feat: add ndarray/base/reduced-shape

lib/node_modules/@stdlib/ndarray/base/reduced-shape/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.
+
+-->
+
+# reducedShape
+
+> Return a reduced shape of an [ndarray][@stdlib/ndarray/base/ctor].
+
+<!-- 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 reducedShape = require( '@stdlib/ndarray/base/reduced-shape' );
+```
+
+#### reducedShape( x, dims )
+
+Returns a reduced shape of an [ndarray][@stdlib/ndarray/base/ctor].
+
+```javascript
+var zeros = require( '@stdlib/ndarray/zeros' );
+
+var x = zeros( [ 3, 2, 3 ] );
+// returns <ndarray>
+
+var sh = reducedShape( x, [ 0, 1 ] );
+// returns [ 3 ]
+```
+
+</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">
+
+</section>
+
+<!-- /.notes -->
+
+<!-- Package usage examples. -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+<!-- eslint-disable new-cap -->
+
+```javascript
+var zeros = require( '@stdlib/ndarray/zeros' );
+var reducedShape = require( '@stdlib/ndarray/base/reduced-shape' );
+
+// Create an array:
+var x = zeros( [ 1, 2, 3, 2 ] );
+// returns <ndarray>
+
+var sh = reducedShape( x, [ 0, 1 ] );
+console.log( sh );
+// => [ 3, 2 ]
+
+sh = reducedShape( x, [ 0, 3 ] );
+console.log( sh );
+// => [ 2, 3 ]
+
+sh = reducedShape( x, [ 1, 3 ] );
+console.log( sh );
+// => [ 1, 3 ]
+```
+
+</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/ndarray/base/ctor]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/base/ctor
+
+<!-- <related-links> -->
+
+<!-- </related-links> -->
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/ndarray/base/reduced-shape/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 zeros = require( '@stdlib/ndarray/zeros' );
+var isCollection = require( '@stdlib/assert/is-collection' );
+var pkg = require( './../package.json' ).name;
+var reducedShape = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+	var values;
+	var dims;
+	var out;
+	var i;
+
+	values = [
+		zeros( [ 10, 10, 10, 1 ] ),
+		zeros( [ 5, 5, 5, 1, 1 ] ),
+		zeros( [ 3, 4, 5 ] )
+	];
+
+	dims = [
+		[ 0, 1 ],
+		[ 0, 2 ],
+		[ 1 ]
+	];
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		out = reducedShape( values[ i%values.length ], dims[ i%dims.length ] );
+		if ( typeof out !== 'object' ) {
+			b.fail( 'should return an array' );
+		}
+	}
+	b.toc();
+	if ( !isCollection( out ) ) {
+		b.fail( 'should return an array' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});

lib/node_modules/@stdlib/ndarray/base/reduced-shape/docs/repl.txt

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+
+{{alias}}( x, dims )
+    Returns a reduced shape of a provided ndarray.
+
+    Parameters
+    ----------
+    x: ndarray
+        Input ndarray.
+
+    dims: Array<integer>
+        List of dimensions to reduce.
+
+    Returns
+    -------
+    out: Array<integer>
+        Reduced shape.
+
+    Examples
+    --------
+    > var out = {{alias}}( {{alias:@stdlib/ndarray/zeros}}( [ 1, 2, 3, 2 ] ), [ 0, 1 ] )
+    [ 3, 2 ]
+
+    See Also
+    --------
+

lib/node_modules/@stdlib/ndarray/base/reduced-shape/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
+
+/// <reference types="@stdlib/types"/>
+
+import { ndarray, Shape } from '@stdlib/types/ndarray';
+import { Collection } from '@stdlib/types/array';
+
+/**
+* Returns a reduced shape of a provided ndarray.
+*
+* @param x - input ndarray
+* @param dims - list of dimensions to reduce
+* @returns reduced shape
+*
+* @example
+* var zeros = require( '@stdlib/ndarray/zeros' );
+*
+* var x = zeros( [ 1, 2, 3, 2 ] );
+* // returns <ndarray>
+*
+* var sh = reducedShape( x, [ 0, 1 ] );
+* // returns [ 3, 2 ]
+*/
+declare function reducedShape( x: ndarray, dims: Collection<number> ): Shape;
+
+
+// EXPORTS //
+
+export = reducedShape;

lib/node_modules/@stdlib/ndarray/base/reduced-shape/docs/types/test.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.
+*/
+
+import zeros = require( '@stdlib/ndarray/zeros' );
+import reducedShape = require( './index' );
+
+
+// TESTS //
+
+// The function returns a shape array...
+{
+	reducedShape( zeros( [ 3, 2, 3 ] ), [ 0, 1 ] ); // $ExpectType Shape
+}
+
+// The compiler throws an error if the function is provided a first argument which is not an ndarray...
+{
+	reducedShape( '10', [ 0 ] ); // $ExpectError
+	reducedShape( true, [ 0 ] ); // $ExpectError
+	reducedShape( false, [ 0 ] ); // $ExpectError
+	reducedShape( 10, [ 0 ] ); // $ExpectError
+	reducedShape( null, [ 0 ] ); // $ExpectError
+	reducedShape( undefined, [ 0 ] ); // $ExpectError
+	reducedShape( [], [ 0 ] ); // $ExpectError
+	reducedShape( {}, [ 0 ] ); // $ExpectError
+	reducedShape( ( x: number ): number => x, [ 0 ] ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided a second argument which is not an array-like object of numbers...
+{
+	reducedShape( zeros( [ 3, 2, 3 ] ), '10' ); // $ExpectError
+	reducedShape( zeros( [ 3, 2, 3 ] ), true ); // $ExpectError
+	reducedShape( zeros( [ 3, 2, 3 ] ), false ); // $ExpectError
+	reducedShape( zeros( [ 3, 2, 3 ] ), 10 ); // $ExpectError
+	reducedShape( zeros( [ 3, 2, 3 ] ), null ); // $ExpectError
+	reducedShape( zeros( [ 3, 2, 3 ] ), undefined ); // $ExpectError
+	reducedShape( zeros( [ 3, 2, 3 ] ), {} ); // $ExpectError
+	reducedShape( zeros( [ 3, 2, 3 ] ), ( x: number ): number => x ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided an unsupported number of arguments...
+{
+	reducedShape(); // $ExpectError
+	reducedShape( zeros( [ 3, 2, 3 ] ) ); // $ExpectError
+	reducedShape( zeros( [ 3, 2, 3 ] ), [ 0 ], {} ); // $ExpectError
+}

lib/node_modules/@stdlib/ndarray/base/reduced-shape/examples/index.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';
+
+var zeros = require( '@stdlib/ndarray/zeros' );
+var reducedShape = require( './../lib' );
+
+// Create an array:
+var x = zeros( [ 1, 2, 3, 2 ] );
+// returns <ndarray>
+
+var sh = reducedShape( x, [ 0, 1 ] );
+console.log( sh );
+// => [ 3, 2 ]
+
+sh = reducedShape( x, [ 0, 3 ] );
+console.log( sh );
+// => [ 2, 3 ]
+
+sh = reducedShape( x, [ 1, 3 ] );
+console.log( sh );
+// => [ 1, 3 ]