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FIX-#5112: allows empty partition to be passed into query_compiler.dt_prop_map #5133

Merged
merged 8 commits into from
Oct 27, 2022
Merged

FIX-#5112: allows empty partition to be passed into query_compiler.dt_prop_map #5133

merged 8 commits into from
Oct 27, 2022

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billiam-wang
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@billiam-wang billiam-wang commented Oct 18, 2022 •
edited by mvashishtha
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Signed-off-by: Bill Wang billiam@ponder.io

What do these changes do?

Adds special case when empty partition is passed into dt_prop_map function. Previously, calling squeeze on a DataFrame partition with no columns would return the same DataFrame and then attempt to access a Series property. After the fix, a DataFrame partition with no columns simply returns an empty DataFrame.

  • first commit message and PR title follow format outlined here

    NOTE: If you edit the PR title to match this format, you need to add another commit (even if it's empty) or amend your last commit for the CI job that checks the PR title to pick up the new PR title.

  • passes flake8 modin/ asv_bench/benchmarks scripts/doc_checker.py
  • passes black --check modin/ asv_bench/benchmarks scripts/doc_checker.py
  • signed commit with git commit -s
  • Resolves BUG: (v0.16.0) Series object being treated as a data frame object when using dt accessor #5112
  • tests added and passing
  • module layout described at docs/development/architecture.rst is up-to-date

@billiam-wang billiam-wang requested a review from a team as a code owner October 18, 2022 09:39
pyrito
pyrito reviewed Oct 18, 2022
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modin/core/storage_formats/pandas/query_compiler.py
@@ -147,7 +147,10 @@ def _dt_prop_map(property_name):

def dt_op_builder(df, *args, **kwargs):
"""Access specified date-time property of the passed frame."""
prop_val = getattr(df.squeeze(axis=1).dt, property_name)
squeezed_df = df.squeeze(axis=1)
if isinstance(squeezed_df, pandas.DataFrame) and len(squeezed_df.columns) == 0:
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is it ever possible for squeezed_df to ever be an empty Series?

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squeezed_df can become an empty Series if df is originally a DataFrame with a single column but no rows.

If squeezed_df becomes an empty Series, there are 2 possible outcomes. If the Series dtype is datetime64[ns], it should return an empty DataFrame as expected. If the Series dtype is anything else, it will error because dt is only accessible to datetimelike values.

Is there a situation where the passed in df would be a DataFrame with a single column but no rows and the dtype is not datetime64[ns] when it is supposed to be?

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I can't think of such a case.

@billiam-wang
FIX-modin-project#5112: allows empty partition to be passed into quer…
ccbc11e 
…y_compiler.dt_prop_map

Signed-off-by: Bill Wang <billiam@ponder.io>
@billiam-wang
Added comments to tests and assert to access dt on Series
3a82372 
Signed-off-by: Bill Wang <billiam@ponder.io>
@billiam-wang
Small changes to fix flake8 tests
892e2dc 
Signed-off-by: Bill Wang <billiam@ponder.io>
@billiam-wang
Corrected test_dt assert statement
83678ee 
Signed-off-by: Bill Wang <billiam@ponder.io>
@billiam-wang
Corrected tests for BaseOnPython execution
99f1cd9 
Signed-off-by: Bill Wang <billiam@ponder.io>
@billiam-wang
Removed print statements from test/util.py
cde899c 
Signed-off-by: Bill Wang <billiam@ponder.io>
mvashishtha
mvashishtha reviewed Oct 25, 2022
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I have some minor comments.

modin/pandas/test/test_series.py Outdated Show resolved Hide resolved
modin/pandas/test/test_series.py Outdated Show resolved Hide resolved
modin/core/storage_formats/pandas/query_compiler.py Outdated Show resolved Hide resolved
pyrito
pyrito approved these changes Oct 26, 2022
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LGTM

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pyrito commented Oct 26, 2022

Might need to re-run CI here @Billy2551 . Just commit an empty commit to re-trigger the runs.

@mvashishtha mvashishtha merged commit f492ba9 into modin-project:master Oct 27, 2022
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@pyrito pyrito pyrito approved these changes

@mvashishtha mvashishtha mvashishtha approved these changes

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BUG: (v0.16.0) Series object being treated as a data frame object when using dt accessor
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@billiam-wang @pyrito @mvashishtha