Feat/accessor protocol for max by

lib/node_modules/@stdlib/stats/base/max-by/README.md

@@ -49,7 +49,7 @@ The function has the following parameters:
 
 -   **N**: number of indexed elements.
 -   **x**: input [`Array`][mdn-array], [`typed array`][mdn-typed-array], or an array-like object (excluding strings and functions).
--   **stride**: index increment.
+-   **stride**: stride length.
 -   **clbk**: callback function.
 -   **thisArg**: execution context (_optional_).
 

lib/node_modules/@stdlib/stats/base/max-by/benchmark/benchmark.js

@@ -21,7 +21,8 @@
 // MODULES //
 
 var bench = require( '@stdlib/bench' );
-var randu = require( '@stdlib/random/base/randu' );
+var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
+var filledarrayBy = require( '@stdlib/array/filled-by' );
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var pow = require( '@stdlib/math/base/special/pow' );
 var pkg = require( './../package.json' ).name;
@@ -49,13 +50,7 @@ function accessor( value ) {
 * @returns {Function} benchmark function
 */
 function createBenchmark( len ) {
-	var x;
-	var i;
-
-	x = [];
-	for ( i = 0; i < len; i++ ) {
-		x.push( ( randu()*20.0 ) - 10.0 );
-	}
+	var x = filledarrayBy( len, 'float64', discreteUniform( -50, 50 ) );
 	return benchmark;
 
 	function benchmark( b ) {

lib/node_modules/@stdlib/stats/base/max-by/benchmark/benchmark.ndarray.js

@@ -21,7 +21,8 @@
 // MODULES //
 
 var bench = require( '@stdlib/bench' );
-var randu = require( '@stdlib/random/base/randu' );
+var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
+var filledarrayBy = require( '@stdlib/array/filled-by' );
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var pow = require( '@stdlib/math/base/special/pow' );
 var pkg = require( './../package.json' ).name;
@@ -49,13 +50,7 @@ function accessor( value ) {
 * @returns {Function} benchmark function
 */
 function createBenchmark( len ) {
-	var x;
-	var i;
-
-	x = [];
-	for ( i = 0; i < len; i++ ) {
-		x.push( ( randu()*20.0 ) - 10.0 );
-	}
+	var x = filledarrayBy( len, 'float64', discreteUniform( -50, 50 ) );
 	return benchmark;
 
 	function benchmark( b ) {

lib/node_modules/@stdlib/stats/base/max-by/lib/accessors.js

@@ -0,0 +1,115 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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' );
+
+
+// MAIN //
+
+/**
+* Calculates the maximum value of a strided array via a callback function.
+*
+* @param {PositiveInteger} N - number of indexed elements
+* @param {Object} x - input array object
+* @param {Array<Function>} x.accessors - array element accessors
+* @param {integer} stride - stride length
+* @param {Callback} clbk - callback
+* @param {*} [thisArg] - execution context
+* @returns {number} maximum value
+*
+* @example
+* var toAccessorArray = require( '@stdlib/array/base/to-accessor-array' );
+* var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
+*
+* var x = [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0 ];
+*
+* function accessor( v ) {
+*    return v * 2.0;
+* }
+* var v = maxBy( x.length, toAccessorArray( x ), 1, accessor );
+*
+*/
+function maxBy( N, x, stride, clbk, thisArg ) {
+	var xbuf;
+	var tmp;
+	var get;
+	var max;
+	var ix;
+	var v;
+	var i;
+
+	// Cache reference to array data
+	xbuf = x.data;
+
+	// Cache a reference to the element accessor:
+	get = x.accessors[ 0 ];
+
+	if ( N <= 0 ) {
+		return NaN;
+	}
+
+	if ( N === 1 || stride === 0 ) {
+		v = clbk.call( thisArg, x[ 0 ], 0, 0, x);
+		if ( v === void 0 ) {
+			return NaN;
+		}
+		return v;
+	}
+	if ( stride < 0 ) {
+		ix = (1-N) * stride;
+	} else {
+		ix = 0;
+	}
+	for ( i = 0; i < N; i++) {
+		tmp = get( xbuf, ix );
+		max = clbk.call( thisArg, tmp, i, ix, x);
+		if ( max !== void 0 ) {
+			break;
+		}
+		ix += stride;
+	}
+	if ( i === N) {
+		return NaN;
+	}
+	i += 1;
+	for ( i; i < N; i++) {
+		ix += stride;
+		tmp = get( xbuf, ix );
+		v = clbk.call( thisArg, tmp, 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;

