Index.
fillna
Fill NA/NaN values with the specified value.
Scalar value to use to fill holes (e.g. 0). This value cannot be a list-likes.
A dict of item->dtype of what to downcast if possible, or the string ‘infer’ which will try to downcast to an appropriate equal type (e.g. float64 to int64 if possible).
See also
DataFrame.fillna
Fill NaN values of a DataFrame.
Series.fillna
Fill NaN Values of a Series.