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base/from-strided/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2023 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.
+
+-->
+
+# strided2array
+
+> Convert a strided array to a non-strided generic array.
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var strided2array = require( '@stdlib/array/base/from-strided' );
+```
+
+#### strided2array( N, x, stride, offset )
+
+Converts a strided array to a non-strided generic array.
+
+```javascript
+var x = [ 1, 2, 3, 4, 5, 6 ];
+
+var arr = strided2array( 3, x, 2, 0 );
+// returns [ 1, 3, 5 ]
+```
+
+The function accepts the following arguments:
+
+-   **N**: number of indexed elements.
+-   **x**: input array.
+-   **stride**: index stride.
+-   **offset**: index of the first indexed value in the input array.
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## Notes
+
+-   The function assumes that the input array is compatible with the specified number of elements, index stride, and index offset.
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var zeroTo = require( '@stdlib/array/base/zero-to' );
+var strided2array = require( '@stdlib/array/base/from-strided' );
+
+var x = zeroTo( 10 );
+console.log( x );
+
+var y = strided2array( 5, x, -2, x.length-1 );
+console.log( y );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- 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">
+
+</section>
+
+<!-- /.links -->

base/from-strided/benchmark/benchmark.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2023 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 isnan = require( '@stdlib/math/base/assert/is-nan' );
+var pow = require( '@stdlib/math/base/special/pow' );
+var zeroTo = require( './../../../base/zero-to' );
+var pkg = require( './../package.json' ).name;
+var strided2array = require( './../lib' );
+
+
+// FUNCTIONS //
+
+/**
+* Creates a benchmark function.
+*
+* @private
+* @param {PositiveInteger} N - number of elements
+* @returns {Function} benchmark function
+*/
+function createBenchmark( N ) {
+	var x = zeroTo( N );
+	return benchmark;
+
+	/**
+	* Benchmark function.
+	*
+	* @private
+	* @param {Benchmark} b - benchmark instance
+	*/
+	function benchmark( b ) {
+		var out;
+		var i;
+
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			out = strided2array( N, x, 1, 0 );
+			if ( isnan( out[ i%N ] ) ) {
+				b.fail( 'should not return NaN' );
+			}
+		}
+		b.toc();
+
+		if ( isnan( out[ i%N ] ) ) {
+			b.fail( 'should not return NaN' );
+		}
+		b.pass( 'benchmark finished' );
+		b.end();
+	}
+}
+
+
+// MAIN //
+
+/**
+* Main execution sequence.
+*
+* @private
+*/
+function main() {
+	var min;
+	var max;
+	var N;
+	var f;
+	var i;
+
+	min = 1; // 10^min
+	max = 6; // 10^max
+
+	for ( i = min; i <= max; i++ ) {
+		N = pow( 10, i );
+		f = createBenchmark( N );
+		bench( pkg+':len='+N, f );
+	}
+}
+
+main();

base/from-strided/docs/repl.txt

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+
+{{alias}}( N, x, stride, offset )
+    Converts a strided array to a non-strided generic array.
+
+    The function assumes that the input array is compatible with the specified
+    number of elements, index stride, and index offset.
+
+    Parameters
+    ----------
+    N: integer
+        Number of indexed elements.
+
+    x: ArrayLikeObject
+        Input array.
+
+    stride: integer
+        Index stride.
+
+    offset: integer
+        Index of the first indexed value in the input array.
+
+    Examples
+    --------
+    > var x = [ 1.0, 2.0, 3.0, 4.0 ];
+    > var y = {{alias}}( 2, x, 2, 0 )
+    [ 1.0, 3.0 ]
+
+    See Also
+    --------
+

base/from-strided/docs/types/index.d.ts

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2023 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 { Collection } from '@stdlib/types/array';
+
+/**
+* Converts a strided array to a non-strided generic array.
+*
+* ## Notes
+*
+* -   The function assumes that the input array is compatible with the specified number of elements, index stride, and index offset.
+*
+* @param N - number of indexed elements
+* @param x - input array
+* @param stride - index stride
+* @param offset - index of the first indexed value in the input array
+* @returns two-dimensional nested array
+*
+* @example
+* var x = [ 1, 2, 3, 4, 5, 6 ];
+*
+* var arr = strided2array( 3, x, 2, 0 );
+* // returns [ 1, 3, 5 ]
+*/
+declare function strided2array<T = unknown, U = T>( N: number, x: Collection<T>, stride: number, offset: number ): Array<U>;
+
+
+// EXPORTS //
+
+export = strided2array;

base/from-strided/docs/types/test.ts

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2023 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 strided2array = require( './index' );
+
+
+// TESTS //
+
+// The function returns an array...
+{
+	const x = [ 1.0, 2.0, 3.0, 4.0 ];
+
+	strided2array( x.length, x, 1, 0 ); // $ExpectType Array<number>
+}
+
+// The compiler throws an error if the function is provided a first argument which is not a number...
+{
+	const x = [ 1.0, 2.0, 3.0, 4.0 ];
+
+	strided2array( 'abc', x, 1, 0 ); // $ExpectError
+	strided2array( true, x, 1, 0 ); // $ExpectError
+	strided2array( false, x, 1, 0 ); // $ExpectError
+	strided2array( null, x, 1, 0 ); // $ExpectError
+	strided2array( [ '1' ], x, 1, 0 ); // $ExpectError
+	strided2array( {}, x, 1, 0 ); // $ExpectError
+	strided2array( ( x: number ): number => x, x, 1, 0 ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided a second argument which is not an array...
+{
+	strided2array( 10, 3.14, 1, 0 ); // $ExpectError
+	strided2array( 10, true, 1, 0 ); // $ExpectError
+	strided2array( 10, false, 1, 0 ); // $ExpectError
+	strided2array( 10, null, 1, 0 ); // $ExpectError
+	strided2array( 10, {}, 1, 0 ); // $ExpectError
+	strided2array( 10, ( x: number ): number => x, 1, 0 ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided a third argument which is not a number...
+{
+	const x = [ 1.0, 2.0, 3.0, 4.0 ];
+
+	strided2array( x.length, x, 'abc', 0 ); // $ExpectError
+	strided2array( x.length, x, true, 0 ); // $ExpectError
+	strided2array( x.length, x, false, 0 ); // $ExpectError
+	strided2array( x.length, x, null, 0 ); // $ExpectError
+	strided2array( x.length, x, [ '1' ], 0 ); // $ExpectError
+	strided2array( x.length, x, {}, 0 ); // $ExpectError
+	strided2array( x.length, x, ( x: number ): number => x, 0 ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided a fourth argument which is not a number...
+{
+	const x = [ 1.0, 2.0, 3.0, 4.0 ];
+
+	strided2array( x.length, x, 1, 'abc' ); // $ExpectError
+	strided2array( x.length, x, 1, true ); // $ExpectError
+	strided2array( x.length, x, 1, false ); // $ExpectError
+	strided2array( x.length, x, 1, null ); // $ExpectError
+	strided2array( x.length, x, 1, [ '1' ] ); // $ExpectError
+	strided2array( x.length, x, 1, {} ); // $ExpectError
+	strided2array( x.length, x, 1, ( x: number ): number => x ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided an unsupported number of arguments...
+{
+	const x = [ 1.0, 2.0, 3.0, 4.0 ];
+
+	strided2array(); // $ExpectError
+	strided2array( x.length ); // $ExpectError
+	strided2array( x.length, x ); // $ExpectError
+	strided2array( x.length, x, 1 ); // $ExpectError
+	strided2array( x.length, x, 1, 0, {} ); // $ExpectError
+}