tabulate.js (1357B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // MAIN // 22 23 /** 24 * Creates a frequency table from an input array. 25 * 26 * @private 27 * @param {NonNegativeInteger} N - number of indexed elements 28 * @param {Collection} x - input array 29 * @param {integer} strideX - `x` stride length 30 * @param {Float64Array} y - output array 31 * @param {integer} strideY - `y` stride length 32 * @returns {Collection} output array 33 * 34 * @example 35 * var arr = [ 0, 1, 1, 0, 0, 2, 3, 5 ]; 36 * var out = [ 0, 0, 0, 0, 0, 0, 0, 0 ]; 37 * 38 * var freq = tabulate( arr.length, arr, 1, out, 1 ); 39 * // returns [ 3, 2, 1, 1, 0, 1, 0, 0 ] 40 */ 41 function tabulate( N, x, strideX, y, strideY ) { 42 var i; 43 for ( i = 0; i < N; i++ ) { 44 y[ x[ i*strideX ] * strideY ] += 1; 45 } 46 return y; 47 } 48 49 50 // EXPORTS // 51 52 module.exports = tabulate;