Merge pull request #1636 from MridulS/degreeupdate

Add comment about single node test in degree method

4 files changed, 45 insertions, 14 deletions

diff --git a/networkx/classes/digraph.py b/networkx/classes/digraph.py
index b1fbe6f3..7bd0f19c 100644
--- a/networkx/classes/digraph.py
+++ b/networkx/classes/digraph.py
@@ -902,13 +902,16 @@ class DiGraph(Graph):
         [(0, 1), (1, 2)]
 
         """
+        # Test to see if nbunch is a single node, an iterator of nodes or
+        # None(indicating all nodes). (nbunch in self) is True when nbunch
+        # is a single node.
         if nbunch in self:
             succ = self.succ[nbunch]
             pred = self.pred[nbunch]
             if weight is None:
                 return len(succ) + len(pred)
-            return sum(succ[nbr].get(weight, 1) for nbr in succ) + \
-                   sum(pred[nbr].get(weight, 1) for nbr in pred)
+            return sum(data.get(weight, 1) for data in succ.values()) + \
+                   sum(data.get(weight, 1) for data in pred.values())
 
         if nbunch is None:
             nodes_nbrs=( (n,succs,self.pred[n]) for n,succs in self.succ.items())
@@ -922,8 +925,8 @@ class DiGraph(Graph):
             def d_iter():
                 for n,succ,pred in nodes_nbrs:
                     yield (n,
-                      sum((succ[nbr].get(weight,1) for nbr in succ))+
-                      sum((pred[nbr].get(weight,1) for nbr in pred)))
+                      sum((data.get(weight,1) for data in succ.values()))+
+                      sum((data.get(weight,1) for data in pred.values())))
         return d_iter()
 
 
@@ -966,10 +969,14 @@ class DiGraph(Graph):
         [(0, 0), (1, 1)]
 
         """
+        # Test to see if nbunch is a single node, an iterator of nodes or
+        # None(indicating all nodes). (nbunch in self) is True when nbunch
+        # is a single node.
         if nbunch in self:
+            pred = self.pred[nbunch]
             if weight is None:
-                return len(self.pred[nbunch])
-            return sum(self.pred[nbunch][nbr].get(weight, 1) for nbr in self.pred[nbunch])
+                return len(pred)
+            return sum(data.get(weight, 1) for data in pred.values())
 
         if nbunch is None:
             nodes_nbrs=self.pred.items()
@@ -1027,10 +1034,14 @@ class DiGraph(Graph):
         [(0, 1), (1, 1)]
 
         """
+        # Test to see if nbunch is a single node, an iterator of nodes or
+        # None(indicating all nodes). (nbunch in self) is True when nbunch
+        # is a single node.
         if nbunch in self:
+            succ = self.succ[nbunch]
             if weight is None:
-                return len(self.succ[nbunch])
-            return sum(self.succ[nbunch][nbr].get(weight, 1) for nbr in self.succ[nbunch])
+                return len(succ)
+            return sum(data.get(weight, 1) for data in succ.values())
 
         if nbunch is None:
             nodes_nbrs=self.succ.items()
diff --git a/networkx/classes/graph.py b/networkx/classes/graph.py
index 9967953e..442cb95a 100644
--- a/networkx/classes/graph.py
+++ b/networkx/classes/graph.py
@@ -1257,6 +1257,9 @@ class Graph(object):
         >>> list(G.degree([0,1]))
         [(0, 1), (1, 2)]
         """
+        # Test to see if nbunch is a single node, an iterator of nodes or
+        # None(indicating all nodes). (nbunch in self) is True when nbunch
+        # is a single node.
         if nbunch in self:
             nbrs = self.adj[nbunch]
             if weight is None:
diff --git a/networkx/classes/multidigraph.py b/networkx/classes/multidigraph.py
index 4a0eb9f7..d871b33a 100644
--- a/networkx/classes/multidigraph.py
+++ b/networkx/classes/multidigraph.py
@@ -564,6 +564,9 @@ class MultiDiGraph(MultiGraph,DiGraph):
         [(0, 1), (1, 2)]
 
         """
+        # Test to see if nbunch is a single node, an iterator of nodes or
+        # None(indicating all nodes). (nbunch in self) is True when nbunch
+        # is a single node.
         if nbunch in self:
             succ = self.succ[nbunch]
             pred = self.pred[nbunch]
@@ -571,8 +574,9 @@ class MultiDiGraph(MultiGraph,DiGraph):
                 indeg = sum([len(data) for data in pred.values()])
                 outdeg = sum([len(data) for data in succ.values()])
                 return indeg + outdeg
-            s = (sum(sum(succ[nbr][node].get(weight, 1) for node in succ[nbr]) for nbr in succ)) + \
-                (sum(sum(pred[nbr][node].get(weight, 1) for node in pred[nbr]) for nbr in pred))
+            s = (sum(sum(data.get(weight, 1) for data in keydict.values())
+                for keydict in succ.values())) + (sum(sum(data.get(weight, 1)
+                for data in keydict.values()) for keydict in pred.values()))
             return s
 
         if nbunch is None:
@@ -640,10 +644,15 @@ class MultiDiGraph(MultiGraph,DiGraph):
         [(0, 0), (1, 1)]
 
         """
+        # Test to see if nbunch is a single node, an iterator of nodes or
+        # None(indicating all nodes). (nbunch in self) is True when nbunch
+        # is a single node.
         if nbunch in self:
+            pred = self.pred[nbunch]
             if weight is None:
-                return sum(len(self.pred[nbunch][node]) for node in self.pred[nbunch])
-            return (sum(sum(self.pred[nbunch][nbr][node].get(weight, 1) for node in self.pred[nbunch][nbr]) for nbr in self.pred[nbunch]))
+                return sum(len(data) for data in pred.values())
+            return (sum(sum(data.get(weight,1) for data in keydict.values())
+                           for keydict in pred.values()))
         if nbunch is None:
             nodes_nbrs = self.pred.items()
         else:
@@ -702,10 +711,15 @@ class MultiDiGraph(MultiGraph,DiGraph):
         [(0, 1), (1, 1)]
 
         """
+        # Test to see if nbunch is a single node, an iterator of nodes or
+        # None(indicating all nodes). (nbunch in self) is True when nbunch
+        # is a single node.
         if nbunch in self:
+            succ = self.succ[nbunch]
             if weight is None:
-                return sum(len(self.succ[nbunch][node]) for node in self.succ[nbunch])
-            return (sum(sum(self.succ[nbunch][nbr][node].get(weight, 1) for node in self.succ[nbunch][nbr]) for nbr in self.succ[nbunch]))
+               return sum(len(data) for data in succ.values())
+            return (sum(sum(data.get(weight,1) for data in keydict.values())
+                           for keydict in succ.values()))
         if nbunch is None:
             nodes_nbrs = self.succ.items()
         else:
diff --git a/networkx/classes/multigraph.py b/networkx/classes/multigraph.py
index 85d53a62..8337643d 100644
--- a/networkx/classes/multigraph.py
+++ b/networkx/classes/multigraph.py
@@ -755,6 +755,9 @@ class MultiGraph(Graph):
         [(0, 1), (1, 2)]
 
         """
+        # Test to see if nbunch is a single node, an iterator of nodes or
+        # None(indicating all nodes). (nbunch in self) is True when nbunch
+        # is a single node.
         if nbunch in self:
             nbrs = self.adj[nbunch]
             if weight is None: