chore: import upstream snapshot with attribution

easygraph/functions/hypergraph/null_model/hypergraph_classic.py

@@ -0,0 +1,39 @@
+import itertools
+
+import easygraph as eg
+
+from easygraph.utils.exception import EasyGraphError
+
+
+__all__ = ["empty_hypergraph", "complete_hypergraph"]
+
+
+def empty_hypergraph(N=1):
+    """
+
+    Parameters
+    ----------
+    N number of node in Hypergraph, default 1
+
+    Returns
+    -------
+    A eg.Hypergraph with n_num node, without any hyperedge.
+
+    """
+    return eg.Hypergraph(N)
+
+
+def complete_hypergraph(n, include_singleton=False):
+    if n == 0:
+        raise EasyGraphError("The number of nodes in a Hypergraph can not be zero")
+    # init
+    # print("easygraph:",eg)
+    hypergraph = eg.Hypergraph(n)
+    total_hyperedegs = []
+    if n > 1:
+        start = 1 if include_singleton else 2
+        for size in range(start, n + 1):
+            hyperedges = itertools.combinations(list(range(n)), size)
+            total_hyperedegs.extend(list(hyperedges))
+        hypergraph.add_hyperedges(total_hyperedegs)
+    return hypergraph