93 lines
1.9 KiB
JavaScript
93 lines
1.9 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 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 PINF = require( '@stdlib/constants/float64/pinf' );
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var NINF = require( '@stdlib/constants/float64/ninf' );
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var isnan = require( '@stdlib/math/base/assert/is-nan' );
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// MAIN //
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/**
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* Returns an accumulator function which incrementally computes a mid-range.
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*
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* @returns {Function} accumulator function
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*
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* @example
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* var accumulator = incrmidrange();
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*
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* var midrange = accumulator();
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* // returns null
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*
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* midrange = accumulator( 3.14 );
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* // returns 3.14
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*
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* midrange = accumulator( -5.0 );
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* // returns ~-0.93
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*
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* midrange = accumulator( 10.1 );
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* // returns 2.55
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*
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* midrange = accumulator();
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* // returns 2.55
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*/
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function incrmidrange() {
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var max = NINF;
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var min = PINF;
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var sum;
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return accumulator;
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/**
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* If provided a value, the accumulator function returns an updated mid-range. If not provided a value, the accumulator function returns the current mid-range.
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*
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* @private
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* @param {number} [x] - new value
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* @returns {number} mid-range
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*/
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function accumulator( x ) {
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if ( arguments.length === 0 ) {
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if ( sum === void 0 ) {
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return null;
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}
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return sum / 2.0;
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}
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if ( isnan( x ) ) {
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min = x;
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max = x;
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}
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if ( x > max ) {
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max = x;
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}
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if ( x < min ) {
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min = x;
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}
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sum = max + min;
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return sum / 2.0;
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}
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}
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// EXPORTS //
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module.exports = incrmidrange;
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