Create an iterator which removes consecutive duplicated values.
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> Create an [iterator][mdn-iterator-protocol] which removes consecutive duplicated values.
``bash`
npm install @stdlib/iter-dedupe
`javascript`
var iterDedupe = require( '@stdlib/iter-dedupe' );
#### iterDedupe( iterator\[, limit] )
Returns an [iterator][mdn-iterator-protocol] which removes consecutive duplicated values.
`javascript
var array2iterator = require( '@stdlib/array-to-iterator' );
var it = iterDedupe( array2iterator( [ 1, 1, 2, 3, 3, 3, 4, 4 ] ) );
// returns
var v = it.next().value;
// returns 1
v = it.next().value;
// returns 2
v = it.next().value;
// returns 3
v = it.next().value;
// returns 4
var bool = it.next().done;
// returns true
`
The returned [iterator][mdn-iterator-protocol] protocol-compliant object has the following properties:
- next: function which returns an [iterator][mdn-iterator-protocol] 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][mdn-iterator-protocol] is finished.
- return: function which closes an [iterator][mdn-iterator-protocol] and returns a single (optional) argument in an [iterator][mdn-iterator-protocol] protocol-compliant object.
The returned [iterator][mdn-iterator-protocol] removes consecutive duplicated values and does not return globally unique values.
`javascript
var array2iterator = require( '@stdlib/array-to-iterator' );
var it = iterDedupe( array2iterator( [ 1, 1, 2, 1, 1, 2 ] ) );
// returns
var v = it.next().value;
// returns 1
v = it.next().value;
// returns 2
v = it.next().value;
// returns 1
v = it.next().value;
// returns 2
var bool = it.next().done;
// returns true
`
To specify the number of allowed consecutive duplicated values, provide a second argument.
`javascript
var array2iterator = require( '@stdlib/array-to-iterator' );
var it = iterDedupe( array2iterator( [ 1, 1, 2, 3, 3, 3, 3, 4, 4, 4 ] ), 2 );
// returns
var v = it.next().value;
// returns 1
v = it.next().value;
// returns 1
v = it.next().value;
// returns 2
v = it.next().value;
// returns 3
v = it.next().value;
// returns 3
v = it.next().value;
// returns 4
v = it.next().value;
// returns 4
var bool = it.next().done;
// returns true
`
- NaN values are considered distinct.
`javascript
var array2iterator = require( '@stdlib/array-to-iterator' );
var it = iterDedupe( array2iterator( [ NaN, NaN, NaN, NaN ] ) );
// returns
var v = it.next().value;
// returns NaN
v = it.next().value;
// returns NaN
v = it.next().value;
// returns NaN
v = it.next().value;
// returns NaN
var bool = it.next().done;
// returns true
`
- Uniqueness is determined according to strict equality. Accordingly, objects are not checked for deep equality.
`javascript
var array2iterator = require( '@stdlib/array-to-iterator' );
var it = iterDedupe( array2iterator( [ {}, {}, {}, {} ] ) );
// returns
var v = it.next().value;
// returns {}
v = it.next().value;
// returns {}
v = it.next().value;
// returns {}
v = it.next().value;
// returns {}
var bool = it.next().done;
// returns true
`
- If an environment supports Symbol.iterator and a provided [iterator][mdn-iterator-protocol] is iterable, the returned [iterator][mdn-iterator-protocol] is iterable.
`javascript
var randi = require( '@stdlib/random-iter-discrete-uniform' );
var iterDedupe = require( '@stdlib/iter-dedupe' );
// Create a seeded iterator for generating pseudorandom integers on the interval [1,3]:
var rand = randi( 1, 3, {
'seed': 1234,
'iter': 100
});
// Create an iterator which limits "runs" to at most 3 values:
var it = iterDedupe( rand, 3 );
// Perform manual iteration...
var v;
while ( true ) {
v = it.next();
if ( v.done ) {
break;
}
console.log( v.value );
}
`
*
- [@stdlib/iter-dedupe-by][@stdlib/iter/dedupe-by]: create an iterator which removes consecutive values that resolve to the same value according to a provided function.
- [@stdlib/iter-unique][@stdlib/iter/unique]: create an iterator which returns unique values.
*
This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].
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---
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