iterStep

Create an iterator which returns a sequence of numbers according to a specified increment.

Usage

var iterStep = require( '@stdlib/iter/step' );

iterStep( start, increment[, N] )

Returns an iterator which returns a sequence of numbers according to a specified increment.

var it = iterStep( 0, 2 );
// returns <Object>

var v = it.next().value;
// returns 0

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

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

// ...

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.

By default, the function returns an infinite iterator (i.e., an iterator which never ends). To limit the number of returned values, provide a third argument.

var it = iterStep( 0, 2, 3 );
// returns <Object>

var v = it.next().value;
// returns 0

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

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

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

Notes

The returned iterator is guaranteed to return the start value. Beware, however, that values subsequent to the start value are subject to floating-point rounding errors. For example,

var it = iterStep( 0.1, 0.2 );
// returns <Object>

var v = it.next().value;
// returns 0.1

v = it.next().value;
// returns ~0.3

v = it.next().value;
// returns 0.5

If you desire more control over value precision, consider using roundn:

var roundn = require( '@stdlib/math/base/special/roundn' );
var iterMap = require( '@stdlib/iter/map' );

function round( v ) {
    return roundn( v, -2 );
}

// Create an iterator returning values subject to floating-point errors:
var it1 = iterStep( 0.1, 0.2, 10 );

// Create an iterator to round each value to the nearest hundredth:
var it2 = iterMap( it1, roundn );

// Perform manual iteration...
var v;
while ( true ) {
    v = it2.next();
    if ( v.done ) {
        break;
    }
    console.log( v.value );
}

If an environment supports Symbol.iterator, the returned iterator is iterable.

Examples

var iterStep = require( '@stdlib/iter/step' );

// Create an iterator which is subject to floating-point rounding errors:
var it = iterStep( 0.0, 0.02, 50 );

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