dask/dask

Add static type annotations

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#11,047 opened on Apr 11, 2024

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good first issue

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Description

I am having trouble with using Dask in a project that uses PyRight because Dask does not use static type annotations/

Take, da.from_array, for example: https://github.com/dask/dask/blob/b2ec1e1a2361db1e269ba86c7c59d3f6df70a02d/dask/array/core.py#L3307-L3317

Or array.rechunk: https://github.com/dask/dask/blob/b2ec1e1a2361db1e269ba86c7c59d3f6df70a02d/dask/array/rechunk.py#L268-L275

PyRight complains if you use anything but a str for chunks:

image

Argument of type "tuple[Literal[1], Literal[-1], Literal[-1]]" cannot be assigned to parameter "chunks" of type "str" in function "from_array"
  "tuple[Literal[1], Literal[-1], Literal[-1]]" is incompatible with "str"

This happens because in from_array and rechunk, chunks="auto" infers to a str type.

Is there an awareness of this problem? Is there a known solution? If not, is there a plan to fix this?

Contributor guide

Research direction
Look at the existing type annotations in the Dask codebase for similar functions and add proper type hints using Python's typing module (e.g., Union, Tuple, Literal) to the 'chunks' parameter in 'from array' and 'rechunk' functions.
Tech stack
python
Domain
data
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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Active
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Clear
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PythonGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70