pandas.DataFrame.combine_first — pandas 1.0.5 documentation (original) (raw)
DataFrame. combine_first(self, other: ‘DataFrame’) → ’DataFrame’[source]¶
Update null elements with value in the same location in other.
Combine two DataFrame objects by filling null values in one DataFrame with non-null values from other DataFrame. The row and column indexes of the resulting DataFrame will be the union of the two.
Parameters
otherDataFrame
Provided DataFrame to use to fill null values.
Returns
DataFrame
See also
Perform series-wise operation on two DataFrames using a given function.
Examples
df1 = pd.DataFrame({'A': [None, 0], 'B': [None, 4]}) df2 = pd.DataFrame({'A': [1, 1], 'B': [3, 3]}) df1.combine_first(df2) A B 0 1.0 3.0 1 0.0 4.0
Null values still persist if the location of that null value does not exist in other
df1 = pd.DataFrame({'A': [None, 0], 'B': [4, None]}) df2 = pd.DataFrame({'B': [3, 3], 'C': [1, 1]}, index=[1, 2]) df1.combine_first(df2) A B C 0 NaN 4.0 NaN 1 0.0 3.0 1.0 2 NaN 3.0 1.0