|
| 1 | +<!-- |
| 2 | +
|
| 3 | +@license Apache-2.0 |
| 4 | +
|
| 5 | +Copyright (c) 2026 The Stdlib Authors. |
| 6 | +
|
| 7 | +Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | +you may not use this file except in compliance with the License. |
| 9 | +You may obtain a copy of the License at |
| 10 | +
|
| 11 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | +
|
| 13 | +Unless required by applicable law or agreed to in writing, software |
| 14 | +distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | +See the License for the specific language governing permissions and |
| 17 | +limitations under the License. |
| 18 | +
|
| 19 | +--> |
| 20 | + |
| 21 | +# last |
| 22 | + |
| 23 | +> Return a read-only view of the last element (or subarray) along one or more [`ndarray`][@stdlib/ndarray/ctor] dimensions. |
| 24 | +
|
| 25 | +<!-- Section to include introductory text. Make sure to keep an empty line after the intro section element. --> |
| 26 | + |
| 27 | +<section class="intro"> |
| 28 | + |
| 29 | +</section> |
| 30 | + |
| 31 | +<!-- /.intro --> |
| 32 | + |
| 33 | +<!-- Package usage documentation. --> |
| 34 | + |
| 35 | +<section class="usage"> |
| 36 | + |
| 37 | +## Usage |
| 38 | + |
| 39 | +```javascript |
| 40 | +var last = require( '@stdlib/ndarray/last' ); |
| 41 | +``` |
| 42 | + |
| 43 | +#### last( x\[, options] ) |
| 44 | + |
| 45 | +Returns a read-only view of the last element (or subarray) along one or more [`ndarray`][@stdlib/ndarray/ctor] dimensions. |
| 46 | + |
| 47 | +```javascript |
| 48 | +var array = require( '@stdlib/ndarray/array' ); |
| 49 | + |
| 50 | +var x = array( [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] ); |
| 51 | +// returns <ndarray>[ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] |
| 52 | + |
| 53 | +var v = last( x ); |
| 54 | +// returns <ndarray>[ 4.0 ] |
| 55 | +``` |
| 56 | + |
| 57 | +The function accepts the following arguments: |
| 58 | + |
| 59 | +- **x**: input [`ndarray`][@stdlib/ndarray/ctor]. |
| 60 | +- **options**: function options. |
| 61 | + |
| 62 | +The function accepts the following `options`: |
| 63 | + |
| 64 | +- **dims**: list of dimensions over which to perform the operation. If a dimension index is provided as an integer less than zero, the dimension index is resolved relative to the last dimension, with the last dimension corresponding to the value `-1`. By default, the function performs the operation over all dimensions. |
| 65 | + |
| 66 | +To resolve the last element (or subarray) along one or more specific dimensions, provide a `dims` option: |
| 67 | + |
| 68 | +```javascript |
| 69 | +var array = require( '@stdlib/ndarray/array' ); |
| 70 | + |
| 71 | +var x = array( [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] ); |
| 72 | +// returns <ndarray>[ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] |
| 73 | + |
| 74 | +// Last column: |
| 75 | +var v = last( x, { |
| 76 | + 'dims': [ -1 ] |
| 77 | +}); |
| 78 | +// returns <ndarray>[ 2.0, 4.0 ] |
| 79 | + |
| 80 | +// Last row: |
| 81 | +v = last( x, { |
| 82 | + 'dims': [ -2 ] |
| 83 | +}); |
| 84 | +// returns <ndarray>[ 3.0, 4.0 ] |
| 85 | +``` |
| 86 | + |
| 87 | +</section> |
| 88 | + |
| 89 | +<!-- /.usage --> |
| 90 | + |
| 91 | +<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 92 | + |
| 93 | +<section class="notes"> |
| 94 | + |
| 95 | +## Notes |
| 96 | + |
| 97 | +- The function always returns a **read-only** view. To convert a returned view to a writable [`ndarray`][@stdlib/ndarray/ctor], copy the contents to a new [`ndarray`][@stdlib/ndarray/ctor] (e.g., via [`@stdlib/ndarray/copy`][@stdlib/ndarray/copy]). |
| 98 | +- If provided an empty `dims` array, the function returns a read-only view of the input [`ndarray`][@stdlib/ndarray/ctor]. |
| 99 | + |
| 100 | +</section> |
| 101 | + |
| 102 | +<!-- /.notes --> |
| 103 | + |
| 104 | +<!-- Package usage examples. --> |
| 105 | + |
| 106 | +<section class="examples"> |
| 107 | + |
| 108 | +## Examples |
| 109 | + |
| 110 | +<!-- eslint no-undef: "error" --> |
| 111 | + |
| 112 | +```javascript |
| 113 | +var uniform = require( '@stdlib/random/uniform' ); |
| 114 | +var ndarray2array = require( '@stdlib/ndarray/to-array' ); |
| 115 | +var last = require( '@stdlib/ndarray/last' ); |
| 116 | + |
| 117 | +var x = uniform( [ 3, 3, 3 ], -10.0, 10.0 ); |
| 118 | +console.log( ndarray2array( x ) ); |
| 119 | + |
| 120 | +// Last scalar element: |
| 121 | +var v = last( x ); |
| 122 | +console.log( v.get() ); |
| 123 | + |
| 124 | +// Last columns along the innermost dimension: |
| 125 | +v = last( x, { |
| 126 | + 'dims': [ -1 ] |
| 127 | +}); |
| 128 | +console.log( ndarray2array( v ) ); |
| 129 | + |
| 130 | +// Last matrix along the outermost dimension: |
| 131 | +v = last( x, { |
| 132 | + 'dims': [ 0 ] |
| 133 | +}); |
| 134 | +console.log( ndarray2array( v ) ); |
| 135 | +``` |
| 136 | + |
| 137 | +</section> |
| 138 | + |
| 139 | +<!-- /.examples --> |
| 140 | + |
| 141 | +<!-- 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. --> |
| 142 | + |
| 143 | +<section class="references"> |
| 144 | + |
| 145 | +</section> |
| 146 | + |
| 147 | +<!-- /.references --> |
| 148 | + |
| 149 | +<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. --> |
| 150 | + |
| 151 | +<section class="related"> |
| 152 | + |
| 153 | +</section> |
| 154 | + |
| 155 | +<!-- /.related --> |
| 156 | + |
| 157 | +<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 158 | + |
| 159 | +<section class="links"> |
| 160 | + |
| 161 | +[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/ctor |
| 162 | + |
| 163 | +[@stdlib/ndarray/copy]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/ndarray/copy |
| 164 | + |
| 165 | +<!-- <related-links> --> |
| 166 | + |
| 167 | +<!-- </related-links> --> |
| 168 | + |
| 169 | +</section> |
| 170 | + |
| 171 | +<!-- /.links --> |
0 commit comments