def find_all(self, pattern):
        """
        Return the subset of this RcParams dictionary whose keys match,
        using :func:`re.search`, the given ``pattern``.

        Parameters
        ----------
        pattern: str
            pattern as suitable for re.compile

        Returns
        -------
        RcParams
            RcParams instance with entries that match the given `pattern`

        Notes
        -----
        Changes to the returned dictionary are (different from
        :meth:`find_and_replace` are *not* propagated to the parent RcParams
        dictionary.

        See Also
        --------
        find_and_replace"""
        pattern_re = re.compile(pattern)
        ret = RcParams()
        ret.defaultParams = self.defaultParams
        ret.update((key, value) for key, value in self.items()
                   if pattern_re.search(key))
        return ret