internals.py 文件源码

def shift(self, periods, axis=0, mgr=None):
        """ shift the block by periods """
        N = len(self.values.T)
        indexer = np.zeros(N, dtype=int)
        if periods > 0:
            indexer[periods:] = np.arange(N - periods)
        else:
            indexer[:periods] = np.arange(-periods, N)
        new_values = self.values.to_dense().take(indexer)
        # convert integer to float if necessary. need to do a lot more than
        # that, handle boolean etc also
        new_values, fill_value = com._maybe_upcast(new_values)
        if periods > 0:
            new_values[:periods] = fill_value
        else:
            new_values[periods:] = fill_value
        return [self.make_block_same_class(new_values,
                                           placement=self.mgr_locs)]