added degree centrality, fixed closeness definition

pathpy/algorithms/centralities.py

@@ -76,6 +76,51 @@ def rank_centralities(centralities):
     return ranked_nodes
 
 
+def degree(network, mode='degree'):    
+    """
+    Calculates different notions of degree centrality (directed, weighted) in a network
+
+    Parameters:
+    -----------
+
+    mode: str
+        'degree'
+        'weight'
+        'indegree'
+        'inweight'
+        'outdegree'
+        'outweight'
+    """
+
+    assert mode == 'degree' or mode == 'weight' or mode == 'indegree' or mode == 'outdegree' \
+            or mode == 'inweight' or mode == 'outweight', 'Error: Invalid mode'
+
+    degree_centralities = defaultdict(lambda: 0.0)
+
+    for n in network.nodes:
+        # undirected network: only distinguish between degree and weighted degree
+        if not network.directed and (mode == 'degree' or mode == 'outdegree' or mode == 'indegree'):
+            degree_centralities[n] = float(network.nodes[n]['degree'])
+        if not network.directed and (mode == 'weight' or mode == 'outweight' or mode == 'inweight'):
+            degree_centralities[n] = float(network.nodes[n]['inweight'])
+
+        # directed network: distinguish between degree, weighted degree, inweight, outweight, indegree and outdegree
+        if network.directed and mode == 'degree':
+            degree_centralities[n] = float(network.nodes[n]['indegree'])
+            degree_centralities[n] += float(network.nodes[n]['outdegree'])
+        if network.directed and mode == 'weight':
+            degree_centralities[n] = float(network.nodes[n]['inweight'])
+            degree_centralities[n] += float(network.nodes[n]['outweight'])
+        elif network.directed and mode == 'indegree':
+            degree_centralities[n] = float(network.nodes[n]['indegree'])
+        elif network.directed and mode == 'outdegree':
+            degree_centralities[n] = float(network.nodes[n]['outdegree'])
+        elif network.directed and mode == 'inweight':
+            degree_centralities[n] = float(network.nodes[n]['inweight'])
+        elif network.directed and mode == 'outweight':
+            degree_centralities[n] = float(network.nodes[n]['outweight'])
+    return degree_centralities
+
 
 @singledispatch
 def betweenness(network, normalized=False):
@@ -261,14 +306,16 @@ def closeness(network, normalized=False):
     Log.add('Calculating closeness in network ...', Severity.INFO)
 
     # calculate closeness values
-    for x in network.nodes:
-        for d in network.nodes:
+    for d in network.nodes:
+        for x in network.nodes:
             if d != x and distances[d][x] < _np.inf:
-                node_centralities[x] += 1.0 / distances[d][x]
+                node_centralities[x] += distances[d][x]
 
     # assign centrality zero to nodes not occurring on higher-order shortest paths
     for v in network.nodes:
-        node_centralities[v] += 0
+        node_centralities[v] += 0.0
+        if node_centralities[v] > 0.0:
+            node_centralities[v] = (network.ncount() - 1.0) / node_centralities[v]
 
     if normalized:
         max_centr = max(node_centralities.values())

pathpy/classes/network.py

@@ -86,8 +86,7 @@ def __add__(self, other):
         Network
             Default operator +, which returns the sum of two Network objects
         """
-        n_sum = Network()
-        n_sum.directed = self.directed
+        n_sum = Network(directed = self.directed or other.directed)
         n_sum.nodes = copy.deepcopy(self.nodes)
         n_sum.edges = copy.deepcopy(self.edges)
         n_sum.successors = copy.deepcopy(self.successors)
@@ -532,9 +531,9 @@ def total_edge_weight(self):
 
     def node_properties(self, prop):
         """
-        Returns a sequence of arbitrary node properties in the network, 
+        Returns a list of arbitrary node properties in the network, 
         where entries have the same order as in network.nodes. If a property
-        is not present for a given node, None will be added to the sequence.
+        is not present for a given node, None will be added to the list.
         """
         properties = []
         for v in self.nodes:
@@ -548,7 +547,9 @@ def node_properties(self, prop):
     def degrees(self, mode='degree'):
         """
         Returns the sequence of node degrees in the network, where
-        entries have the same order as in network.nodes.
+        entries have the same order as in network.nodes. Note that 
+        if mode == 'degree' for a directed network, the degree sequence
+        of the undirected network will be returned.
 
         Parameters:
         -----------
@@ -557,6 +558,10 @@ def degrees(self, mode='degree'):
         """
         assert mode is 'degree' or mode is 'indegree' or mode is 'outdegree', \
             'Only "degree", "indegree", or "outdegree" are supported.'
+
+        if self.directed and mode == 'degree':
+            return self.to_undirected().degrees()
+
         return self.node_properties(mode)