def collect_active_part(beamed_tensor, curr_active_inst_idx,
                                n_prev_active_inst, n_bm):
            ''' Collect tensor parts associated to active instances. '''

            beamed_tensor_shape = beamed_tensor.shape
            n_curr_active_inst = len(curr_active_inst_idx)
            new_shape = (n_curr_active_inst * n_bm, beamed_tensor_shape[1],
                         beamed_tensor_shape[2])

            beamed_tensor = beamed_tensor.reshape([n_prev_active_inst, -1])
            beamed_tensor = beamed_tensor.index_select(
                curr_active_inst_idx, axis=0)
            beamed_tensor = beamed_tensor.reshape(new_shape)

            return beamed_tensor
 Collect tensor parts associated to active instances. 
pytorchocr/modeling/heads/rec_nrtr_head.py