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https://github.com/stdlib-js/slice-base-seq2multislice

Convert a multidimensional subsequence string to a MultiSlice object.
https://github.com/stdlib-js/slice-base-seq2multislice

base colon ellipsis javascript multiple ndarray node node-js nodejs python range sequence slice stdlib subseq subsequence

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Convert a multidimensional subsequence string to a MultiSlice object.

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README

        


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# seq2multislice

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]

> Convert a multidimensional subsequence string to a [`MultiSlice`][@stdlib/slice/multi] object.

## Installation

```bash
npm install @stdlib/slice-base-seq2multislice
```

Alternatively,

- To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).
- If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).
- For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).

The [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

## Usage

```javascript
var seq2multislice = require( '@stdlib/slice-base-seq2multislice' );
```

#### seq2multislice( str, shape, strict )

Converts a multidimensional subsequence string to a [`MultiSlice`][@stdlib/slice/multi] object, where `shape` specifies the maximum allowed slice shape.

```javascript
var s = seq2multislice( ':5', [ 10 ], false );
// returns

var s0 = s.data[ 0 ];
// returns

var v = s0.start;
// returns 0

v = s0.stop;
// returns 5

v = s0.step;
// returns 1
```

A multidimensional subsequence string is a comma-separated list of single-dimension indexing expressions (i.e., integers and/or [subsequence strings][@stdlib/slice/base/seq2slice]). For example, the following

```text
2
:
2:
:10
2:10
::-1
10:2:-1
:2:
2:10:
2::2
:10:2
:, :, :
1, 2, 3
0:10, 1:20:2, ::-1
...
:, ..., 2
```

are all valid multidimensional subsequence strings. The function returns an error object if provided an invalid subsequence string.

```javascript
var s = seq2multislice( '1:2:3:4', [ 10 ], false );
// returns { 'code': 'ERR_SLICE_INVALID_SUBSEQUENCE' }
```

When `strict` is `true`, the function returns an error object if a subsequence string resolves to a slice exceeding index bounds.

```javascript
var s = seq2multislice( '10:20', [ 10 ], true );
// returns { 'code': 'ERR_SLICE_OUT_OF_BOUNDS' }
```

A returned error object may have one of the following error codes:

- **ERR_SLICE_INVALID_SUBSEQUENCE**: a subsequence string is invalid.
- **ERR_SLICE_INVALID_INCREMENT**: a subsequence string must have a non-zero increment.
- **ERR_SLICE_OUT_OF_BOUNDS**: a subsequence string resolves to a slice exceeding index bounds.
- **ERR_SLICE_TOO_MANY_DIMENSIONS**: a subsequence string has more dimensions than the provided shape.
- **ERR_SLICE_INSUFFICIENT_DIMENSIONS**: a subsequence string has too few dimensions.
- **ERR_SLICE_INVALID_ELLIPSIS**: a subsequence string must only contain at most one ellipsis.

## Notes

- Providing a single nonnegative integer `i` as a single-dimension index indexes the same elements as the subsequence `i:i+1`.
- Providing a single negative integer `i` as a single-dimension index indexes the same elements as the subsequence `n+i:n+i+i`, where `n` is the dimension size.
- While integers index the same elements as equivalent subsequences, providing an integer as a single-dimension index indicates to reduce the number of dimensions by one (e.g., if the provided shape corresponds to an array having rank `2`, then `rank(A)-1 == rank(A['0,:'])`). In contrast, providing a subsequence indicates to retain a respective dimension (e.g., if the provided shape corresponds to an array having rank `2`, then `rank(A) == rank(A[':,:'])`).
- A multidimensional subsequence string can only contain **one** ellipsis ('...') operator. An ellipsis indicates to apply `:` to each dimension necessary to index all dimensions (e.g., if `A` has rank `4`, `A['1:, ..., 2:5'] == A['1:, :, :, 2:5']`).
- Except in the case of providing a single ellipsis, the number of single-dimension indexing expressions must equal the number of dimensions in the input shape.

## Examples

```javascript
var seq2multislice = require( '@stdlib/slice-base-seq2multislice' );

var s = seq2multislice( ':,:,:', [ 10, 10, 10 ], false );
var d = s.data;
// returns [ , , ]

s = seq2multislice( '3,2:10,:', [ 10, 10, 10 ], false );
d = s.data;
// returns [ 3, , ]

s = seq2multislice( '2,2:,-5', [ 10, 10, 10 ], false );
d = s.data;
// returns [ 2, , -5 ]

s = seq2multislice( '::-2,-1,...,:', [ 10, 10, 10, 10, 10, 10 ], false );
d = s.data;
// returns [ , -1, , , , ]

s = seq2multislice( 'foo,bar', [ 10, 10 ], false );
// returns { 'code': 'ERR_SLICE_INVALID_SUBSEQUENCE' }
```

* * *

## Notice

This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].

## Copyright

Copyright © 2016-2024. The Stdlib [Authors][stdlib-authors].

[npm-image]: http://img.shields.io/npm/v/@stdlib/slice-base-seq2multislice.svg
[npm-url]: https://npmjs.org/package/@stdlib/slice-base-seq2multislice

[test-image]: https://github.com/stdlib-js/slice-base-seq2multislice/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/slice-base-seq2multislice/actions/workflows/test.yml?query=branch:main

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/slice-base-seq2multislice/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/slice-base-seq2multislice?branch=main

[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg
[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im

[stdlib]: https://github.com/stdlib-js/stdlib

[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors

[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/slice-base-seq2multislice/tree/deno
[deno-readme]: https://github.com/stdlib-js/slice-base-seq2multislice/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/slice-base-seq2multislice/tree/umd
[umd-readme]: https://github.com/stdlib-js/slice-base-seq2multislice/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/slice-base-seq2multislice/tree/esm
[esm-readme]: https://github.com/stdlib-js/slice-base-seq2multislice/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/slice-base-seq2multislice/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/slice-base-seq2multislice/main/LICENSE

[@stdlib/slice/multi]: https://github.com/stdlib-js/slice-multi

[@stdlib/slice/base/seq2slice]: https://github.com/stdlib-js/slice-base-seq2slice