Source code for torch_geometric.utils._degree

from typing import Optional

import torch
from torch import Tensor

from torch_geometric.utils.num_nodes import maybe_num_nodes

[docs]def degree(index: Tensor, num_nodes: Optional[int] = None, dtype: Optional[torch.dtype] = None) -> Tensor: r"""Computes the (unweighted) degree of a given one-dimensional index tensor. Args: index (LongTensor): Index tensor. num_nodes (int, optional): The number of nodes, *i.e.* :obj:`max_val + 1` of :attr:`index`. (default: :obj:`None`) dtype (:obj:`torch.dtype`, optional): The desired data type of the returned tensor. :rtype: :class:`Tensor` Example: >>> row = torch.tensor([0, 1, 0, 2, 0]) >>> degree(row, dtype=torch.long) tensor([3, 1, 1]) """ N = maybe_num_nodes(index, num_nodes) out = torch.zeros((N, ), dtype=dtype, device=index.device) one = torch.ones((index.size(0), ), dtype=out.dtype, device=out.device) return out.scatter_add_(0, index, one)