Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/networkx/generators/triads.py

@@ -0,0 +1,75 @@
+# See https://github.com/networkx/networkx/pull/1474
+# Copyright 2011 Reya Group <http://www.reyagroup.com>
+# Copyright 2011 Alex Levenson <alex@isnotinvain.com>
+# Copyright 2011 Diederik van Liere <diederik.vanliere@rotman.utoronto.ca>
+"""Functions that generate the triad graphs, that is, the possible
+digraphs on three nodes.
+
+"""
+from networkx.classes import DiGraph
+
+__all__ = ["triad_graph"]
+
+#: Dictionary mapping triad name to list of directed edges in the
+#: digraph representation of that triad (with nodes 'a', 'b', and 'c').
+TRIAD_EDGES = {
+    "003": [],
+    "012": ["ab"],
+    "102": ["ab", "ba"],
+    "021D": ["ba", "bc"],
+    "021U": ["ab", "cb"],
+    "021C": ["ab", "bc"],
+    "111D": ["ac", "ca", "bc"],
+    "111U": ["ac", "ca", "cb"],
+    "030T": ["ab", "cb", "ac"],
+    "030C": ["ba", "cb", "ac"],
+    "201": ["ab", "ba", "ac", "ca"],
+    "120D": ["bc", "ba", "ac", "ca"],
+    "120U": ["ab", "cb", "ac", "ca"],
+    "120C": ["ab", "bc", "ac", "ca"],
+    "210": ["ab", "bc", "cb", "ac", "ca"],
+    "300": ["ab", "ba", "bc", "cb", "ac", "ca"],
+}
+
+
+def triad_graph(triad_name):
+    """Returns the triad graph with the given name.
+
+    Each string in the following tuple is a valid triad name::
+
+        ('003', '012', '102', '021D', '021U', '021C', '111D', '111U',
+         '030T', '030C', '201', '120D', '120U', '120C', '210', '300')
+
+    Each triad name corresponds to one of the possible valid digraph on
+    three nodes.
+
+    Parameters
+    ----------
+    triad_name : string
+        The name of a triad, as described above.
+
+    Returns
+    -------
+    :class:`~networkx.DiGraph`
+        The digraph on three nodes with the given name. The nodes of the
+        graph are the single-character strings 'a', 'b', and 'c'.
+
+    Raises
+    ------
+    ValueError
+        If `triad_name` is not the name of a triad.
+
+    See also
+    --------
+    triadic_census
+
+    """
+    if triad_name not in TRIAD_EDGES:
+        raise ValueError(
+            f'unknown triad name "{triad_name}"; use one of the triad names'
+            " in the TRIAD_NAMES constant"
+        )
+    G = DiGraph()
+    G.add_nodes_from("abc")
+    G.add_edges_from(TRIAD_EDGES[triad_name])
+    return G