iterStep

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

Installation

npm install @stdlib/iter-step

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 );
}

See Also

• @stdlib/array-from-iterator: create (or fill) an array from an iterator.
• @stdlib/iter-datespace: create an iterator which returns evenly spaced dates over a specified interval.
• @stdlib/iter-incrspace: create an iterator which returns evenly spaced numbers according to a specified increment.
• @stdlib/iter-linspace: create an iterator which returns evenly spaced numbers over a specified interval.
• @stdlib/iter-logspace: create an iterator which returns evenly spaced numbers on a log scale.
• @stdlib/iter-unitspace: create an iterator which returns numbers incremented by one.

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.