[SPARK-23018][PYTHON] Fix createDataFrame from Pandas timestamp series assignment #20213
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repro to get the warning (this is the non-Arrow code path) import numpy as np
import pandas as pd
pdf = pd.DataFrame(np.random.rand(100, 2))
df = spark.createDataFrame(pdf[:10])
'''
/home/bryan/git/spark/python/pyspark/sql/session.py:476: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
pdf[column] = s
''' |
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ping @ueshin @HyukjinKwon , I'm not too sure if this could cause any real problems, but the warning is a little unsettling and can be avoided. This change will only assign series back to the pdf if was a modified timestamp column, and the rest are just copied if needed. |
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Test build #85890 has finished for PR 20213 at commit
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LGTM. |
HyukjinKwon
approved these changes
Jan 10, 2018
| copied = True | ||
| pdf[field.name] = s | ||
| if s is not pdf[field.name]: | ||
| if not copied: |
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BTW, what's diff between:
if s is not pdf[field.name]:
if not copied:
vs
if not copied and s is not pdf[field.name]:
?
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Looks like it was separated for assigning pdf[field.name] = s only if s is not pdf[field.name].
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Ah, sure. Makes sense. I rushed to read.
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Thanks! merging to master/2.3. |
asfgit
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Jan 10, 2018
…s assignment ## What changes were proposed in this pull request? This fixes createDataFrame from Pandas to only assign modified timestamp series back to a copied version of the Pandas DataFrame. Previously, if the Pandas DataFrame was only a reference (e.g. a slice of another) each series will still get assigned back to the reference even if it is not a modified timestamp column. This caused the following warning "SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame." ## How was this patch tested? existing tests Author: Bryan Cutler <cutlerb@gmail.com> Closes #20213 from BryanCutler/pyspark-createDataFrame-copy-slice-warn-SPARK-23018. (cherry picked from commit 7bcc266) Signed-off-by: Takuya UESHIN <ueshin@databricks.com>
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Thanks @ueshin and @HyukjinKwon ! |
BryanCutler
deleted the
pyspark-createDataFrame-copy-slice-warn-SPARK-23018
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What changes were proposed in this pull request?
This fixes createDataFrame from Pandas to only assign modified timestamp series back to a copied version of the Pandas DataFrame. Previously, if the Pandas DataFrame was only a reference (e.g. a slice of another) each series will still get assigned back to the reference even if it is not a modified timestamp column. This caused the following warning "SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame."
How was this patch tested?
existing tests