nomnigraph - easy - expose inducesEdges and addNode to python's NNSubgraph (pytorch#14074)

Summary:
Pull Request resolved: pytorch#14074

expose inducesEdges and addNode to python's NNSubgraph. This make it easy to manually construct a NNSubgraph in python

Reviewed By: bwasti

Differential Revision: D13092885

fbshipit-source-id: a94ed0b318162e27e3a4b5a4954eb6d169da7405

Author: duc0

caffe2/python/nomnigraph_test.py

@@ -96,6 +96,13 @@ def test_edges_simple(self):
         dfg.createEdge(op, w)
         dfg.createEdge(x, op)
 
+        # subgraph
+        sg = ng.NNSubgraph()
+        sg.addNode(x)
+        sg.addNode(op)
+        sg.induceEdges()
+        assert len(sg) == 2
+
     @given(size=st.sampled_from([10, 50]))
     def test_edges_complex(self, size):
         random.seed(1337)

caffe2/python/pybind_state_nomni.cc

@@ -382,7 +382,14 @@ void addNomnigraphMethods(pybind11::module& m) {
 
   // Subgraph matching API
   py::class_<NNSubgraph> nnsubgraph(m, "NNSubgraph");
-  nnsubgraph.def("__len__", [](NNSubgraph& s) { return s.getNodes().size(); })
+  nnsubgraph.def(py::init<>())
+      .def("__len__", [](NNSubgraph& s) { return s.getNodes().size(); })
+      .def(
+          "addNode",
+          [](NNSubgraph* sg, NNGraph::NodeRef node) { sg->addNode(node); })
+      .def(
+          "induceEdges",
+          [](NNSubgraph* sg) { nom::algorithm::induceEdges(sg); })
       .def_property_readonly(
           "nodes",
           [](NNSubgraph& s) {