feat: add `stats/incr/nanwmean` by Arjan-P · Pull Request #13609 · stdlib-js/stdlib

Arjan-P · 2026-07-22T08:24:47Z

Description

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This pull request:

add incremental accumulators for handling NaN values in stats/incr/nanwmean

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This pull request has the following related issues:

[RFC]: add stats/incr/nanwmean #5628

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Generated package.json, repl.txt from gemini

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stdlib-bot · 2026-07-22T08:28:48Z

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/nanwmean	$\\color{green}174/174$ $\\color{green}+0.00\\%$	$\\color{green}9/9$ $\\color{green}+0.00\\%$	$\\color{green}2/2$ $\\color{green}+0.00\\%$	$\\color{green}174/174$ $\\color{green}+0.00\\%$

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

Neerajpathak07 · 2026-07-22T12:43:44Z

/stdlib update-copyright-years

Neerajpathak07

@Arjan-P Thanks for the PR!! Left out a few comments. Commonly we want to prevent a straight away copy-paste between subsequent packages and think a bit more on what is the true intention and nature of nanwmean being added here.

Neerajpathak07 · 2026-07-22T13:00:35Z

+*
+* ## Notes
+*
+* -   If provided `NaN` or a value which, when used in computations, results in `NaN`, the accumulated value is `NaN` for all future invocations.


Copied from incr/wmean, it's the opposite of what nanwmean does (NaN is ignored). Sibling incr/nanewmean omits this note.

Neerajpathak07 · 2026-07-22T13:00:38Z

+type accumulator = ( x?: number, w?: number ) => number | null;
+
+/**
+* Returns an accumulator function which incrementally computes a weighted arithmetic mean.


Should read "... weighted arithmetic mean, ignoring NaN values." to match nanewmean and the module description.

Neerajpathak07 · 2026-07-22T13:00:42Z

+* limitations under the License.
+*/
+
+import incrwmean = require( './index' );


incorrect package name. Copy paste error from incrwmean

Should be updated below as well!!!

Neerajpathak07 · 2026-07-22T13:01:07Z

+// MAIN //
+
+/**
+* Returns an accumulator function which incrementally computes a weighted arithmetic mean, ignoring `NaN` parameters.


package.json, repl.txt, and sibling packages say "ignoring NaN values". Let's Align here on "values".

Neerajpathak07 · 2026-07-22T13:01:10Z

+/**
+* Returns an accumulator function which incrementally computes a weighted arithmetic mean, ignoring `NaN` parameters.
+*
+* ## Method


The full TeX derivation is duplicated from incr/wmean, which this package merely wraps it will drift out of sync. incr/nanewmean keeps a one-line description; recommend trimming to that plus a NaN args are ignored note.

Neerajpathak07 · 2026-07-22T13:03:01Z

+		if ( isnan( x ) || isnan( w ) ) {
+			return acc();


Suggested change

if ( isnan( x ) || isnan( w ) ) {

return acc();

if ( arguments.length < 2 || isnan( x ) || isnan( w ) ) {

return acc();

Calling acc( 2.0 ) with no weight leaves w === undefined, isnan( undefined ) is false, so this guard is bypassed and acc( 2.0, undefined ) corrupts wsum/mu to NaN for every subsequent call unrecoverable, and exactly what a nan-accumulator should prevent.

Neerajpathak07 · 2026-07-22T13:03:16Z

+		w = data[ i ].w;
+		expected = data[ i ].mean;
+		actual = acc( x, w );
+		t.strictEqual( isAlmostSameValue( actual, expected, 150.0 ), true, 'within tolerance. x: ' + x + '. w: ' + w + '. Value: ' + actual + '. Expected: ' + expected + '.' );


A bit high value for ULP Diff here. Consider a relative-error tolerance (as other incr/* tests use) or fixtures bounded away from zero.

Arjan-P · 2026-07-22T13:34:40Z

My bad, will be more mindful going forth. I think the package is also missing a README.md. Thank you for the feedback, will address these as soon as possible.

Arjan-P added 7 commits July 22, 2026 13:51

Arjan-P requested a review from a team July 22, 2026 08:24

stdlib-bot added Statistics Issue or pull request related to statistical functionality. Needs Review A pull request which needs code review. labels Jul 22, 2026

Arjan-P changed the title ~~feat; Add stats/incr/nanwmean~~ feat: Add stats/incr/nanwmean Jul 22, 2026

Neerajpathak07 changed the title ~~feat: Add stats/incr/nanwmean~~ feat: add stats/incr/nanwmean Jul 22, 2026

stdlib-bot added the bot: In Progress Pull request is currently awaiting automation. label Jul 22, 2026

chore: update copyright years

bdece4f

stdlib-bot removed the bot: In Progress Pull request is currently awaiting automation. label Jul 22, 2026

Neerajpathak07 requested changes Jul 22, 2026

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Neerajpathak07 added Needs Changes Pull request which needs changes before being merged. and removed Needs Review A pull request which needs code review. labels Jul 22, 2026

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