chore: import upstream snapshot with attribution

2026-07-13 13:35:51 +08:00
commit c36a561cd8
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+"""KarateClub Dataset
+"""
+import networkx as nx
+import numpy as np
+
+from .. import backend as F
+from ..convert import from_networkx
+from .dgl_dataset import DGLDataset
+from .utils import deprecate_property
+
+__all__ = ["KarateClubDataset", "KarateClub"]
+
+
+class KarateClubDataset(DGLDataset):
+    r"""Karate Club dataset for Node Classification
+
+    Zachary's karate club is a social network of a university
+    karate club, described in the paper "An Information Flow
+    Model for Conflict and Fission in Small Groups" by Wayne W. Zachary.
+    The network became a popular example of community structure in
+    networks after its use by Michelle Girvan and Mark Newman in 2002.
+    Official website: `<http://konect.cc/networks/ucidata-zachary/>`_
+
+    Karate Club dataset statistics:
+
+    - Nodes: 34
+    - Edges: 156
+    - Number of Classes: 2
+
+    Parameters
+    ----------
+    transform : callable, optional
+        A transform that takes in a :class:`~dgl.DGLGraph` object and returns
+        a transformed version. The :class:`~dgl.DGLGraph` object will be
+        transformed before every access.
+
+    Attributes
+    ----------
+    num_classes : int
+        Number of node classes
+
+    Examples
+    --------
+    >>> dataset = KarateClubDataset()
+    >>> num_classes = dataset.num_classes
+    >>> g = dataset[0]
+    >>> labels = g.ndata['label']
+    """
+
+    def __init__(self, transform=None):
+        super(KarateClubDataset, self).__init__(
+            name="karate_club", transform=transform
+        )
+
+    def process(self):
+        kc_graph = nx.karate_club_graph()
+        label = np.asarray(
+            [kc_graph.nodes[i]["club"] != "Mr. Hi" for i in kc_graph.nodes]
+        ).astype(np.int64)
+        label = F.tensor(label)
+        g = from_networkx(kc_graph)
+        g.ndata["label"] = label
+        self._graph = g
+        self._data = [g]
+
+    @property
+    def num_classes(self):
+        """Number of classes."""
+        return 2
+
+    def __getitem__(self, idx):
+        r"""Get graph object
+
+        Parameters
+        ----------
+        idx : int
+            Item index, KarateClubDataset has only one graph object
+
+        Returns
+        -------
+        :class:`dgl.DGLGraph`
+
+            graph structure and labels.
+
+            - ``ndata['label']``: ground truth labels
+        """
+        assert idx == 0, "This dataset has only one graph"
+        if self._transform is None:
+            return self._graph
+        else:
+            return self._transform(self._graph)
+
+    def __len__(self):
+        r"""The number of graphs in the dataset."""
+        return 1
+
+
+KarateClub = KarateClubDataset