def dframe(self):
        """
        Deprecated method to convert a MultiDimensionalMapping to
        a pandas DataFrame. Conversion to a dataframe now only
        supported by specific subclasses such as UniformNdMapping
        types.
        """
        self.param.warning("The MultiDimensionalMapping.dframe method is "
                           "deprecated and should no longer be used. "
                           "Use a more specific subclass which does support "
                           "the dframe method instead, e.g. a HoloMap.")
        try:
            import pandas
        except ImportError:
            raise Exception("Cannot build a DataFrame without the pandas library.")
        labels = self.dimensions('key', True) + [self.group]
        return pandas.DataFrame(
            [dict(zip(labels, k + (v,))) for (k, v) in self.data.items()])