Unit test and docs update on Ford Fulkerson Max Flow Min Cut algorithm

README.rst

@@ -119,6 +119,10 @@ Features:
     + Topological Sort (for directed acyclic graph, namely dag)
     + Bellman-Ford (for graph with negative weight as well)
 
+  - MaxFlow MinCut
+
+    + Ford-Fulkerson
+
 * Strings
 
   - String Sorting
@@ -389,7 +393,7 @@ Edge Weighted Graph
 
 .. code-block:: python
 
-    from pyalgs.data_structures.graphs.graph import EdgeWeightGraph
+    from pyalgs.data_structures.graphs.graph import EdgeWeightGraph, Edge
     def create_edge_weighted_graph():
         g = EdgeWeightedGraph(8)
         g.add_edge(Edge(0, 7, 0.16))
@@ -409,7 +413,7 @@ Directed Edge Weighted Graph
 
 .. code-block:: python
 
-    from pyalgs.data_structures.graphs.graph import DirectedEdgeWeightedGraph
+    from pyalgs.data_structures.graphs.graph import DirectedEdgeWeightedGraph, Edge
     def create_edge_weighted_digraph():
         g = DirectedEdgeWeightedGraph(8)
 
@@ -420,6 +424,30 @@ Directed Edge Weighted Graph
         return g
 
 
+Flow Network ( for max-flow min-cut problem)
+
+.. code-block:: python
+
+    from pyalgs.data_structures.graphs.graph import FlowNetwork, FlowEdge
+    def create_flow_network():
+    g = FlowNetwork(8)
+    g.add_edge(FlowEdge(0, 1, 10))
+    g.add_edge(FlowEdge(0, 2, 5))
+    g.add_edge(FlowEdge(0, 3, 15))
+    g.add_edge(FlowEdge(1, 4, 9))
+    g.add_edge(FlowEdge(1, 5, 15))
+    g.add_edge(FlowEdge(1, 2, 4))
+    g.add_edge(FlowEdge(2, 5, 8))
+    g.add_edge(FlowEdge(2, 3, 4))
+    g.add_edge(FlowEdge(3, 6, 16))
+    g.add_edge(FlowEdge(4, 5, 15))
+    g.add_edge(FlowEdge(4, 7, 10))
+    g.add_edge(FlowEdge(5, 7, 10))
+    g.add_edge(FlowEdge(5, 6, 15))
+    g.add_edge(FlowEdge(6, 2, 6))
+    g.add_edge(FlowEdge(6, 7, 10))
+
+    return g
 Algorithms
 ----------
 
@@ -734,6 +762,16 @@ Shortest Path (Bellman-Ford for positive and negative edge graph)
             print('path length is ' + str(dijkstra.path_length_to(v)))
 
 
+MaxFlow MinCut (Ford-Fulkerson)
+
+.. code-block:: python
+
+    from pyalgs.algorithms.graphs.max_flow import FordFulkersonMaxFlow
+    network = create_flow_network()
+    ff = FordFulkersonMaxFlow(network, 0, 7)
+    print('max-flow: '+str(ff.max_flow_value()))
+
+
 Strings
 -------
 
@@ -753,5 +791,7 @@ Substring Search (Brute force)
     ss = BruteForceSubstringSearch('find')
     print(ss.search_in('I can find it here'))
     print(ss.search_in('It is not here'))
+
+
 .. _`docs`: http://pyalgs.readthedocs.org/en/latest/
 .. _`documentation`: http://pyalgs.readthedocs.org/en/latest/

docs/algorithms-graphs.rst

@@ -11,4 +11,5 @@ Graphs
    graphs-topological-sort
    graphs-cyclic
    graphs-mst
-   graphs-shortest-path
+   graphs-shortest-path
+   graphs-max-flow

docs/graphs-create.rst

@@ -42,7 +42,7 @@ Edge Weighted Graph
 
 .. code-block:: python
 
-    from pyalgs.data_structures.graphs.graph import EdgeWeightGraph
+    from pyalgs.data_structures.graphs.graph import EdgeWeightGraph, Edge
     def create_edge_weighted_graph():
         g = EdgeWeightedGraph(8)
         g.add_edge(Edge(0, 7, 0.16))
@@ -62,7 +62,7 @@ Directed Edge Weighted Graph
 
 .. code-block:: python
 
-    from pyalgs.data_structures.graphs.graph import DirectedEdgeWeightedGraph
+    from pyalgs.data_structures.graphs.graph import DirectedEdgeWeightedGraph, Edge
     def create_edge_weighted_digraph():
         g = DirectedEdgeWeightedGraph(8)
 
