dgl.DGLGraph.num_nodes¶

DGLGraph.num_nodes(ntype=None)[source]¶

Return the number of nodes in the graph.

Parameters: ntype (str, optional) – The node type name. If given, it returns the number of nodes of the type. If not given (default), it returns the total number of nodes of all types.
Returns: The number of nodes.
Return type: int

Examples

The following example uses PyTorch backend.

>>> import dgl
>>> import torch

Create a graph with two node types – ‘user’ and ‘game’.

>>> g = dgl.heterograph({
...     ('user', 'follows', 'user'): (torch.tensor([0, 1]), torch.tensor([1, 2])),
...     ('user', 'plays', 'game'): (torch.tensor([3, 4]), torch.tensor([5, 6]))
... })

Query for the number of nodes.

>>> g.num_nodes('user')
5
>>> g.num_nodes('game')
7
>>> g.num_nodes()
12