53 lines
1.3 KiB
JavaScript
53 lines
1.3 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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// MAIN //
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/**
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* Creates a frequency table from an input array.
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*
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* @private
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* @param {NonNegativeInteger} N - number of indexed elements
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* @param {Collection} x - input array
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* @param {integer} strideX - `x` stride length
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* @param {Float64Array} y - output array
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* @param {integer} strideY - `y` stride length
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* @returns {Collection} output array
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*
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* @example
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* var arr = [ 0, 1, 1, 0, 0, 2, 3, 5 ];
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* var out = [ 0, 0, 0, 0, 0, 0, 0, 0 ];
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*
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* var freq = tabulate( arr.length, arr, 1, out, 1 );
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* // returns [ 3, 2, 1, 1, 0, 1, 0, 0 ]
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*/
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function tabulate( N, x, strideX, y, strideY ) {
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var i;
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for ( i = 0; i < N; i++ ) {
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y[ x[ i*strideX ] * strideY ] += 1;
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}
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return y;
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}
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// EXPORTS //
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module.exports = tabulate;
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