91 lines
2.1 KiB
JavaScript
91 lines
2.1 KiB
JavaScript
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/**
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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 isTypedArray = require( './../../is-typed-array' );
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var isArray = require( './../../is-array' );
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var isNumber = require( './../../is-number' ).isPrimitive;
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var absdiff = require( '@stdlib/math/base/utils/absolute-difference' );
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var FLOAT64_SQRT_EPS = require( '@stdlib/constants/float64/sqrt-eps' );
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// MAIN //
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/**
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* Tests if a value is an array of probabilities that sum to one.
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*
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* @param {*} v - value to test
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* @returns {boolean} boolean indicating if a value is a probability array
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*
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* @example
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* var bool = isUnityProbabilityArray( [ 0.25, 0.5, 0.25 ] );
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* // returns true
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*
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* @example
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* var bool = isUnityProbabilityArray( new Uint8Array( [ 0, 1 ] ) );
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* // returns true
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*
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* @example
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* var bool = isUnityProbabilityArray( [ 0.4, 0.4, 0.4 ] );
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* // returns false
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*
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* @example
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* var bool = isUnityProbabilityArray( [ 3.14, 0.0 ] );
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* // returns false
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*/
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function isUnityProbabilityArray( v ) {
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var sum;
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var i;
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if ( isArray( v ) ) {
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sum = 0.0;
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for ( i = 0; i < v.length; i++ ) {
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if (
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!isNumber( v[ i ] ) ||
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v[ i ] > 1.0 ||
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v[ i ] < 0.0
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) {
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return false;
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}
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sum += v[ i ];
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}
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return ( absdiff( sum, 1.0 ) <= FLOAT64_SQRT_EPS );
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}
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if ( isTypedArray( v ) ) {
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sum = 0.0;
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for ( i = 0; i < v.length; i++ ) {
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if (
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v[ i ] > 1.0 ||
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v[ i ] < 0.0
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) {
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return false;
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}
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sum += v[ i ];
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}
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return ( absdiff( sum, 1.0 ) <= FLOAT64_SQRT_EPS );
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}
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return false;
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}
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// EXPORTS //
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module.exports = isUnityProbabilityArray;
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