[RFC]: achieve ndarray API parity with built-in JavaScript arrays

[kgryte]

Description

This RFC proposes achieving ndarray API parity with built-in JavaScript arrays. Built-in JavaScript Array and TypedArray objects have a number of methods for searching, manipulating, sorting, and transforming array data.

The goal of this RFC is to add functional APIs providing equivalent functionality for ndarrays. By providing these APIs, stdlib can offer a powerful toolset using a similar vocabulary and interface design as existing art for working with ndarrays. This should help reduce the barrier to ndarray adoption and encourage their more widespread use.

Note, however, that ndarrays have considerable additional complexity due to their multi-dimensional nature, and, in particular, element-wise iteration requires specialized kernels for handling non-contiguous underlying data.

There does exist precedent in stdlib for such kernels (e.g., ndarray/base/assign, ndarray/base/nullary, and ndarray/base/unary). Those packages also provide C APIs which may or may not be relevant to the functional APIs proposed in this RFC.

What follows is an initial list of Array.prototype.* methods and notes regarding whether an equivalent already exists or what constraints we need to consider when designing ndarray equivalent packages.

Top-level: ndarray/*

• Array.prototype.at

  • ndarray/at

• Array.prototype.entries

  • ndarray/iter/entries

• Array.prototype.every

  • ndarray/every

• Array.prototype.forEach

  • ndarray/for-each

• Array.prototype.map

  • ndarray/map

• Array.prototype.filter

  • ndarray/filter

• Array.prototype.slice

  • ndarray/slice

• Array.prototype.keys

  • ndarray/iter/indices

• Array.prototype.values

  • ndarray/iter/values

• Array.prototype.includes

  • ndarray/includes

• Array.prototype.indexOf

  • blas/ext/index-of

• Array.prototype.find

  • ndarray/base/find
  • ndarray/find

• Array.prototype.findIndex

  • blas/ext/find-index

• Array.prototype.lastIndexOf

  • blas/ext/last-index-of

• Array.prototype.some

  • ndarray/any

• Array.prototype.findLast

  • ndarray/find-last

• Array.prototype.findLastIndex

  • blas/ext/find-last-index

• Array.prototype.reverse

  • ndarray/reverse

• Array.prototype.toReversed

  • ndarray/base/to-reversed
  • ndarray/reversed

• Array.prototype.sort

  • multiple functions for different sorting algorithms.
  • blas/ext/sorthp.

• Array.prototype.toSorted

  • multiple functions for different sorting algorithms.
  • blas/ext/to-sortedhp

• Array.prototype.fill

  • ndarray/fill and ndarray/fill-by
  • ndarray/fill-slice

• Array.prototype.flat

  • ndarray/flatten

• Array.prototype.reduce

  • reduction; specify one or more axes

• Array.prototype.concat

  • ndarray/concat

• Array.prototype.copyWithin (WIP)

  • specify axis
  • how would this work for strided arrays?
  • for ideal case, would prefer delegating to array prototype method, as likely faster; for non-ideal case, would need to take special care to avoid overwriting accessed values.
  • Slice + assign?
  • Temporary buffer for when there is overlap.

• Array.prototype.reduceRight

  • reduction; specify one or more axes
  • iterate in reverse direction

• Array.prototype.flatMap

  • ndarray/flatten-by

• Array.prototype.join

  • blas/ext/join

• Array.prototype.pop

  • ndarray/pop

• Array.prototype.push

  • ndarray/concat1d

• Array.prototype.shift

  • ndarray/shift

• Array.prototype.splice (WIP)

  • needs R&D
  • would involving slicing, concatenation, and data copy

• Array.prototype.toLocaleString (WIP)

  • needs R&D

• Array.prototype.toSpliced (WIP)

  • needs R&D

• Array.prototype.toString (WIP)

  • just call ndarray.toString()?

• Array.prototype.unshift

  • ndarray/unshift

• Array.prototype.with

  • ndarray/with

Base: ndarray/base/*

• Array.prototype.fill

  • ndarray/base/fill

• Array.prototype.forEach

  • ndarray/base/for-each

• Array.prototype.map

  • ndarray/base/map

• Array.prototype.reverse

  • ndarray/base/reverse

• Array.prototype.slice

  • ndarray/base/slice

• Array.prototype.toReversed

  • ndarray/base/to-reversed

• Array.prototype.every

  • ndarray/base/every-by

• Array.prototype.some

  • ndarray/base/any

• Array.prototype.find

  • ndarray/base/find

• Array.prototype.pop

  • ndarray/base/pop

• Array.prototype.shift

  • ndarray/base/shift

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Checklist

• I have read and understood the Code of Conduct.
• Searched for existing issues and pull requests.
• The issue name begins with RFC:.

[kgryte]

cc @headlessNode

[SarthakPaandey]

I want to work on this issue @kgryte and could you elaborate on the specific goals of aligning ndarray APIs with JavaScript arrays? How will this benefit users and developers?

[kgryte]

How will this benefit users and developers?

This is already addressed in the OP. Second paragraph.

[SarthakPaandey]

Yup! Starting work on this!

[kgryte]

@SarthakPaandey Before you begin, it would be best to communicate what you're planning to work on. Some of the above routines are easier than others and should be addressed first. Reductions require R&D and should only be worked on once we've determined the best approach.

[SarthakPaandey]

"Understood, @kgryte. I'll prioritize the routines that are comparatively easier and communicate my plan before starting. I'll defer work on reductions until we've established the best approach. Thanks for the guidance!

[headlessNode]

@kgryte I have started to work on the map method. I plan to submit PR for it when I've implemented the kernels for it up to 3d. This way, it would be possible to get feedback from you earlier and it would be easier for me to work on the feedback. Does that seem reasonable?

[kgryte]

@headlessNode That makes sense. I am currently working on for-each, which is related.