start GraphData

Author: rocky

pymathics/graph/__main__.py

@@ -41,11 +41,19 @@
     # And many others. Is there a list somewhere?
 }
 
+WL_LAYOUT_TO_MATPLOTLIB = {
+    "CircularEmbedding": "circular",
+    "SpiralEmbedding": "spiral",
+    "SpectralEmbedding": "spectral",
+    "SpringEmbedding": "spring",
+    # And many others. Is there a list somewhere?
+}
+
 DEFAULT_GRAPH_OPTIONS = {
     "DirectedEdges": "False",
     "EdgeStyle": "{}",
     "EdgeWeight": "{}",
-    "GraphLayout": "{}",
+    "GraphLayout": "Null",
     "PlotLabel": "Null",
     "VertexLabels": "False",
     "VertexSize": "{}",
@@ -59,6 +67,7 @@
 def has_directed_option(options: dict) -> bool:
     return options.get("System`DirectedEdges", False).to_python()
 
+
 def _process_graph_options(g, options: dict) -> None:
     """
     Handle common graph-related options like VertexLabels, PlotLabel, VertexShape, etc.
@@ -85,6 +94,14 @@ def _process_graph_options(g, options: dict) -> None:
         else "Blue"
     )
 
+    g.graph_layout = (
+        options["System`GraphLayout"].get_string_value()
+        if "System`GraphLayout" in options
+        else ""
+    )
+
+    g.G.graph_layout = g.graph_layout = WL_LAYOUT_TO_MATPLOTLIB.get(g.graph_layout, g.graph_layout)
+
     g.G.node_color = g.node_color = WL_COLOR_TO_MATPLOTLIB.get(color, color)
 
     g.G.title = g.title = (
@@ -834,6 +851,7 @@ def apply_1(self, vertices, edges, evaluation, options):
             edges.leaves, options=options, new_vertices=vertices.leaves
         )
 
+
 class PathGraphQ(_NetworkXBuiltin):
     """
     >> PathGraphQ[Graph[{1 -> 2, 2 -> 3}]]
@@ -1502,7 +1520,7 @@ def apply(self, graph, expression, evaluation, options):
             )
             return Expression(
                 "List",
-                *[Real(centrality.get(v, 0.0)) for v in graph.vertices.expressions]
+                *[Real(centrality.get(v, 0.0)) for v in graph.vertices.expressions],
             )
 
 
@@ -1526,7 +1544,7 @@ def apply(self, graph, expression, evaluation, options):
             centrality = nx.closeness_centrality(G, distance=weight, wf_improved=False)
             return Expression(
                 "List",
-                *[Real(centrality.get(v, 0.0)) for v in graph.vertices.expressions]
+                *[Real(centrality.get(v, 0.0)) for v in graph.vertices.expressions],
             )
 
 
@@ -1546,7 +1564,7 @@ def _from_dict(self, graph, centrality):
         s = len(graph.G) - 1  # undo networkx's normalization
         return Expression(
             "List",
-            *[Integer(s * centrality.get(v, 0)) for v in graph.vertices.expressions]
+            *[Integer(s * centrality.get(v, 0)) for v in graph.vertices.expressions],
         )
 
     def apply(self, graph, expression, evaluation, options):
@@ -1685,7 +1703,7 @@ def apply_alpha_beta(self, graph, alpha, expression, evaluation, options):
             centrality = nx.pagerank(G, alpha=py_alpha, weight=weight, tol=1.0e-7)
             return Expression(
                 "List",
-                *[Real(centrality.get(v, 0)) for v in graph.vertices.expressions]
+                *[Real(centrality.get(v, 0)) for v in graph.vertices.expressions],
             )
 
 
@@ -1775,7 +1793,7 @@ def apply_s_t(self, graph, s, t, expression, evaluation, options):
                 weight = graph.update_weights(evaluation)
                 return Expression(
                     "List",
-                    *list(nx.shortest_path(G, source=s, target=t, weight=weight))
+                    *list(nx.shortest_path(G, source=s, target=t, weight=weight)),
                 )
             except nx.exception.NetworkXNoPath:
                 return Expression("List")

pymathics/graph/generators.py

@@ -45,7 +45,9 @@ def graph_helper(
     except MemoryError:
         evaluation.message(self.get_name(), "mem", expression)
         return None
-    G.graph_layout = options["System`GraphLayout"].get_string_value() or graph_layout
+    if graph_layout and not options["System`GraphLayout"].get_string_value():
+        options["System`GraphLayout"] = String(graph_layout)
+
     g = Graph(G)
     _process_graph_options(g, options)
 
@@ -619,3 +621,29 @@ def apply(self, n, expression, evaluation, options):
             return None
         g.G.n = n
         return g
+
+WL_TO_NETWORKX_FN = {
+    "DodecahedralGraph": (nx.dodecahedral_graph, None),
+    "DiamondGraph": (nx.diamond_graph, "spring"),
+    "PappusGraph": (nx.pappus_graph, "circular"),
+    "IsohedralGraph": (nx.icosahedral_graph, "spring"),
+    "PetersenGraph": (nx.petersen_graph, None),
+}
+
+class GraphData(_NetworkXBuiltin):
+    """
+    <dl>
+      <dt>'GraphData[$name$]'
+      <dd>Returns a graph with the specified name.
+    </dl>
+
+    >> GraphData["PappusGraph"]
+    """
+    def apply(self, name, expression, evaluation, options):
+        "%(name)s[name_String, OptionsPattern[%(name)s]]"
+        py_name = name.get_string_value()
+        fn, layout = WL_TO_NETWORKX_FN.get(py_name, (None, None))
+        if fn:
+            g = graph_helper(fn, options, False, layout)
+            g.G.name = py_name
+            return g