pydata / pydata/xarray

apply_ufunc should include variable names in error messages

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#2,078 4 comments 1 reaction 0 assignees View on GitHub

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contrib-good-first-issue topic-error reporting
Dominant language
Python
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Description

This would make it easier to debug issues with dimensions.

For example, in this example from StackOverflow, the error message was ValueError: operand to apply_ufunc has required core dimensions ['time', 'lat', 'lon'], but some of these are missing on the input variable: ['lat', 'lon'].

A better error message would be: ValueError: operand to apply_ufunc has required core dimensions ['time', 'lat', 'lon'], but some of these are missing on input variable 'status': ['lat', 'lon']

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating the apply_ufunc implementation and its existing error handling or tests. Update the missing-core-dimensions error so it identifies the input variable, matching the message format shown in the issue, and verify the example failure reports the variable name.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
data
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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