145 lines
3.2 KiB
JavaScript
145 lines
3.2 KiB
JavaScript
/**
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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 setReadOnly = require( '@stdlib/utils/define-nonenumerable-read-only-property' );
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var isIteratorLike = require( '@stdlib/assert/is-iterator-like' );
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var isFunction = require( '@stdlib/assert/is-function' );
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var hasOwnProp = require( '@stdlib/assert/has-own-property' );
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var iteratorSymbol = require( '@stdlib/symbol/iterator' );
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var incrmeanabs2 = require( './../../../incr/meanabs2' );
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// MAIN //
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/**
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* Returns an iterator which iteratively computes a cumulative arithmetic mean of squared absolute values.
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*
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* @param {Iterator} iterator - input iterator
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* @throws {TypeError} must provide an iterator
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* @returns {Iterator} iterator
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*
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* @example
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* var runif = require( '@stdlib/random/iter/uniform' );
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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 = itercumeanabs2( rand );
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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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function itercumeanabs2( iterator ) {
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var iter;
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var FLG;
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var acc;
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if ( !isIteratorLike( iterator ) ) {
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throw new TypeError( 'invalid argument. Must provide an iterator. Value: `' + iterator + '`.' );
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}
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acc = incrmeanabs2();
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// Create an iterator protocol-compliant object:
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iter = {};
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setReadOnly( iter, 'next', next );
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setReadOnly( iter, 'return', end );
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// If an environment supports `Symbol.iterator`, make the iterator iterable:
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if ( iteratorSymbol && isFunction( iterator[ iteratorSymbol ] ) ) {
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setReadOnly( iter, iteratorSymbol, factory );
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}
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return iter;
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/**
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* Returns an iterator protocol-compliant object containing the next iterated value.
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*
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* @private
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* @returns {Object} iterator protocol-compliant object
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*/
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function next() {
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var out;
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var v;
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if ( FLG ) {
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return {
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'done': true
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};
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}
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out = {};
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v = iterator.next();
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if ( typeof v.value === 'number' ) {
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out.value = acc( v.value );
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} else if ( hasOwnProp( v, 'value' ) ) {
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out.value = acc( NaN );
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}
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if ( v.done ) {
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FLG = true;
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out.done = true;
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} else {
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out.done = false;
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}
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return out;
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}
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/**
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* Finishes an iterator.
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*
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* @private
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* @param {*} [value] - value to return
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* @returns {Object} iterator protocol-compliant object
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*/
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function end( value ) {
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FLG = true;
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if ( arguments.length ) {
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return {
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'value': value,
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'done': true
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};
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}
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return {
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'done': true
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};
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}
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/**
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* Returns a new iterator.
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*
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* @private
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* @returns {Iterator} iterator
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*/
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function factory() {
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return itercumeanabs2( iterator[ iteratorSymbol ]() );
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}
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}
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// EXPORTS //
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module.exports = itercumeanabs2;
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