteration count (zero-based).

var Uint8Array = require( '@stdlib/array/uint8' );
var array2iterator = require( '@stdlib/array/to-iterator' );

function fcn( v, i ) {
    return v * (i+1);
}

var iter = array2iterator( [ 1, 2, 3, 4 ] );

var arr = iterator2arrayview( iter, new Uint8Array( 4 ), fcn );
// returns <Uint8Array>[ 1, 4, 9, 16 ]

To set the callback function execution context, provide a thisArg.

var Float64Array = require( '@stdlib/array/float64' );
var randu = require( '@stdlib/random/iter/randu' );

function fcn( v ) {
    this.count += 1;
    return v * 10.0;
}

var ctx = {
    'count': 0
};

var arr = iterator2arrayview( randu(), new Float64Array( 10 ), fcn, ctx );
// returns <Float64Array>

var count = ctx.count;
// returns 10