Doc: Adds example of joining a series to a dataframe. #19235
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pdpark
commented
Jan 14, 2018
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pdpark
commented
- closes: Equivalent of Series.map for DataFrame #12550
| # The series has a multi-index with levels corresponding to columns in the DataFrame we want to merge with | ||
| ser = pd.Series( | ||
| ['a', 'b', 'c', 'd', 'e', 'f'], | ||
| index=pd.MultiIndex.from_arrays([["A", "B", "C"]*2, [1, 2, 3, 4, 5, 6]]) |
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Use the names parameter here, instead of setting it below.
| ser.index.names=['Let','Num'] | ||
| ser | ||
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| # reset_index turns the multi-level row index into columns, which requires a DataFrame |
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I think this can be removed, to make the example shorter. I'd just write it as
# Convert the Series to a DataFrame and merge
pd.merge(df, ser.reset_index(), on=['Let', 'Num'])| @@ -714,6 +714,31 @@ either the left or right tables, the values in the joined table will be | |||
| labels=['left', 'right'], vertical=False); | |||
| plt.close('all'); | |||
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| To join a Series and a DataFrame, the Series has to be transformed into a DataFrame first: | |||
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Explain that the Series is a MultiIndexed series, and that's what you're joining on. Something like
To join a Series with a MultiIndex and a DataFrame, using the levels of the
MultiIndex and columns from the DataFrame, transform the Series to a DataFrame
using :meth:`Series.reset_index`.
| type(df2) | ||
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| # Now we merge the DataFrames | ||
| pd.merge(df, df2, on=['Let','Num']) |
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Space after the comma.
| ser | ||
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| # Name the row index levels | ||
| ser.index.names=['Let','Num'] |
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Space after the comma.
| # The series has a multi-index with levels corresponding to columns in the DataFrame we want to merge with | ||
| ser = pd.Series( | ||
| ['a', 'b', 'c', 'd', 'e', 'f'], | ||
| index=pd.MultiIndex.from_arrays([["A", "B", "C"]*2, [1, 2, 3, 4, 5, 6]]) |
Codecov Report
@@ Coverage Diff @@
## master #19235 +/- ##
==========================================
- Coverage 91.82% 91.55% -0.28%
==========================================
Files 152 147 -5
Lines 49248 48797 -451
==========================================
- Hits 45222 44675 -547
- Misses 4026 4122 +96
Continue to review full report at Codecov.
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can you rebase and update |
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Will do - have been absent due to starting new job, but plan to spend some time on this. |
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Closing as stale. |
