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feat: add ndarray/base/shift #8118

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kgryte merged 8 commits into stdlib-js:develop from headlessNode:ndarray-base-shift
Sep 25, 2025
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154 changes: 154 additions & 0 deletions lib/node_modules/@stdlib/ndarray/base/shift/README.md
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<!--

@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.

-->

# shift

> Return an array containing a truncated view of an input ndarray and a view of the first element(s) along a specified dimension.

<!-- 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 shift = require( '@stdlib/ndarray/base/shift' );
```

#### shift( x, dim, writable )

Returns an array containing a truncated view of an input ndarray and a view of the first element(s) along a specified dimension.

```javascript
var ndarray = require( '@stdlib/ndarray/ctor' );
var getShape = require( '@stdlib/ndarray/shape' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );

var buffer = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
var shape = [ 3, 2 ];
var strides = [ 2, 1 ];
var offset = 0;

var x = ndarray( 'generic', buffer, shape, strides, offset, 'row-major' );
// returns <ndarray>

var sh = getShape( x );
// returns [ 3, 2 ]

var arr = ndarray2array( x );
// returns [ [ 1.0, 2.0 ], [ 3.0, 4.0 ], [ 5.0, 6.0 ] ]

var y = shift( x, 0, false );
// returns [ <ndarray>, <ndarray> ]

arr = ndarray2array( y[ 0 ] );
// returns [ [ 3.0, 4.0 ], [ 5.0, 6.0 ] ]

arr = ndarray2array( y[ 1 ] );
// returns [ [ 1.0, 2.0 ] ]
```

The function accepts the following arguments:

- **x**: input ndarray.
- **dim**: dimension along which to perform the operation. If provided an integer less than zero, the dimension index is resolved relative to the last dimension, with the last dimension corresponding to the value `-1`.
- **writable**: boolean indicating whether a returned ndarray should be writable.

</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

- The `writable` parameter **only** applies to ndarray constructors supporting **read-only** instances.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var array = require( '@stdlib/ndarray/array' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );
var zeroTo = require( '@stdlib/array/base/zero-to' );
var shift = require( '@stdlib/ndarray/base/shift' );

// Create a linear ndarray buffer:
var buf = zeroTo( 27 );

// Create an ndarray which is a stack of three 3x3 matrices:
var x = array( buf, {
'shape': [ 3, 3, 3 ]
});

// Remove the first row from each matrix:
var y = shift( x, 1, false );
// returns [ <ndarray>, <ndarray> ]

console.log( ndarray2array( y[ 0 ] ) );
console.log( ndarray2array( y[ 1 ] ) );
```

</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">

</section>

<!-- /.links -->
190 changes: 190 additions & 0 deletions lib/node_modules/@stdlib/ndarray/base/shift/benchmark/benchmark.js
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/**
* @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 bench = require( '@stdlib/bench' );
var isndarrayLike = require( '@stdlib/assert/is-ndarray-like' );
var empty = require( '@stdlib/ndarray/empty' );
var pkg = require( './../package.json' ).name;
var shift = require( './../lib' );


// MAIN //

bench( pkg+'::1d', function benchmark( b ) {
var values;
var v;
var i;

/* eslint-disable object-curly-newline, stdlib/line-closing-bracket-spacing */

values = [
empty( [ 2 ], { 'dtype': 'float64' } ),
empty( [ 2 ], { 'dtype': 'float32' } ),
empty( [ 2 ], { 'dtype': 'int32' } ),
empty( [ 2 ], { 'dtype': 'complex128' } ),
empty( [ 2 ], { 'dtype': 'generic' } )
];

/* eslint-enable object-curly-newline, stdlib/line-closing-bracket-spacing */

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
v = shift( values[ i%values.length ], 0, false );
if ( typeof v !== 'object' ) {
b.fail( 'should return an array of ndarrays' );
}
}
b.toc();
if ( !isndarrayLike( v[0] ) || !isndarrayLike( v[1] ) ) {
b.fail( 'should return an array of ndarrays' );
}
b.pass( 'benchmark finished' );
b.end();
});

bench( pkg+'::2d', function benchmark( b ) {
var values;
var v;
var i;

/* eslint-disable object-curly-newline, stdlib/line-closing-bracket-spacing */

values = [
empty( [ 2, 2 ], { 'dtype': 'float64' } ),
empty( [ 2, 2 ], { 'dtype': 'float32' } ),
empty( [ 2, 2 ], { 'dtype': 'int32' } ),
empty( [ 2, 2 ], { 'dtype': 'complex128' } ),
empty( [ 2, 2 ], { 'dtype': 'generic' } )
];

