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Add iterator utility to return unique values
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‎lib/node_modules/@stdlib/iter/unique/README.md‎

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<!--
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@license Apache-2.0
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Copyright (c) 2019 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# iterUnique
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> Create an [iterator][mdn-iterator-protocol] which returns unique values.
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<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
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<section class="intro">
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</section>
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<!-- /.intro -->
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<!-- Package usage documentation. -->
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<section class="usage">
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## Usage
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```javascript
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var iterUnique = require( '@stdlib/iter/unique' );
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```
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#### iterUnique( iterator )
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Returns an [iterator][mdn-iterator-protocol] which returns unique values.
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```javascript
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var array2iterator = require( '@stdlib/array/to-iterator' );
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var it = iterUnique( array2iterator( [ 2, 1, 1, 2, 4, 3, 4, 3 ] ) );
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// returns <Object>
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var v = it.next().value;
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// returns 2
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v = it.next().value;
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// returns 1
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v = it.next().value;
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// returns 4
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v = it.next().value;
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// returns 3
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var bool = it.next().done;
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// returns true
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```
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The returned [iterator][mdn-iterator-protocol] protocol-compliant object has the following properties:
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- **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.
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- **return**: function which closes an [iterator][mdn-iterator-protocol] and returns a single (optional) argument in an [iterator][mdn-iterator-protocol] protocol-compliant object.
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</section>
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<!-- /.usage -->
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<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="notes">
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## Notes
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- Value "uniqueness" is determined according to **strict equality**.
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- A returned [iterator][mdn-iterator-protocol] internally buffers unique values and, thus, has `O(N)` memory requirements.
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- If an environment supports `Symbol.iterator` **and** a provided [iterator][mdn-iterator-protocol] is iterable, the returned [iterator][mdn-iterator-protocol] is iterable.
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</section>
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<!-- /.notes -->
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<!-- Package usage examples. -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var discreteUniform = require( '@stdlib/random/iter/discrete-uniform' );
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var iterUnique = require( '@stdlib/iter/unique' );
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// Create a seeded iterator which can generate 1000 pseudorandom numbers:
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var rand = discreteUniform( 1, 10, {
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'seed': 1234,
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'iter': 1000
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});
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// Create an iterator which returns unique values:
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var it = iterUnique( rand );
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// Perform manual iteration...
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var v;
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while ( true ) {
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v = it.next();
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if ( v.done ) {
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break;
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}
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console.log( v.value );
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}
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```
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</section>
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<!-- /.examples -->
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<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="references">
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</section>
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<!-- /.references -->
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<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="links">
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[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol
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</section>
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<!-- /.links -->

‎lib/node_modules/@stdlib/iter/unique/benchmark/benchmark.js‎

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2019 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var bench = require( '@stdlib/bench' );
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var discreteUniform = require( '@stdlib/random/iter/discrete-uniform' );
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var isnan = require( '@stdlib/math/base/assert/is-nan' );
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var isIteratorLike = require( '@stdlib/assert/is-iterator-like' );
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var pkg = require( './../package.json' ).name;
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var iterUnique = require( './../lib' );
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// MAIN //
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bench( pkg, function benchmark( b ) {
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var rand;
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var iter;
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var i;
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rand = discreteUniform( 0, 100 );
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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iter = iterUnique( rand );
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if ( typeof iter !== 'object' ) {
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b.fail( 'should return an object' );
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}
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}
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b.toc();
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if ( !isIteratorLike( iter ) ) {
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b.fail( 'should return an iterator protocol-compliant object' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});
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bench( pkg+'::iteration', function benchmark( b ) {
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var rand;
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var iter;
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var z;
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var i;
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rand = discreteUniform( 1, 1000, {
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'iter': b.iterations
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});
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iter = iterUnique( rand );
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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z = iter.next().value;
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if ( isnan( z ) ) {
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b.fail( 'should not return NaN' );
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}
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}
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b.toc();
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if ( isnan( z ) ) {
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b.fail( 'should not return NaN' );
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}
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b.pass( 'benchmark finished' );
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b.end();
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});

‎lib/node_modules/@stdlib/iter/unique/docs/repl.txt‎

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{{alias}}( iterator )
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Returns an iterator which returns unique values.
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Value "uniqueness" is determined according to strict equality.
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A returned iterator internally buffers unique values and, thus, has O(N)
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memory requirements.
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If an environment supports Symbol.iterator and a provided iterator is
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iterable, the returned iterator is iterable.
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Parameters
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----------
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iterator: Object
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Input iterator.
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Returns
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-------
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iterator: Object
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Iterator.
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iterator.next(): Function
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Returns an iterator protocol-compliant object containing the next
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iterated value (if one exists) and a boolean flag indicating whether the
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iterator is finished.
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iterator.return( [value] ): Function
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Finishes an iterator and returns a provided value.
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Examples
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--------
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> var it1 = {{alias:@stdlib/array/to-iterator}}( [ 1, 2, 1, 2, 4 ] );
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> var it2 = {{alias}}( it1 );
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> var v = it2.next().value
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1
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> v = it2.next().value
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2
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> v = it2.next().value
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4
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> var bool = it2.next().done
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true
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See Also
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--------
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‎lib/node_modules/@stdlib/iter/unique/examples/index.js‎

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2019 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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var discreteUniform = require( '@stdlib/random/iter/discrete-uniform' );
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var iterUnique = require( './../lib' );
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// Create a seeded iterator which can generate 1000 pseudorandom numbers:
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var rand = discreteUniform( 1, 10, {
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'seed': 1234,
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'iter': 1000
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});
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// Create an iterator which returns unique values:
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var it = iterUnique( rand );
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// Perform manual iteration...
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var v;
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while ( true ) {
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v = it.next();
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if ( v.done ) {
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break;
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}
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console.log( v.value );
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}

‎lib/node_modules/@stdlib/iter/unique/lib/index.js‎

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2019 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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/**
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* Create an iterator which returns unique values.
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*
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* @module @stdlib/iter/unique
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*
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* @example
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* var array2iterator = require( '@stdlib/array/to-iterator' );
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* var iterUnique = require( '@stdlib/iter/unique' );
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*
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* var iter = iterUnique( array2iterator( [ 1, 2, 1, 2, 4 ] ) );
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*
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* var v = iter.next().value;
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* // returns 1
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*
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* v = iter.next().value;
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* // returns 2
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*
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* v = iter.next().value;
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* // returns 4
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*
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* var bool = iter.next().done;
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* // returns true
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*/
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// MODULES //
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var iterUnique = require( './main.js' );
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// EXPORTS //
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module.exports = iterUnique;

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