feat: add ml/base/kmeans/stats/struct-factory

lib/node_modules/@stdlib/ml/base/kmeans/stats/struct-factory/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2026 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.
+
+-->
+
+# structFactory
+
+> Create a new [`struct`][@stdlib/dstructs/struct] constructor tailored to a specified floating-point data type.
+
+<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<!-- Package usage documentation. -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var structFactory = require( '@stdlib/ml/base/kmeans/stats/struct-factory' );
+```
+
+#### structFactory( dtype, k )
+
+Returns a new [`struct`][@stdlib/dstructs/struct] constructor tailored to a specified floating-point data type.
+
+```javascript
+var Struct = structFactory( 'float64', 5 );
+// returns <Function>
+
+var s = new Struct();
+// returns <Struct>
+```
+
+The function supports the following parameters:
+
+-   **dtype**: floating-point data type for storing floating-point results. Must be either `'float64'` or `'float32'`.
+-   **k**: number of centroids.
+
+</section>
+
+<!-- /.usage -->
+
+<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+## Notes
+
+-   A [`struct`][@stdlib/dstructs/struct] provides a fixed-width composite data structure for storing kmeans clustering statistics and provides an ABI-stable data layout for JavaScript-C interoperation.
+
+</section>
+
+<!-- /.notes -->
+
+<!-- Package usage examples. -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var Float64Array = require( '@stdlib/array/float64' );
+var Float32Array = require( '@stdlib/array/float32' );
+var Int32Array = require( '@stdlib/array/int32' );
+var structFactory = require( '@stdlib/ml/base/kmeans/stats/struct-factory' );
+
+var Struct = structFactory( 'float64', 2 );
+var results = new Struct({
+    'nObs': new Int32Array( [ 3, 2 ] ),
+    'sumSquaredDist': new Float64Array( [ 9.998, 11.412 ] ),
+    'meanSquaredDist': new Float64Array( [ 4.353, 2.897 ] ),
+    'stdevSquaredDist': new Float64Array( [ 1.232, 8.913 ] )
+});
+
+var str = results.toString({
+    'format': 'linear'
+});
+console.log( str );
+
+Struct = structFactory( 'float32', 2 );
+results = new Struct({
+    'nObs': new Int32Array( [ 3, 2 ] ),
+    'sumSquaredDist': new Float32Array( [ 9.998, 11.412 ] ),
+    'meanSquaredDist': new Float32Array( [ 4.353, 2.897 ] ),
+    'stdevSquaredDist': new Float32Array( [ 1.232, 8.913 ] )
+});
+
+str = results.toString({
+    'format': 'linear'
+});
+console.log( str );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="references">
+
+</section>
+
+<!-- /.references -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+</section>
+
+<!-- /.related -->
+
+<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="links">
+
+[@stdlib/dstructs/struct]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/dstructs/struct
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/ml/base/kmeans/stats/struct-factory/benchmark/benchmark.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 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 bench = require( '@stdlib/bench' );
+var isFunction = require( '@stdlib/assert/is-function' );
+var pkg = require( './../package.json' ).name;
+var factory = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+	var values;
+	var v;
+	var k;
+	var i;
+
+	values = [
+		'float64',
+		'float32'
+	];
+	k = 10;
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		v = factory( values[ i%values.length ], k );
+		if ( typeof v !== 'function' ) {
+			b.fail( 'should return a function' );
+		}
+	}
+	b.toc();
+	if ( !isFunction( v ) ) {
+		b.fail( 'should return a function' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});

lib/node_modules/@stdlib/ml/base/kmeans/stats/struct-factory/docs/repl.txt

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+
+{{alias}}( dtype, k )
+    Returns a new struct constructor tailored to a specified floating-point data
+    type.
+
+    Parameters
+    ----------
+    dtype: string
+        Floating-point data type for storing floating-point statistics.
+
+    k: integer
+        Number of centroids.
+
+    Returns
+    -------
+    fcn: Function
+        Struct constructor.
+
+    Examples
+    --------
+    > var S = {{alias}}( 'float64', 3 );
+    > var r = new S();
+    > r.toString()
+    <string>
+
+    See Also
+    --------
+

lib/node_modules/@stdlib/ml/base/kmeans/stats/struct-factory/docs/types/index.d.ts

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2026 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.
+*/
+
+// TypeScript Version: 4.1
+
+/**
+* Interface describing cluster statistics.
+*/
+interface Statistics<T> {
+	/**
+	* Number of observations in each cluster.
+	*/
+	nObs?: Int32Array;
+
+	/**
+	* Sum of squared distance from cluster centroids.
+	*/
+	sumSquaredDist?: T;
+
+	/**
+	* Mean squared distance from cluster centroids.
+	*/
+	meanSquaredDist?: T;
+
+	/**
+	* Standard deviation of squared distance from cluster centroids.
+	*/
+	stdevSquaredDist?: T;
+}
+
+/**
+* Interface describing a struct data structure.
+*/
+declare class Struct<T> {
+	/**
+	* Struct constructor.
+	*
+	* @param arg - buffer or data object
+	* @param byteOffset - byte offset
+	* @param byteLength - maximum byte length
+	* @returns struct
+	*/
+	constructor( arg?: ArrayBuffer | Statistics<T>, byteOffset?: number, byteLength?: number );
+
+	/**
+	* Number of observations in each cluster.
+	*/
+	nObs: Int32Array;
+
+	/**
+	* Sum of squared distance from cluster centroids.
+	*/
+	sumSquaredDist: T;
+
+	/**
+	* Mean squared distance from cluster centroids.
+	*/
+	meanSquaredDist: T;
+
+	/**
+	* Standard deviation of squared distance from cluster centroids.
+	*/
+	stdevSquaredDist: T;
+}
+
+/**
+* Interface defining a struct constructor which is both "newable" and "callable".
+*/
+interface StructConstructor<T> {
+	/**
+	* Struct constructor.
+	*
+	* @param arg - buffer or data object
+	* @param byteOffset - byte offset
+	* @param byteLength - maximum byte length
+	* @returns struct
+	*/
+	new( arg?: ArrayBuffer | Statistics<T>, byteOffset?: number, byteLength?: number ): Struct<T>;
+
+	/**
+	* Struct constructor.
+	*
+	* @param arg - buffer or data object
+	* @param byteOffset - byte offset
+	* @param byteLength - maximum byte length
+	* @returns struct
+	*/
+	( arg?: ArrayBuffer | Statistics<T>, byteOffset?: number, byteLength?: number ): Struct<T>;
+}
+
+/**
+* Returns a new struct constructor tailored to a specified floating-point data type.
+*
+* @param dtype - floating-point data type for storing floating-point statistics
+* @param k - number of centroids
+* @returns struct constructor
+*
+* @example
+* var Struct = structFactory( 'float64', 5 );
+* // returns <Function>
+*
+* var s = new Struct();
+* // returns <Struct>
+*/
+declare function structFactory( dtype: 'float64', k: number ): StructConstructor<Float64Array>;
+
+/**
+* Returns a new struct constructor tailored to a specified floating-point data type.
+*
+* @param dtype - floating-point data type for storing floating-point statistics
+* @param k - number of centroids
+* @returns struct constructor
+*
+* @example
+* var Struct = structFactory( 'float32', 5 );
+* // returns <Function>
+*
+* var s = new Struct();
+* // returns <Struct>
+*/
+declare function structFactory( dtype: 'float32', k: number ): StructConstructor<Float32Array>;
+
+
+// EXPORTS //
+
+export = structFactory;