iterDedupe

Create an iterator which removes consecutive duplicated values.

Usage

var iterDedupe = require( '@stdlib/iter/dedupe' );

iterDedupe( iterator[, limit] )

Returns an iterator which removes consecutive duplicated values.

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

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

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 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 returned iterator removes consecutive duplicated values and does not return globally unique values.

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

var it = iterDedupe( array2iterator( [ 1, 1, 2, 1, 1, 2 ] ) );
// returns <Object>

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.

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

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

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

Notes

• NaN values are considered distinct.

  var array2iterator = require( '@stdlib/array/to-iterator' );
  
  var it = iterDedupe( array2iterator( [ NaN, NaN, NaN, NaN ] ) );
  // returns <Object>
  
  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.

  var array2iterator = require( '@stdlib/array/to-iterator' );
  
  var it = iterDedupe( array2iterator( [ {}, {}, {}, {} ] ) );
  // returns <Object>
  
  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 is iterable, the returned iterator is iterable.

Examples

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 );
}

---

See Also

• @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: create an iterator which returns unique values.