iterReject

Create an iterator which rejects the values of another iterator according to a predicate function.

Usage

var iterReject = require( '@stdlib/iter/reject' );

iterReject( iterator, predicate[, thisArg] )

Returns an iterator which rejects the values of another iterator according to a predicate function.

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

function predicate( v ) {
    return ( v > 2 );
}

var it = iterReject( array2iterator( [ 1, 3, 2, 4 ] ), predicate );
// returns <Object>

var v = it.next().value;
// returns 1

v = it.next().value;
// returns 2

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

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 predicate function is provided two arguments:

  • value: iterated value
  • index: iteration index (zero-based)
var array2iterator = require( '@stdlib/array/to-iterator' );

function predicate( v, i ) {
    return ( i >= 2 );
}

var it = iterReject( array2iterator( [ 3, 4, 1, 2 ] ), predicate );
// returns <Object>

var v = it.next().value;
// returns 3

v = it.next().value;
// returns 4

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

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

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

function predicate( v ) {
    this.count += 1;
    return ( v > 10 );
}

var ctx = {
    'count': 0
};

var it = iterReject( array2iterator( [ 1, 2, 3, 4 ] ), predicate, ctx );
// returns <Object>

var v = it.next().value;
// returns 1

v = it.next().value;
// returns 2

v = it.next().value;
// returns 3

var count = ctx.count;
// returns 3

Notes

  • If an environment supports Symbol.iterator and a provided iterator is iterable, the returned iterator is iterable.

Examples

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

function predicate( v ) {
    return ( v > 0.5 );
}

// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
    'seed': 1234,
    'iter': 20
});

// Create an iterator which filters the generated numbers:
var it = iterReject( rand, predicate );

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