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About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

sliceDimension

NPM version Build Status Coverage Status

Return a view of an input ndarray when sliced along a specified dimension.

Usage

To use in Observable,

sliceDimension = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-slice-dimension@umd/browser.js' )

To vendor stdlib functionality and avoid installing dependency trees for Node.js, you can use the UMD server build:

var sliceDimension = require( 'path/to/vendor/umd/ndarray-base-slice-dimension/index.js' )

To include the bundle in a webpage,

<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-slice-dimension@umd/browser.js"></script>

If no recognized module system is present, access bundle contents via the global scope:

<script type="text/javascript">
(function () {
    window.sliceDimension;
})();
</script>

sliceDimension( x, dim, slice, strict, writable )

Returns a view of an input ndarray when sliced along a specified dimension.

var Slice = require( '@stdlib/slice-ctor' );
var ndarray = require( '@stdlib/ndarray-ctor' );
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 = x.shape;
// returns [ 3, 2 ]

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

var s = new Slice( null, null, -1 );
// returns <Slice>

var y = sliceDimension( x, 0, s, false, false );
// returns <ndarray>

sh = y.shape;
// returns [ 3, 2 ]

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

The function accepts the following arguments:

  • x: input ndarray.
  • dim: index of dimension along which to slice. 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.
  • slice: a Slice instance or an integer. If provided an integer less than zero, the corresponding element along the specified dimension is resolved relative to the last element along that dimension. For negative integers, the last element corresponds to the value -1.
  • strict: boolean indicating whether to enforce strict bounds checking.
  • writable: boolean indicating whether a returned ndarray should be writable.

Notes

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

Examples

<!DOCTYPE html>
<html lang="en">
<body>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/slice-ctor@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-array@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-to-array@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/array-base-zero-to@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-slice-dimension@umd/browser.js"></script>
<script type="text/javascript">
(function () {

// Alias `null` to allow for more compact indexing expressions:
var _ = null;

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

// Create an ndarray:
var x = array( buf, {
    'shape': [ 3, 3, 3 ]
});

// Get each matrix...
var y1 = sliceDimension( x, 0, 0, false, false );
// returns <ndarray>

var a1 = ndarray2array( y1 );
// returns [ [ 0, 1, 2 ], [ 3, 4, 5 ], [ 6, 7, 8 ] ]

var y2 = sliceDimension( x, 0, 1, false, false );
// returns <ndarray>

var a2 = ndarray2array( y2 );
// returns [ [ 9, 10, 11 ], [ 12, 13, 14 ], [ 15, 16, 17 ] ]

var y3 = sliceDimension( x, 0, 2, false, false );
// returns <ndarray>

var a3 = ndarray2array( y3 );
// returns [ [ 18, 19, 20 ], [ 21, 22, 23 ], [ 24, 25, 26 ] ]

// Reverse the matrix order:
var s = S( _, _, -1 );
var y4 = sliceDimension( x, 0, s, false, false );
// returns <ndarray>

var a4 = ndarray2array( y4 );
// returns [...]

// Get the second rows from each matrix:
var y5 = sliceDimension( x, 1, 1, false, false );
// returns <ndarray>

var a5 = ndarray2array( y5 );
// returns [ [ 3, 4, 5 ], [ 12, 13, 14 ], [ 21, 22, 23 ] ]

// Get the second columns from each matrix:
var y6 = sliceDimension( x, 2, 1, false, false );
// returns <ndarray>

var a6 = ndarray2array( y6 );
// returns [ [ 1, 4, 7 ], [ 10, 13, 16 ], [ 19, 22, 25 ] ]

})();
</script>
</body>
</html>

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.