Convert to pandas DataFrame.

        Note the data is expected to be evaluated.

        Returns
        -------
        pandas.frame.DataFrame

def to_pandas(self):
        """Convert to pandas DataFrame.

        Note the data is expected to be evaluated.

        Returns
        -------
        pandas.frame.DataFrame

        """
        from pandas import DataFrame as PandasDataFrame

        pandas_index = self.index.to_pandas()
        pandas_data = OrderedDict((column.name, column.to_pandas())
                                  for column in self._iter())

        return PandasDataFrame(pandas_data, pandas_index)