@@ -75,3 +75,30 @@ Directed Edge Weighted Graph
         g.add_edge(
             Edge(1, 2, 12.0))
         return g
+
+
+Flow Network ( for max-flow min-cut problem)
+--------------------------------------------
+
+.. code-block:: python
+
+    from pyalgs.data_structures.graphs.graph import FlowNetwork, FlowEdge
+    def create_flow_network():
+    g = FlowNetwork(8)
+    g.add_edge(FlowEdge(0, 1, 10))
+    g.add_edge(FlowEdge(0, 2, 5))
+    g.add_edge(FlowEdge(0, 3, 15))
+    g.add_edge(FlowEdge(1, 4, 9))
+    g.add_edge(FlowEdge(1, 5, 15))
+    g.add_edge(FlowEdge(1, 2, 4))
+    g.add_edge(FlowEdge(2, 5, 8))
+    g.add_edge(FlowEdge(2, 3, 4))
+    g.add_edge(FlowEdge(3, 6, 16))
+    g.add_edge(FlowEdge(4, 5, 15))
+    g.add_edge(FlowEdge(4, 7, 10))
+    g.add_edge(FlowEdge(5, 7, 10))
+    g.add_edge(FlowEdge(5, 6, 15))
+    g.add_edge(FlowEdge(6, 2, 6))
+    g.add_edge(FlowEdge(6, 7, 10))
+
+    return g

docs/graphs-max-flow.rst

@@ -0,0 +1,13 @@
+Max-Flow-Min-Cut
+================
+
+MaxFlow MinCut (Ford-Fulkerson)
+-------------------------------
+
+.. code-block:: python
+
+    from pyalgs.algorithms.graphs.max_flow import FordFulkersonMaxFlow
+    network = create_flow_network()
+    ff = FordFulkersonMaxFlow(network, 0, 7)
+    print('max-flow: '+str(ff.max_flow_value()))
+

pyalgs/__init__.py

@@ -7,4 +7,4 @@
     :license: BSD, see LICENSE for more details.
 """
 
-__version__ = '0.0.5'
+__version__ = '0.0.6'

pyalgs/algorithms/graphs/max_flow.py

@@ -42,7 +42,7 @@ def has_augmenting_path(self):
             x = queue.dequeue()
             for e in self.network.adj(x):
                 w = e.other(x)
-                if e.residual_capacity(w) > 0:
+                if e.residual_capacity_to(w) > 0:
                     if not self.marked[w]:
                         self.marked[w] = True
                         self.edgeTo[w] = e

pyalgs/data_structures/graphs/graph.py

@@ -240,8 +240,8 @@ def adj(self, v):
         return self.adjList[v].iterate()
 
     def add_edge(self, edge):
-        self.adjList[edge.start()] = edge
-        self.adjList[edge.end()] = edge
+        self.adjList[edge.start()].add(edge)
+        self.adjList[edge.end()].add(edge)
 
     def vertex_count(self):
         return self.V
@@ -250,6 +250,6 @@ def edges(self):
         for v in range(self.V):
             for e in self.adjList[v].iterate():
                 if e.start() == v:
-                    yield e 
+                    yield e
 
 

tests/algorithms/graphs/max_flow_unit_test.py

@@ -0,0 +1,15 @@
+import unittest
+
+from pyalgs.algorithms.graphs.max_flow import FordFulkersonMaxFlow
+from tests.algorithms.graphs.util import create_flow_network
+
+
+class FordFulkersonMaxFlowUnitTest(unittest.TestCase):
+    def test_max_flow(self):
+        network = create_flow_network()
+        ff = FordFulkersonMaxFlow(network, 0, 7)
+        print('max-flow: '+str(ff.max_flow_value()))
+        self.assertEqual(28, ff.max_flow_value())
+
+if __name__ == '__main__':
+    unittest.main()

tests/algorithms/graphs/util.py

@@ -1,5 +1,5 @@
 from pyalgs.data_structures.graphs.graph import Graph, Digraph, EdgeWeightedGraph, Edge, EdgeWeightedGraph, \
-    DirectedEdgeWeightedGraph
+    DirectedEdgeWeightedGraph, FlowNetwork, FlowEdge
 
 
 def create_graph():
@@ -167,3 +167,24 @@ def create_digraph_4_strongly_connected_components():
     graph.add_edge(7, 6)
 
     return graph
+
+
+def create_flow_network():
+    g = FlowNetwork(8)
+    g.add_edge(FlowEdge(0, 1, 10))
+    g.add_edge(FlowEdge(0, 2, 5))
+    g.add_edge(FlowEdge(0, 3, 15))
+    g.add_edge(FlowEdge(1, 4, 9))
+    g.add_edge(FlowEdge(1, 5, 15))
+    g.add_edge(FlowEdge(1, 2, 4))
+    g.add_edge(FlowEdge(2, 5, 8))
+    g.add_edge(FlowEdge(2, 3, 4))
+    g.add_edge(FlowEdge(3, 6, 16))
+    g.add_edge(FlowEdge(4, 5, 15))
+    g.add_edge(FlowEdge(4, 7, 10))
+    g.add_edge(FlowEdge(5, 7, 10))
+    g.add_edge(FlowEdge(5, 6, 15))
+    g.add_edge(FlowEdge(6, 2, 6))
+    g.add_edge(FlowEdge(6, 7, 10))
+
+    return g