time-to-botec

Benchmark sampling in different programming languages
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max_by.js (2140B)

      1 /**
      2 * @license Apache-2.0
      3 *
      4 * Copyright (c) 2020 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 // MODULES //
     22 
     23 var isnan = require( '@stdlib/math/base/assert/is-nan' );
     24 var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
     25 
     26 
     27 // MAIN //
     28 
     29 /**
     30 * Calculates the maximum value of a strided array via a callback function.
     31 *
     32 * @param {PositiveInteger} N - number of indexed elements
     33 * @param {Collection} x - input array/collection
     34 * @param {integer} stride - index increment
     35 * @param {Callback} clbk - callback
     36 * @param {*} [thisArg] - execution context
     37 * @returns {number} maximum value
     38 *
     39 * @example
     40 * var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ];
     41 *
     42 * function accessor( v ) {
     43 *     return v * 2.0;
     44 * }
     45 *
     46 * var v = maxBy( x.length, x, 1, accessor );
     47 * // returns 8.0
     48 */
     49 function maxBy( N, x, stride, clbk, thisArg ) {
     50 	var max;
     51 	var ix;
     52 	var v;
     53 	var i;
     54 
     55 	if ( N <= 0 ) {
     56 		return NaN;
     57 	}
     58 	if ( N === 1 || stride === 0 ) {
     59 		v = clbk.call( thisArg, x[ 0 ], 0, 0, x );
     60 		if ( v === void 0 ) {
     61 			return NaN;
     62 		}
     63 		return v;
     64 	}
     65 	if ( stride < 0 ) {
     66 		ix = (1-N) * stride;
     67 	} else {
     68 		ix = 0;
     69 	}
     70 	for ( i = 0; i < N; i++ ) {
     71 		max = clbk.call( thisArg, x[ ix ], i, ix, x );
     72 		if ( max !== void 0 ) {
     73 			break;
     74 		}
     75 		ix += stride;
     76 	}
     77 	if ( i === N ) {
     78 		return NaN;
     79 	}
     80 	i += 1;
     81 	for ( i; i < N; i++ ) {
     82 		ix += stride;
     83 		v = clbk.call( thisArg, x[ ix ], i, ix, x );
     84 		if ( v === void 0 ) {
     85 			continue;
     86 		}
     87 		if ( isnan( v ) ) {
     88 			return v;
     89 		}
     90 		if ( v > max || ( v === max && isPositiveZero( v ) ) ) {
     91 			max = v;
     92 		}
     93 	}
     94 	return max;
     95 }
     96 
     97 
     98 // EXPORTS //
     99 
    100 module.exports = maxBy;