feat: add `stats/strided/selmax` by iampratik13 · Pull Request #11701 · stdlib-js/stdlib

iampratik13 · 2026-04-21T18:50:53Z

Resolves none.

Description

What is the purpose of this pull request?

This pull request:

feat: add stats/strided/selmax

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

none

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

No.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

Yes
No

If you answered "yes" above, how did you use AI assistance?

Code generation (e.g., when writing an implementation or fixing a bug)
Test/benchmark generation
Documentation (including examples)
Research and understanding

Disclosure

If you answered "yes" to using AI assistance, please provide a short disclosure indicating how you used AI assistance. This helps reviewers determine how much scrutiny to apply when reviewing your contribution. Example disclosures: "This PR was written primarily by Claude Code." or "I consulted ChatGPT to understand the codebase, but the proposed changes were fully authored manually by myself.".

@stdlib-js/reviewers

stdlib-bot · 2026-04-21T18:53:46Z

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/strided/selmax	$\color{green}328/328$ $\color{green}+0.00%$	$\color{green}44/44$ $\color{green}+0.00%$	$\color{green}3/3$ $\color{green}+0.00%$	$\color{green}328/328$ $\color{green}+0.00%$

The above coverage report was generated for the changes in this PR.

iampratik13 · 2026-04-21T19:09:31Z

/stdlib merge

iampratik13 · 2026-04-21T19:19:13Z

/stdlib update-copyright-years

kgryte · 2026-04-23T09:50:33Z

+/**
+* Mask array.
+*/
+type MaskArray = NumericArray | Collection<number> | AccessorArrayLike<number>;


This isn't correct. For the "generic" API, we simply mask based on truthiness.

Suggested change

type MaskArray = NumericArray | Collection<number> | AccessorArrayLike<number>;

type MaskArray = Collection<unknown> | AccessorArrayLike<unknown>;

kgryte · 2026-04-23T09:50:58Z

+	selmax( x.length, x, ( x: number ): number => x, mask, 1 ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided a fourth argument which is not a numeric array...


Suggested change

// The compiler throws an error if the function is provided a fourth argument which is not a numeric array...

// The compiler throws an error if the function is provided a fourth argument which is not an array...

kgryte · 2026-04-23T09:51:30Z

+	selmax.ndarray( x.length, x, 1, ( x: number ): number => x, mask, 1, 0 ); // $ExpectError
+}
+
+// The compiler throws an error if the `ndarray` method is provided a fifth argument which is not a numeric array...


Suggested change

// The compiler throws an error if the `ndarray` method is provided a fifth argument which is not a numeric array...

// The compiler throws an error if the `ndarray` method is provided a fifth argument which is not an array...

kgryte · 2026-04-23T09:53:10Z

+    strideX: integer
+        Stride length for `x`.
+
+    mask: Array<number>|TypedArray


Suggested change

mask: Array<number>|TypedArray

mask: Array|TypedArray

kgryte · 2026-04-23T09:53:28Z

+    offsetX: integer
+        Starting index for `x`.
+
+    mask: Array<number>|TypedArray


Suggested change

mask: Array<number>|TypedArray

mask: Array|TypedArray

kgryte · 2026-04-23T09:55:13Z

+* @param {PositiveInteger} N - number of indexed elements
+* @param {NumericArray} x - input array
+* @param {integer} strideX - `x` stride length
+* @param {NumericArray} mask - mask array


Suggested change

* @param {NumericArray} mask - mask array

* @param {Collection} mask - mask array

kgryte · 2026-04-23T09:55:23Z

+* @param {NumericArray} x - input array
+* @param {integer} strideX - stride length for `x`
+* @param {NonNegativeInteger} offsetX - starting index for `x`
+* @param {NumericArray} mask - mask array


Suggested change

* @param {NumericArray} mask - mask array

* @param {Collection} mask - mask array

kgryte · 2026-04-23T09:58:45Z

+var mask0 = new BooleanArray([
+    true, true, true, true, true, true, false, false
+]);


Suggested change

var mask0 = new BooleanArray([

true, true, true, true, true, true, false, false

]);

var mask0 = new BooleanArray( [ true, true, true, true, true, true, false, false ] );

No splitting over multiple lines like this.

kgryte · 2026-04-23T09:58:52Z

+
+Note that indexing is relative to the first index. To introduce offsets, use [`typed array`][mdn-typed-array] views.
+
+<!-- eslint-disable stdlib/capitalized-comments -->


