Fill NA/NaN values with value.
Value to use to fill holes (e.g. 0), alternately a dict/Series/DataFrame of values specifying which value to use for each index (for a Series) or column (for a DataFrame). Values not in the dict/Series/DataFrame will not be filled. This value cannot be a list.
Axis along which to fill missing values. For Series this parameter is unused and defaults to 0.
If True, fill in-place. Note: this will modify any other views on this object (e.g., a no-copy slice for a column in a DataFrame).
This is the maximum number of entries along the entire axis where NaNs will be filled. Must be greater than 0 if not None.
Object with missing values filled or None if inplace=True
.
See also
ffill
Fill values by propagating the last valid observation to next valid.
bfill
Fill values by using the next valid observation to fill the gap.
interpolate
Fill NaN values using interpolation.
reindex
Conform object to new index.
asfreq
Convert TimeSeries to specified frequency.
Notes
For non-object dtype, value=None
will use the NA value of the dtype. See more details in the Filling missing data section.
Examples
>>> df = pd.DataFrame( ... [ ... [np.nan, 2, np.nan, 0], ... [3, 4, np.nan, 1], ... [np.nan, np.nan, np.nan, np.nan], ... [np.nan, 3, np.nan, 4], ... ], ... columns=list("ABCD"), ... ) >>> df A B C D 0 NaN 2.0 NaN 0.0 1 3.0 4.0 NaN 1.0 2 NaN NaN NaN NaN 3 NaN 3.0 NaN 4.0
Replace all NaN elements with 0s.
>>> df.fillna(0) A B C D 0 0.0 2.0 0.0 0.0 1 3.0 4.0 0.0 1.0 2 0.0 0.0 0.0 0.0 3 0.0 3.0 0.0 4.0
Replace all NaN elements in column âAâ, âBâ, âCâ, and âDâ, with 0, 1, 2, and 3 respectively.
>>> values = {"A": 0, "B": 1, "C": 2, "D": 3} >>> df.fillna(value=values) A B C D 0 0.0 2.0 2.0 0.0 1 3.0 4.0 2.0 1.0 2 0.0 1.0 2.0 3.0 3 0.0 3.0 2.0 4.0
Only replace the first NaN element.
>>> df.fillna(value=values, limit=1) A B C D 0 0.0 2.0 2.0 0.0 1 3.0 4.0 NaN 1.0 2 NaN 1.0 NaN 3.0 3 NaN 3.0 NaN 4.0
When filling using a DataFrame, replacement happens along the same column names and same indices
>>> df2 = pd.DataFrame(np.zeros((4, 4)), columns=list("ABCE")) >>> df.fillna(df2) A B C D 0 0.0 2.0 0.0 0.0 1 3.0 4.0 0.0 1.0 2 0.0 0.0 0.0 NaN 3 0.0 3.0 0.0 4.0
Note that column D is not affected since it is not present in df2.
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