sliceDimensionTo

Return a read-only truncated view of an input ndarray along a specified dimension.

Installation

npm install @stdlib/ndarray-slice-dimension-to

Usage

var sliceDimensionTo = require( '@stdlib/ndarray-slice-dimension-to' );

sliceDimensionTo( x, dim, stop[, options] )

Returns a read-only truncated view of an input ndarray along a specified dimension.

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 y = sliceDimensionTo( x, 0, 2 );
// returns <ndarray>

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

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

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.
• stop: ending index (exclusive). 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.
• options: function options.

The function supports the following options:

• strict: boolean indicating whether to enforce strict bounds checking.

By default, the function throws an error when provided an ending index which exceeds array bounds. To return an empty array when an ending index exceeds array bounds, set the strict option to false.

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 y = sliceDimensionTo( x, 1, -20, {
    'strict': false
});
// returns <ndarray>

sh = y.shape;
// returns [ 3, 0 ]

arr = ndarray2array( y );
// returns []

Examples

var array = require( '@stdlib/ndarray-array' );
var ndarray2array = require( '@stdlib/ndarray-to-array' );
var zeroTo = require( '@stdlib/array-base-zero-to' );
var sliceDimensionTo = require( '@stdlib/ndarray-slice-dimension-to' );

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

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

// Get the first two rows of each matrix:
var y1 = sliceDimensionTo( x, 1, 2 );
// returns <ndarray>

var a1 = ndarray2array( y1 );
// returns [ [ [ 0, 1, 2 ], [ 3, 4, 5 ] ], [ [ 9, 10, 11 ], [ 12, 13, 14 ] ], [ [ 18, 19, 20 ], [ 21, 22, 23 ] ] ]

// Get the first columns of each matrix:
var y2 = sliceDimensionTo( x, 2, 2 );
// returns <ndarray>

var a2 = ndarray2array( y2 );
// returns [ [ [ 0, 1 ], [ 3, 4 ], [ 6, 7 ] ], [ [ 9, 10 ], [ 12, 13 ], [ 15, 16 ] ], [ [ 18, 19 ], [ 21, 22 ], [ 24, 25 ] ] ]

// Get the first two matrices:
var y3 = sliceDimensionTo( x, 0, 2 );
// returns <ndarray>

var a3 = ndarray2array( y3 );
// returns [ [ [ 0, 1, 2 ], [ 3, 4, 5 ], [ 6, 7, 8 ] ], [ [ 9, 10, 11 ], [ 12, 13, 14 ], [ 15, 16, 17 ] ] ]

See Also

• @stdlib/ndarray-array: multidimensional arrays.
• @stdlib/ndarray-ctor: multidimensional array constructor.
• @stdlib/ndarray-slice: return a read-only view of an input ndarray.
• @stdlib/ndarray-slice-dimension: return a read-only view of an input ndarray when sliced along a specified dimension.
• @stdlib/ndarray-slice-dimension-from: return a read-only shifted view of an input ndarray along a specific dimension.
• @stdlib/ndarray-slice-to: return a read-only truncated view of an input ndarray.

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.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.