lib/node_modules/@stdlib/stats/base/max-by/lib/max_by.js

@@ -22,6 +22,8 @@
 
 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 //
@@ -49,12 +51,17 @@ var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
 function maxBy( N, x, stride, 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, clbk, thisArg);
+	}
 	if ( N === 1 || stride === 0 ) {
 		v = clbk.call( thisArg, x[ 0 ], 0, 0, x );
 		if ( v === void 0 ) {

lib/node_modules/@stdlib/stats/base/max-by/lib/ndarray.js

@@ -22,6 +22,8 @@
 
 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 //
@@ -50,12 +52,17 @@ var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
 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 ) {

lib/node_modules/@stdlib/stats/base/max-by/test/test.max_by.js

@@ -25,6 +25,7 @@ var floor = require( '@stdlib/math/base/special/floor' );
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
 var Float64Array = require( '@stdlib/array/float64' );
+var toAccessorArray = require( '@stdlib/array/base/to-accessor-array' );
 var maxBy = require( './../lib/max_by.js' );
 
 
@@ -37,6 +38,15 @@ function accessor( v ) {
 	return v * 2.0;
 }
 
+function createArray( len ) {
+	var arr = [];
+	var i;
+	for ( i = 0; i < len; i++ ) {
+		arr.push(undefined);
+	}
+	return arr;
+}
+
 
 // TESTS //
 
@@ -75,11 +85,11 @@ tape( 'the function calculates the maximum value of a strided array via a callba
 	v = maxBy( x.length, x, 1, accessor );
 	t.strictEqual( isnan( v ), true, 'returns expected value' );
 
-	x = new Array( 5 ); // sparse array
+	x = createArray(5); // sparse array
 	v = maxBy( x.length, x, 1, accessor );
 	t.strictEqual( isnan( v ), true, 'returns expected value' );
 
-	x = new Array( 5 ); // sparse array
+	x = createArray(5); // sparse array
 	x[ 2 ] = 1.0;
 	v = maxBy( x.length, x, 1, accessor );
 	t.strictEqual( v, 2.0, 'returns expected value' );
@@ -111,7 +121,7 @@ tape( 'if provided an `N` parameter equal to `1`, the function returns the first
 	v = maxBy( 1, x, 1, accessor );
 	t.strictEqual( v, 2.0, 'returns expected value' );
 
-	x = new Array( 1 ); // sparse array
+	x = createArray(1); // sparse array
 
 	v = maxBy( 1, x, 1, accessor );
 	t.strictEqual( isnan( v ), true, 'returns expected value' );
@@ -142,6 +152,27 @@ tape( 'the function supports a `stride` parameter', function test( t ) {
 	t.end();
 });
 
+tape( 'the function calculates the maximum value of a strided array(accessor) via a callback function', function test( t ) {
+	var x;
+	var v;
+
+	x = [
+		1.0,  // 0
+		2.0,
+		2.0,  // 1
+		-7.0,
+		-2.0, // 2
+		3.0,
+		4.0,  // 3
+		2.0
+	];
+
+	v = maxBy( x.length, toAccessorArray( x ), 1, accessor );
+
+	t.strictEqual( v, 8.0, 'returns expected value' );
+	t.end();
+});
+
 tape( 'the function supports a negative `stride` parameter', function test( t ) {
 	var N;
 	var x;
@@ -174,7 +205,7 @@ tape( 'if provided a `stride` parameter equal to `0`, the function returns the f
 	v = maxBy( x.length, x, 0, accessor );
 	t.strictEqual( v, 2.0, 'returns expected value' );
 
-	x = new Array( 1 ); // sparse array
+	x = createArray(1); // sparse array
 
 	v = maxBy( 1, x, 0, accessor );
 	t.strictEqual( isnan( v ), true, 'returns expected value' );