Use pydot to layout the graph

dream/platform/__init__.py

 import json
 import traceback
 import multiprocessing
+import pydot
 
 from flask import Flask, jsonify, redirect, url_for
 from flask import request
@@ -16,6 +17,39 @@ def front_page():
   return redirect(url_for('static', filename='index.html'))
 
 
+@app.route("/positionGraph", methods=["POST", "OPTIONS"])
+def positionGraph():
+  """Uses graphviz to position nodes of the graph.
+  """
+  graph = pydot.Dot()
+
+  for node in request.json['element'].itervalues():
+    graph.add_node(pydot.Node(node['id']))
+    for successor in node.get('successorList', []):
+      graph.add_edge(pydot.Edge(node['id'], successor))
+
+  new_graph = pydot.graph_from_dot_data(graph.create_dot())
+
+  # calulate the ratio from the size of the bounding box
+  ratio = new_graph.get_bb()
+  origin_left, origin_top, max_left, max_top = [float(p) for p in
+    new_graph.get_bb()[1:-1].split(',')]
+  ratio_top = max_top - origin_top
+  ratio_left = max_left - origin_left
+
+  preference_dict = dict()
+  for node in new_graph.get_nodes():
+    # skip technical nodes
+    if node.get_name() in ('graph', 'node', 'edge'):
+      continue
+    left, top = [float(p) for p in node.get_pos()[1:-1].split(",")]
+    preference_dict[node.get_name()[1:-1]] = dict(
+      top=1-(top/ratio_top),
+      left=1-(left/ratio_left),)
+
+  return jsonify(preference_dict)
+
+
 @app.route("/runSimulation", methods=["POST", "OPTIONS"])
 def runSimulation():
   parameter_dict = request.json['json']

setup.py

@@ -12,6 +12,8 @@ setup(
         'SimPy>=2,<3',
         'xlrd',
         'xlwt',
+        'pyparsing==1.5.7',
+        'pydot',
     ],
     entry_points=("""
     [console_scripts]