patch: group by n_unique
#917
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
FBruzzesi
commented
Sep 6, 2024
narwhals/_arrow/group_by.py
Outdated
Comment on lines
20
to
21
| "std": "stddev", | ||
| "var": "variance", |
There was a problem hiding this comment.
Found these other two cases while reading pyarrow grouped table aggregations (https://arrow.apache.org/docs/python/compute.html#py-grouped-aggrs)
FBruzzesi
commented
Sep 6, 2024
narwhals/_dask/group_by.py
Outdated
Comment on lines
20
to
28
| def n_unique() -> dd.Aggregation: | ||
| import dask.dataframe as dd # ignore-banned-import | ||
|
|
||
| return dd.Aggregation( | ||
| name="nunique", | ||
| chunk=lambda s: s.apply(lambda x: list(set(x))), | ||
| agg=lambda s0: s0.obj.groupby(level=list(range(s0.obj.index.nlevels))).sum(), | ||
| finalize=lambda s1: s1.apply(lambda final: len(set(final))), | ||
| ) |
There was a problem hiding this comment.
This comes from the dask documentation itself.
For some reason, nunique kw only works in
df_dd.groupby("a").b.nunique()but not in agg context
There was a problem hiding this comment.
thanks for digging this up in the dask docs!
I think this is way more complex than it needs to be - i've pushed something much simpler which seems to work
10 tasks
MarcoGorelli
approved these changes
Sep 6, 2024
There was a problem hiding this comment.
thanks @FBruzzesi !
the main issue missing was the handling of null values, but i've added some commits to take care of that
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
What type of PR is this? (check all applicable)
Related issues
groupby-aggraises #915Checklist
If you have comments or can explain your changes, please do so below.
Attempt for #915, comments in the code