Merge pull request #1790 from networkx/dschult-patch-3

Rewrite harmonic_centrality to better use iterator

1 files changed, 11 insertions, 19 deletions

diff --git a/networkx/algorithms/centrality/harmonic.py b/networkx/algorithms/centrality/harmonic.py
index 76f692a3..62ba653b 100644
--- a/networkx/algorithms/centrality/harmonic.py
+++ b/networkx/algorithms/centrality/harmonic.py
@@ -52,27 +52,19 @@ def harmonic_centrality(G, distance=None):
 
     References
     ----------
-    .. [1] Boldi, Paolo, and Sebastiano Vigna. "Axioms for centrality." Internet Mathematics 10.3-4 (2014): 222-262.
+    .. [1] Boldi, Paolo, and Sebastiano Vigna. "Axioms for centrality."
+           Internet Mathematics 10.3-4 (2014): 222-262.
     """
-
+    if len(G) <= 1:
+        return {singleton: 0.0 for singleton in G.nodes()}
+    
+    if G.is_directed():
+        G = G.reverse()
+        
     if distance is not None:
         # use Dijkstra's algorithm with specified attribute as edge weight
-        path_length = functools.partial(nx.all_pairs_dijkstra_path_length,
-                                        weight=distance)
+        sp = nx.all_pairs_dijkstra_path_length(G, weight=distance)
     else:
-        path_length = nx.all_pairs_shortest_path_length
-
-    nodes = G.nodes()
-    harmonic_centrality = {}
-
-    if len(G) <= 1:
-        for singleton in nodes:
-            harmonic_centrality[singleton] = 0.0
-        return harmonic_centrality
-
-    sp = path_length(G.reverse() if G.is_directed() else G)
-    for node, dist_dict in sp:
-            harmonic_centrality[node] = sum(
-                [1/dist if dist > 0 else 0 for dist in dist_dict.values()])
+        sp = nx.all_pairs_shortest_path_length(G)
 
-    return harmonic_centrality
+    return {n: sum(1/d if d > 0 else 0 for d in dd.values()) for n, dd in sp}