Suggested change

kgryte · 2026-04-23T09:59:32Z

+
+* * *
+
+## See Also
+
+-   <span class="package-name">[`@stdlib/stats/strided/max`][@stdlib/stats/strided/max]</span><span class="delimiter">: </span><span class="description">calculate the maximum value of a strided array.</span>
+-   <span class="package-name">[`@stdlib/stats/strided/mskmax`][@stdlib/stats/strided/mskmax]</span><span class="delimiter">: </span><span class="description">calculate the maximum value of a strided array according to a mask.</span>
+-   <span class="package-name">[`@stdlib/stats/strided/nanmax`][@stdlib/stats/strided/nanmax]</span><span class="delimiter">: </span><span class="description">calculate the maximum value of a strided array, ignoring NaN values.</span>


Suggested change

* * *

## See Also

- [`@stdlib/stats/strided/max`][@stdlib/stats/strided/max]: calculate the maximum value of a strided array.

- [`@stdlib/stats/strided/mskmax`][@stdlib/stats/strided/mskmax]: calculate the maximum value of a strided array according to a mask.

- [`@stdlib/stats/strided/nanmax`][@stdlib/stats/strided/nanmax]: calculate the maximum value of a strided array, ignoring NaN values.

kgryte · 2026-04-23T09:59:43Z

+[@stdlib/stats/strided/max]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/strided/max
+
+[@stdlib/stats/strided/mskmax]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/strided/mskmax
+
+[@stdlib/stats/strided/nanmax]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/strided/nanmax
+


Suggested change

[@stdlib/stats/strided/max]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/strided/max

[@stdlib/stats/strided/mskmax]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/strided/mskmax

[@stdlib/stats/strided/nanmax]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/strided/nanmax

kgryte

For the most part, this is coming along. One thing that should be changed throughout is that mask should be a boolean array. So, instead of

var mask = bernoulli( x.length, 0.8, {
    'dtype': 'generic'
});

do

var mask = new BooleanArray( bernoulli( x.length, 0.8 ) );

Instead of

var mask = [ 1, 1, 0, 1 ];

do

var mask = [ true, true, false, true ];

Otherwise, your text which states that an element is only considered valid if a mask element is true is inconsistent with the examples, which are primarily showing numeric arrays.

It is fine, if operationally within this package, we accept non-boolean arrays, but all of our examples and docs should use boolean arrays or generic arrays containing booleans in order to communicate user expectation.

feat: add stats/strided/selmax

19e6a35

iampratik13 requested a review from a team April 21, 2026 18:50

stdlib-bot added Statistics Issue or pull request related to statistical functionality. Needs Review A pull request which needs code review. labels Apr 21, 2026

stdlib-bot added bot: In Progress Pull request is currently awaiting automation. and removed bot: In Progress Pull request is currently awaiting automation. labels Apr 21, 2026

kgryte added Feature Issue or pull request for adding a new feature. difficulty: 2 May require some initial design or R&D, but should be straightforward to resolve and/or implement. review: 5 and removed Needs Review A pull request which needs code review. labels Apr 23, 2026

kgryte reviewed Apr 23, 2026

View reviewed changes

kgryte requested changes Apr 23, 2026

View reviewed changes

kgryte added Needs Changes Pull request which needs changes before being merged. review: 2 and removed review: 5 labels Apr 23, 2026

chore: suggested changes

6f347cc

iampratik13 force-pushed the feat/add-stats-strided-selmax branch from 454641e to 6f347cc Compare April 25, 2026 06:35

iampratik13 marked this pull request as draft April 25, 2026 06:39

	type MaskArray = NumericArray \| Collection<number> \| AccessorArrayLike<number>;
	type MaskArray = Collection<unknown> \| AccessorArrayLike<unknown>;

	// The compiler throws an error if the function is provided a fourth argument which is not a numeric array...
	// The compiler throws an error if the function is provided a fourth argument which is not an array...

	// The compiler throws an error if the `ndarray` method is provided a fifth argument which is not a numeric array...
	// The compiler throws an error if the `ndarray` method is provided a fifth argument which is not an array...

	* @param {NumericArray} mask - mask array
	* @param {Collection} mask - mask array


		Note that indexing is relative to the first index. To introduce offsets, use [`typed array`][mdn-typed-array] views.

		<!-- eslint-disable stdlib/capitalized-comments -->

Uh oh!

Conversation

iampratik13 commented Apr 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Description

Related Issues

Questions

Other

Checklist

AI Assistance

Disclosure

Uh oh!

stdlib-bot commented Apr 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Coverage Report

Uh oh!

iampratik13 commented Apr 21, 2026

Uh oh!

iampratik13 commented Apr 21, 2026

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

kgryte left a comment

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

iampratik13 commented Apr 21, 2026 •

edited

Loading

stdlib-bot commented Apr 21, 2026 •

edited

Loading