added basic network plotting

bindings/python/cntk/graph.py

@@ -29,6 +29,66 @@ def dfs_walk(node, visitor, accum, visited):
     if visitor(node):
         accum.append(node)
 
+
+def build_graph(node, visitor, accum, visited, dot_object):
+    '''
+    Generic function to build the graph.
+
+    Args:
+        node (graph node): the node to start the journey from
+        visitor (Python function or lambda): function that takes a node as
+         argument and returns `True` if that node should be returned.
+        accum (`list`): accumulator of nodes while traversing the graph
+        visited (`set`): set of nodes that have already been visited.
+         Initialize with empty set.
+        dot_object(`Pydot.Dot`): contains the graph description in 
+         dot format
+    '''
+    import pydot
+    if node in visited:
+        return
+    visited.add(node)
+
+    if hasattr(node, 'root_function'):
+        node = node.root_function
+        cur_node = pydot.Node(node.op_name+' '+node.uid, label=node.op_name)
+        dot_object.add_node(cur_node)
+        out_node = pydot.Node(node.outputs[0].uid, label=node.outputs[0].uid 
+                                + '\nshape:\n' + str(node.outputs[0].shape))
+        dot_object.add_node(out_node)
+        dot_object.add_edge(pydot.Edge(cur_node,out_node))
+        for child in node.inputs:
+            child_node = pydot.Node(child.uid, label=child.uid + '\nshape:\n' + str(child.shape))
+            dot_object.add_node(child_node)
+            dot_object.add_edge(pydot.Edge(child_node, cur_node))
+            dfs_walk_plot(child, visitor, accum, visited, dot_object)
+
+    elif hasattr(node, 'is_output') and node.is_output:
+        dfs_walk_plot(node.owner, visitor, accum, visited, dot_object)
+
+    if visitor(node):
+        accum.append(node)
+ 
+
+def png_graph(model, path):
+    '''
+    Saves the network graph to the file
+
+    Args:
+        model(`cntk.ops.functions.Function`): model to plot
+        path(`str`): path to the save directory
+    '''
+    import pydot
+    dot_object = pydot.Dot(graph_name="network_graph",rankdir='LR')
+    dot_object.set_node_defaults(shape='circle', fixedsize='false',
+                             height=.85, width=.85, fontsize=10)
+
+    accum = []
+    dfs_walk_plot(model, lambda x: True, accum, set(), dot_object)
+    dot_object.write_png(path + '\\network_graph.png', prog='dot')
+
+
+
 def visit(node, visitor):
     '''
     Generic function that walks through the graph starting at `node` and