Auto-generated commit

base/slice-from/lib/main.js

@@ -23,6 +23,7 @@
 var isNumber = require( '@stdlib/assert/is-number' ).isPrimitive;
 var args2multislice = require( '@stdlib/slice/base/args2multislice' );
 var Slice = require( '@stdlib/slice/ctor' );
+var getShape = require( './../../../base/shape' );
 var slice = require( './../../../base/slice' );
 
 
@@ -69,14 +70,22 @@ var slice = require( './../../../base/slice' );
 */
 function sliceFrom( x, start, strict, writable ) {
 	var args;
+	var sh;
 	var s;
 	var i;
 
+	sh = getShape( x );
 	args = [];
 	for ( i = 0; i < start.length; i++ ) {
 		s = start[ i ];
 		if ( isNumber( s ) && s !== 0 ) { // note: a start value equal to 0 is equivalent to `null` (i.e., including all elements along a dimension)
-			args.push( new Slice( s, null ) );
+			if ( s === sh[ i ] ) {
+				// When a starting index is one more than the last index along a dimension, create a slice for returning an empty array...
+				s -= 1;
+				args.push( new Slice( s, s ) );
+			} else {
+				args.push( new Slice( s, null ) );
+			}
 		} else {
 			args.push( null );
 		}

base/slice-from/test/test.js

@@ -188,7 +188,7 @@ tape( 'the function returns an empty array when a starting index is one more tha
 		[ null, null, null, null, 1 ]
 	];
 	for ( i = 0; i < values.length; i++ ) {
-		actual = sliceFrom( values[ i ], start[ i ], false, false );
+		actual = sliceFrom( values[ i ], start[ i ], true, false );
 		t.strictEqual( isndarrayLike( actual ), true, 'returns expected value' );
 		t.strictEqual( numel( actual.shape ), 0, 'returns expected value' );
 		t.strictEqual( actual.dtype, values[ i ].dtype, 'returns expected value' );

lib/index.js

@@ -360,6 +360,15 @@ setReadOnly( ns, 'ndsliceDimensionFrom', require( './../slice-dimension-from' )
 */
 setReadOnly( ns, 'ndsliceDimensionTo', require( './../slice-dimension-to' ) );
 
+/**
+* @name ndsliceFrom
+* @memberof ns
+* @readonly
+* @type {Function}
+* @see {@link module:@stdlib/ndarray/slice-from}
+*/
+setReadOnly( ns, 'ndsliceFrom', require( './../slice-from' ) );
+
 /**
 * @name ndsliceTo
 * @memberof ns

slice-from/README.md

@@ -0,0 +1,252 @@
+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2023 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.
+
+-->
+
+# sliceFrom
+
+> Return a read-only shifted view of an input [ndarray][@stdlib/ndarray/ctor].
+
+<!-- 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 sliceFrom = require( '@stdlib/ndarray/slice-from' );
+```
+
+#### sliceFrom( x, ...start\[, options] )
+
+Returns a **read-only** shifted view of an input [ndarray][@stdlib/ndarray/ctor].
+
+```javascript
+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 = 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][@stdlib/ndarray/ctor].
+-   **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 of `null` or `undefined` 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:
+
+1.  providing a single array of index arguments.
+2.  providing index arguments as separate arguments.
+
+The following example demonstrates each invocation style returning equivalent results.
+
+```javascript
+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 ] ]
+
+// 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`.
+
+```javascript
+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 = sliceFrom( x, null, 20, {
+    'strict': false
+});
+// returns <ndarray>
+
+sh = y.shape;
+// returns [ 3, 0 ]
+
+arr = ndarray2array( y );
+// returns []
+```
+
+</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
+
+-   An **index argument** must be either an integer, `null`, or `undefined`.
+-   The number of indices must match the number of array dimensions. Hence, if `x` is a zero-dimensional [ndarray][@stdlib/ndarray/ctor], then, if `start` is an array, `start` should not contain any index arguments. Similarly, if `x` is a one-dimensional [ndarray][@stdlib/ndarray/ctor], then, if `start` is an array, `start` should contain a single index argument. And so on and so forth.
+
+</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 sliceFrom = require( '@stdlib/ndarray/slice-from' );
+
+// 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 ] ] ]
+```
+
+</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">
+
+[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray/tree/main/ctor
+
+</section>
+
+<!-- /.links -->

slice-from/benchmark/benchmark.call_signatures.js

@@ -0,0 +1,86 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2023 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 baseEmpty = require( './../../base/empty' );
+var pkg = require( './../package.json' ).name;
+var sliceFrom = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg+'::2d,base,separate_arguments', function benchmark( b ) {
+	var values;
+	var v;
+	var i;
+
+	values = [
+		baseEmpty( 'float64', [ 2, 2 ], 'row-major' ),
+		baseEmpty( 'float32', [ 2, 2 ], 'row-major' ),
+		baseEmpty( 'int32', [ 2, 2 ], 'row-major' ),
+		baseEmpty( 'complex128', [ 2, 2 ], 'row-major' ),
+		baseEmpty( 'generic', [ 2, 2 ], 'row-major' )
+	];
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		v = sliceFrom( values[ i%values.length ], null, null );
+		if ( typeof v !== 'object' ) {
+			b.fail( 'should return an ndarray' );
+		}
+	}
+	b.toc();
+	if ( !isndarrayLike( v ) ) {
+		b.fail( 'should return an ndarray' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+'::2d,base,array', function benchmark( b ) {
+	var values;
+	var v;
+	var i;
+
+	values = [
+		baseEmpty( 'float64', [ 2, 2 ], 'row-major' ),
+		baseEmpty( 'float32', [ 2, 2 ], 'row-major' ),
+		baseEmpty( 'int32', [ 2, 2 ], 'row-major' ),
+		baseEmpty( 'complex128', [ 2, 2 ], 'row-major' ),
+		baseEmpty( 'generic', [ 2, 2 ], 'row-major' )
+	];
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		v = sliceFrom( values[ i%values.length ], [ null, null ] );
+		if ( typeof v !== 'object' ) {
+			b.fail( 'should return an ndarray' );
+		}
+	}
+	b.toc();
+	if ( !isndarrayLike( v ) ) {
+		b.fail( 'should return an ndarray' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});