history_container.py 文件源码

def _add_field(self, field):
        """
        Adds a new field to the container.
        """
        # self.fields is already sorted, so we just need to insert the new
        # field in the correct index.
        ls = list(self.fields)
        insort_left(ls, field)
        self.fields = pd.Index(ls)
        # unset fillable fields cache
        self._ffillable_fields = None

        self._realign_fields()
        self.last_known_prior_values = self.last_known_prior_values.reindex(
            index=self.prior_values_index,
        )
        return field