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README.md

iterator2array

Create (or fill) an array from an iterator.

Usage

var iterator2array = require( '@stdlib/array/from-iterator' );

iterator2array( iterator[, out][, mapFcn[, thisArg]] )

Creates (or fills) an array from an iterator.

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

var opts = {
    'iter': 10
};

var arr = iterator2array( randu( opts ) );
// returns <Array>

By default, the function creates and fills a generic array. To fill an array-like object, provide an out argument.

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

var out = new Float64Array( 10 );

var arr = iterator2array( randu(), out );
// returns <Float64Array>

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

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

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

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

var arr = iterator2array( array2iterator( [ 1, 2, 3, 4 ] ), fcn );
// returns [ 10.0, 20.0, 30.0, 40.0 ]

The invoked function is provided two arguments:

  • value: iterated value.
  • index: iterated value index.
var Float64Array = require( '@stdlib/array/float64' );
var randu = require( '@stdlib/random/iter/randu' );

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

var arr = iterator2array( randu(), new Float64Array( 10 ), fcn );
// returns <Float64Array>

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 = iterator2array( randu(), new Float64Array( 10 ), fcn, ctx );
// returns <Float64Array>

var count = ctx.count;
// returns 10

Notes

  • If provided an output array, the function fills the output array with iterated values.
  • Iteration stops when an output array is full or an iterator finishes; whichever comes first.
  • By providing an output typed array, one avoids the temporary memory allocation when using the built-in TypedArray.from.

Examples

var Float64Array = require( '@stdlib/array/float64' );
var randu = require( '@stdlib/random/iter/randu' );
var iterator2array = require( '@stdlib/array/from-iterator' );

var opts;
var arr;
var it;
var i;

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

// Create an iterator for generating uniformly distributed pseudorandom numbers:
opts = {
    'iter': 10
};
it = randu( opts );

// Fill an array with scaled iterator values:
arr = iterator2array( it, new Float64Array( opts.iter ), scale );

for ( i = 0; i < arr.length; i++ ) {
    console.log( arr[ i ] );
}

See Also