All files / stats/base/max-by/lib ndarray.js

98.07% Statements 102/104
96.15% Branches 25/26
100% Functions 1/1
98.07% Lines 102/104

Press n or j to go to the next uncovered block, b, p or k for the previous block.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 1052x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 17x 17x 17x 17x 17x 17x 17x 17x 2x 2x 15x 17x     17x 5x 5x 2x 2x 3x 3x 10x 17x 16x 16x 9x 9x 7x 7x 17x 1x 1x 9x 17x 23x 23x 23x 2x 2x 23x 1x 1x 23x 9x 9x 23x 8x 17x 2x 2x 2x 2x 2x  
/**
* @license Apache-2.0
*
* Copyright (c) 2020 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
 
'use strict';
 
// MODULES //
 
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
var accessors = require( './accessors.js' );
 
 
// MAIN //
 
/**
* Calculates the maximum value of a strided array via a callback function.
*
* @param {PositiveInteger} N - number of indexed elements
* @param {Collection} x - input array/collection
* @param {integer} stride - index increment
* @param {NonNegativeInteger} offset - starting index
* @param {Callback} clbk - callback
* @param {*} [thisArg] - execution context
* @returns {number} maximum value
*
* @example
* var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ];
*
* function accessor( v ) {
*     return v * 2.0;
* }
*
* var v = maxBy( x.length, x, 1, 0, accessor );
* // returns 8.0
*/
function maxBy( N, x, stride, offset, clbk, thisArg ) {
	var max;
	var ix;
	var o;
	var v;
	var i;
 
	if ( N <= 0 ) {
		return NaN;
	}
	o = arraylike2object( x );
	if ( o.accessorProtocol ) {
		return accessors( N, o, stride, offset );
	}
	if ( N === 1 || stride === 0 ) {
		v = clbk.call( thisArg, x[ 0 ], 0, 0, x );
		if ( v === void 0 ) {
			return NaN;
		}
		return v;
	}
	ix = offset;
	for ( i = 0; i < N; i++ ) {
		max = clbk.call( thisArg, x[ ix ], i, ix, x );
		if ( max !== void 0 ) {
			break;
		}
		ix += stride;
	}
	if ( i === N ) {
		return NaN;
	}
	i += 1;
	for ( i; i < N; i++ ) {
		ix += stride;
		v = clbk.call( thisArg, x[ ix ], i, ix, x );
		if ( v === void 0 ) {
			continue;
		}
		if ( isnan( v ) ) {
			return v;
		}
		if ( v > max || ( v === max && isPositiveZero( v ) ) ) {
			max = v;
		}
	}
	return max;
}
 
 
// EXPORTS //
 
module.exports = maxBy;