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Return a read-only shifted view of an input ndarray.
import sliceFrom from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-slice-from@deno/mod.js';
Returns a read-only shifted view of an input ndarray.
import ndarray from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-ctor@deno/mod.js';
import ndarray2array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-to-array@deno/mod.js';
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 = sliceFrom( x, 1, null );
// returns <ndarray>
sh = y.shape;
// returns [ 2, 2 ]
arr = ndarray2array( y );
// returns [ [ 3.0, 4.0 ], [ 5.0, 6.0 ] ]
The function accepts the following arguments:
- x: input ndarray.
- start: an array of starting indices (inclusive) or starting indices (inclusive) as separate arguments. Each index must be either
null
,undefined
, or an integer. A value ofnull
orundefined
indicates to include all elements along a corresponding dimension. A negative integer indicates to resolve a starting index relative to the last element along a corresponding dimension, with the last element having index-1
. - options: function options.
The function supports two (mutually exclusive) means for providing index arguments:
- providing a single array of index arguments.
- providing index arguments as separate arguments.
The following example demonstrates each invocation style returning equivalent results.
import ndarray from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-ctor@deno/mod.js';
import ndarray2array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-to-array@deno/mod.js';
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 ] ]
// 1. Using an array of index arguments:
var y = sliceFrom( x, [ 1, null ] );
// returns <ndarray>
sh = y.shape;
// returns [ 2, 2 ]
arr = ndarray2array( y );
// returns [ [ 3.0, 4.0 ], [ 5.0, 6.0 ] ]
// 2. Providing separate arguments:
y = sliceFrom( x, 1, null );
// returns <ndarray>
sh = y.shape;
// returns [ 2, 2 ]
arr = ndarray2array( y );
// returns [ [ 3.0, 4.0 ], [ 5.0, 6.0 ] ]
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 index argument which exceeds array bounds. To return an empty array when an index exceeds array bounds, set the strict
option to false
.
import ndarray from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-ctor@deno/mod.js';
import ndarray2array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-to-array@deno/mod.js';
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 = sliceFrom( x, null, 20, {
'strict': false
});
// returns <ndarray>
sh = y.shape;
// returns [ 3, 0 ]
arr = ndarray2array( y );
// returns []
- An index argument must be either an integer,
null
, orundefined
. - The number of indices must match the number of array dimensions. Hence, if
x
is a zero-dimensional ndarray, then, ifstart
is an array,start
should not contain any index arguments. Similarly, ifx
is a one-dimensional ndarray, then, ifstart
is an array,start
should contain a single index argument. And so on and so forth.
import array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-array@deno/mod.js';
import ndarray2array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-to-array@deno/mod.js';
import zeroTo from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-base-zero-to@deno/mod.js';
import sliceFrom from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-slice-from@deno/mod.js';
// Create a linear ndarray buffer:
var buf = zeroTo( 27 );
// Create an ndarray:
var x = array( buf, {
'shape': [ 3, 3, 3 ]
});
// Get the last two rows of each matrix:
var y1 = sliceFrom( x, null, 1, null );
// returns <ndarray>
var a1 = ndarray2array( y1 );
// returns [ [ [ 3, 4, 5 ], [ 6, 7, 8 ] ], [ [ 12, 13, 14 ], [ 15, 16, 17 ] ], [ [ 21, 22, 23 ], [ 24, 25, 26 ] ] ]
// Get the last two rows and columns of each matrix:
var y2 = sliceFrom( x, null, 1, 1 );
// returns <ndarray>
var a2 = ndarray2array( y2 );
// returns [ [ [ 4, 5 ], [ 7, 8 ] ], [ [ 13, 14 ], [ 16, 17 ] ], [ [ 22, 23 ], [ 25, 26 ] ] ]
// Get the last two 2x2 matrices:
var y3 = sliceFrom( x, 1, 1, 1 );
// returns <ndarray>
var a3 = ndarray2array( y3 );
// returns [ [ [ 13, 14 ], [ 16, 17 ] ], [ [ 22, 23 ], [ 25, 26 ] ] ]
@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-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.
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