/* eslint-enable object-curly-newline, stdlib/line-closing-bracket-spacing */

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
v = shift( values[ i%values.length ], 0, false );
if ( typeof v !== 'object' ) {
b.fail( 'should return an array of ndarrays' );
}
}
b.toc();
if ( !isndarrayLike( v[0] ) || !isndarrayLike( v[1] ) ) {
b.fail( 'should return an array of ndarrays' );
}
b.pass( 'benchmark finished' );
b.end();
});

bench( pkg+'::3d', function benchmark( b ) {
var values;
var v;
var i;

/* eslint-disable object-curly-newline, stdlib/line-closing-bracket-spacing */

values = [
empty( [ 2, 2, 2 ], { 'dtype': 'float64' } ),
empty( [ 2, 2, 2 ], { 'dtype': 'float32' } ),
empty( [ 2, 2, 2 ], { 'dtype': 'int32' } ),
empty( [ 2, 2, 2 ], { 'dtype': 'complex128' } ),
empty( [ 2, 2, 2 ], { 'dtype': 'generic' } )
];

/* eslint-enable object-curly-newline, stdlib/line-closing-bracket-spacing */

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
v = shift( values[ i%values.length ], 0, false );
if ( typeof v !== 'object' ) {
b.fail( 'should return an array of ndarrays' );
}
}
b.toc();
if ( !isndarrayLike( v[0] ) || !isndarrayLike( v[1] ) ) {
b.fail( 'should return an array of ndarrays' );
}
b.pass( 'benchmark finished' );
b.end();
});

bench( pkg+'::4d', function benchmark( b ) {
var values;
var v;
var i;

/* eslint-disable object-curly-newline, stdlib/line-closing-bracket-spacing */

values = [
empty( [ 2, 2, 2, 2 ], { 'dtype': 'float64' } ),
empty( [ 2, 2, 2, 2 ], { 'dtype': 'float32' } ),
empty( [ 2, 2, 2, 2 ], { 'dtype': 'int32' } ),
empty( [ 2, 2, 2, 2 ], { 'dtype': 'complex128' } ),
empty( [ 2, 2, 2, 2 ], { 'dtype': 'generic' } )
];

/* eslint-enable object-curly-newline, stdlib/line-closing-bracket-spacing */

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
v = shift( values[ i%values.length ], 0, false );
if ( typeof v !== 'object' ) {
b.fail( 'should return an array of ndarrays' );
}
}
b.toc();
if ( !isndarrayLike( v[0] ) || !isndarrayLike( v[1] ) ) {
b.fail( 'should return an array of ndarrays' );
}
b.pass( 'benchmark finished' );
b.end();
});

bench( pkg+'::5d', function benchmark( b ) {
var values;
var v;
var i;

/* eslint-disable object-curly-newline, stdlib/line-closing-bracket-spacing */

values = [
empty( [ 2, 2, 2, 2, 2 ], { 'dtype': 'float64' } ),
empty( [ 2, 2, 2, 2, 2 ], { 'dtype': 'float32' } ),
empty( [ 2, 2, 2, 2, 2 ], { 'dtype': 'int32' } ),
empty( [ 2, 2, 2, 2, 2 ], { 'dtype': 'complex128' } ),
empty( [ 2, 2, 2, 2, 2 ], { 'dtype': 'generic' } )
];

/* eslint-enable object-curly-newline, stdlib/line-closing-bracket-spacing */

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
v = shift( values[ i%values.length ], 0, false );
if ( typeof v !== 'object' ) {
b.fail( 'should return an array of ndarrays' );
}
}
b.toc();
if ( !isndarrayLike( v[0] ) || !isndarrayLike( v[1] ) ) {
b.fail( 'should return an array of ndarrays' );
}
b.pass( 'benchmark finished' );
b.end();
});
39 changes: 39 additions & 0 deletions lib/node_modules/@stdlib/ndarray/base/shift/docs/repl.txt
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{{alias}}( x, dim, writable )
Returns an array containing a truncated view of an input ndarray and a view
of the first element(s) along a specified dimension.

Parameters
----------
x: ndarray
Input array.

dim: integer
Dimension along which to perform the operation. If provided an integer
less than zero, the dimension index is resolved relative to the last
dimension, with the last dimension corresponding to the value `-1`.

writable: boolean
Boolean indicating whether a returned ndarray should be writable. This
parameter only applies to ndarray constructors which support read-only
instances.

Returns
-------
out: Array<ndarray>
An array containing a truncated view of an input ndarray and a view of
the first element(s) along a specified dimension.

Examples
--------
> var x = {{alias:@stdlib/ndarray/array}}( [ [ 1, 2 ], [ 3, 4 ] ] )
<ndarray>
> var y = {{alias}}( x, 1, false )
[ <ndarray>, <ndarray> ]
> {{alias:@stdlib/ndarray/to-array}}( y[0] )
[ [ 2 ], [ 4 ] ]
> {{alias:@stdlib/ndarray/to-array}}( y[1] )
[ [ 1 ], [ 3 ] ]

See Also
--------
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