    mouse     1      3
        rabbit    4      6

        >>> # select columns by regular expression
        >>> df.filter(regex='e$', axis=1)
                 one  three
        mouse     1      3
        rabbit    4      6

        >>> # select rows containing 'bbi'
        >>> df.filter(like='bbi', axis=0)
                 one  two  three
        rabbit    4    5      6
        r