Working on projections

.travis.yml

@@ -2,6 +2,8 @@ language: python
 python:
   - "3.5"
   - "3.6"
+  - "3.7"
+  - "3.8"
 install:
   - pip install --upgrade pip
   - pip install --upgrade setuptools

experiments/monopartite_projection.py

@@ -0,0 +1,18 @@
+import csv
+from networkx import Graph
+from fog.graph import cosine_monopartite_projection
+
+bipartite = Graph()
+
+with open('./data/bipartite.csv') as f:
+    reader = csv.DictReader(f)
+
+    for line in reader:
+        account = 'a%s' %line['account']
+        url = 'u%s' % line['url']
+
+        bipartite.add_node(account, type='account')
+        bipartite.add_node(url, type='url')
+        bipartite.add_edge(account, url, weight=int(line['weight']))
+
+monopartite = cosine_monopartite_projection(bipartite, 'account', part='type')

fog/graph/__init__.py

@@ -0,0 +1,3 @@
+from fog.graph.projection import (
+    cosine_monopartite_projection
+)

fog/graph/projection.py

@@ -4,7 +4,30 @@
 #
 # Miscellaneous functions related to bipartite to monopartite projections.
 #
+from collections import defaultdict, Counter
+from networkx import Graph
 
 
-def cosine_monopartite_projection():
-    pass
+def cosine_monopartite_projection(bipartite, keep, part='bipartite', weight='weight',
+                                  threshold=None):
+    monopartite = Graph()
+
+    vectors = defaultdict(Counter)
+
+    for n1, n2, w in bipartite.edges(data=weight, default=1):
+        p1 = bipartite.nodes[n1][part]
+        p2 = bipartite.nodes[n2][part]
+
+        assert p1 != p2, 'fog.graph.cosine_monopartite_projection: given graph is not truly bipartite.'
+
+        # Swapping so n1 is from part to keep
+        if p2 == part:
+            n1, n2 = n2, n1
+
+        vectors[n1][n2] += w
+
+    norms = {}
+
+    for node, vector in vectors.items():
+        monopartite.add_node(node, bipartite.nodes[node])
+        norms[node] = sum(vector.values())

requirements.txt

@@ -9,6 +9,6 @@ twine==1.11.0
 
 # Dependencies
 dill==0.2.7.1
-networkx==2.5
+networkx>=2
 phylactery==0.1.1
 Unidecode==1.0.22