pandas.Series.isnull — pandas 1.3.5 documentation
pandas.pydata.org › api › pandaspandas.Series.isnull. ¶. Detect missing values. Return a boolean same-sized object indicating if the values are NA. NA values, such as None or numpy.NaN, gets mapped to True values. Everything else gets mapped to False values. Characters such as empty strings '' or numpy.inf are not considered NA values (unless you set pandas.options.mode.use ...
pandas.Series.str.zfill — pandas 1.3.5 documentation
pandas.pydata.org › pandasSeries.str.zfill(width) [source] ¶. Pad strings in the Series/Index by prepending ‘0’ characters. Strings in the Series/Index are padded with ‘0’ characters on the left of the string to reach a total string length width. Strings in the Series/Index with length greater or equal to width are unchanged. Parameters.