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Add iterator utility to compute a moving mid-range
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‎lib/node_modules/@stdlib/stats/iter/mmidrange/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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# itermmidrange
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> Create an [iterator][mdn-iterator-protocol] which iteratively computes a moving [mid-range][mid-range].
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<section class="intro">
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The [**mid-range**][mid-range], or **mid-extreme**, is the arithmetic mean of maximum and minimum values. Accordingly, the [mid-range][mid-range] is the midpoint of the [range][range] and a measure of central tendency.
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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 itermmidrange = require( '@stdlib/stats/iter/mmidrange' );
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```
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#### itermmidrange( iterator, W )
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Returns an [iterator][mdn-iterator-protocol] which iteratively computes a moving [mid-range][mid-range]. The `W` parameter defines the number of iterated values over which to compute the moving [mid-range][mid-range].
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```javascript
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var array2iterator = require( '@stdlib/array/to-iterator' );
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var arr = array2iterator( [ 2.0, 1.0, 3.0, -7.0, -5.0 ] );
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var it = itermmidrange( arr, 3 );
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// Fill the window...
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var v = it.next().value; // [2.0]
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// returns 2.0
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v = it.next().value; // [2.0, 1.0]
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// returns 1.5
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v = it.next().value; // [2.0, 1.0, 3.0]
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// returns 2.0
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// Window begins sliding...
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v = it.next().value; // [1.0, 3.0, -7.0]
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// returns -2.0
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v = it.next().value; // [3.0, -7.0, -5.0]
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// returns -2.0
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```
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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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- If an iterated value is non-numeric (including `NaN`), the function returns `NaN` for **at least** `W-1` future invocations. If non-numeric iterated values are possible, you are advised to provide an [`iterator`][mdn-iterator-protocol] which type checks and handles non-numeric values accordingly.
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- As `W` values are needed to fill the window buffer, the first `W-1` returned values are calculated from smaller sample sizes. Until the window is full, each returned value is calculated from all previously iterated values.
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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 runif = require( '@stdlib/random/iter/uniform' );
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var itermmidrange = require( '@stdlib/stats/iter/mmidrange' );
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// Create an iterator for generating uniformly distributed pseudorandom numbers:
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var rand = runif( -10.0, 10.0, {
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'seed': 1234,
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'iter': 100
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});
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// Create an iterator for iteratively computing a moving mid-range:
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var it = itermmidrange( rand, 3 );
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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 ( typeof v.value === 'number' ) {
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console.log( 'mid-range: %d', v.value );
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}
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if ( v.done ) {
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break;
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}
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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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[range]: https://en.wikipedia.org/wiki/Range_%28statistics%29
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[mid-range]: https://en.wikipedia.org/wiki/Mid-range
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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/stats/iter/mmidrange/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 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 randu = require( '@stdlib/random/iter/randu' );
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var pkg = require( './../package.json' ).name;
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var itermmidrange = 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 = randu();
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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iter = itermmidrange( rand, 3 );
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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 iter;
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var rand;
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var v;
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var i;
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rand = randu();
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iter = itermmidrange( rand, 3 );
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b.tic();
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for ( i = 0; i < b.iterations; i++ ) {
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v = iter.next().value;
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if ( isnan( v ) ) {
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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( v ) ) {
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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/stats/iter/mmidrange/docs/repl.txt‎

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{{alias}}( iterator, W )
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Returns an iterator which iteratively computes a moving mid-range.
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The mid-range is the arithmetic mean of maximum and minimum values.
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Accordingly, the mid-range is the midpoint of the range and a measure of
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central tendency.
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The `W` parameter defines the number of iterated values over which to
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compute the moving mid-range.
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As `W` values are needed to fill the window buffer, the first `W-1` returned
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values are calculated from smaller sample sizes. Until the window is full,
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each returned value is calculated from all previously iterated values.
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If an environment supports Symbol.iterator, the returned iterator is
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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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W: integer
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Window size.
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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 arr = {{alias:@stdlib/array/to-iterator}}( [ 2.0, -5.0, 3.0, 5.0 ] );
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> var it = {{alias}}( arr, 3 );
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> var v = it.next().value
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2.0
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> v = it.next().value
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-1.5
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> v = it.next().value
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-1.0
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> v = it.next().value
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0.0
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See Also
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--------
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‎lib/node_modules/@stdlib/stats/iter/mmidrange/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 runif = require( '@stdlib/random/iter/uniform' );
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var itermmidrange = require( './../lib' );
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// Create an iterator for generating uniformly distributed pseudorandom numbers:
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var rand = runif( -10.0, 10.0, {
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'seed': 1234,
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'iter': 100
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});
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// Create an iterator for iteratively computing a moving mid-range:
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var it = itermmidrange( rand, 3 );
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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 ( typeof v.value === 'number' ) {
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console.log( 'mid-range: %d', v.value );
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}
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if ( v.done ) {
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break;
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}
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}

‎lib/node_modules/@stdlib/stats/iter/mmidrange/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 iteratively computes a moving mid-range.
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*
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* @module @stdlib/stats/iter/mmidrange
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*
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* @example
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* var runif = require( '@stdlib/random/iter/uniform' );
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* var itermmidrange = require( '@stdlib/stats/iter/mmidrange' );
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*
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* var rand = runif( -10.0, 10.0, {
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* 'iter': 100
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* });
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*
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* var it = itermmidrange( rand, 3 );
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*
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* var v = it.next().value;
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* // returns <number>
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*
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* v = it.next().value;
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* // returns <number>
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*
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* v = it.next().value;
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* // returns <number>
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*
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* // ...
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*/
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// MODULES //
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var iterator = require( './main.js' );
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// EXPORTS //
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module.exports = iterator;

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