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Friday, November 10, 2017

Pandas Data frame update update


Pandas data frame update should be one of the most useful functions.





DataFrame.update(otherjoin='left'overwrite=Truefilter_func=Noneraise_conflict=False)[source]
Modify DataFrame in place using non-NA values from passed DataFrame. Aligns on indices


https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.update.html

Pandas dataframe merge with update data

Pandas dataframe merge with update data
print (pd.concat([df1, df2]).drop_duplicates('date', keep='last'))
date value
0 2017-01-01 1
1 2017-01-02 1
2 2017-01-03 1
0 2017-01-04 2
1 2017-01-05 2
2 2017-01-06 2
3 2017-01-07 2
4 2017-01-08 2
You can use concat with drop_duplicates by column date and keep last values:
Concat works, but drop_dublicates('ID', keep='last') does not.

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