def apply_units_to_cache(self, data):
        """
        Apply units to cached data read using :class:`JSONReader`.

        :param data: Cached data.
        :type data: dict
        :return: data with units
        """
        # iterate through sheets in parameters
        # iterate through the parameters on each sheet
        for param, pval in self.parameters.iteritems():
            # try to apply units
            try:
                data[param] *= UREG(str(pval.get('units') or ''))
            except TypeError:
                continue
        return data