greedyGraphColoring added

Author: shadowsaber16

Diff for: graphColoringAlgo/greedyGraphColoring/greedyGraphColoring.py

@@ -0,0 +1,45 @@
+import random
+import itertools
+import networkx as nx
+import numpy as np
+import matplotlib.pyplot as plt
+
+def greedyColoringAlgo(network, colors):
+    nodes = list(network.nodes()) 
+    random.shuffle(nodes)
+    for node in nodes:
+        dict_neighbors = dict(network[node])
+        nodes_neighbors = list(dict_neighbors.keys())
+        
+        forbidden_colors = []
+        for neighbor in nodes_neighbors:
+            if len(network.nodes.data()[neighbor].keys()) == 0: 
+                continue
+            else:
+                forbidden_color = network.nodes.data()[neighbor]
+                forbidden_color = forbidden_color['color']                
+                forbidden_colors.append(forbidden_color)
+        for color in colors:
+            if color in forbidden_colors:
+                continue
+            else:
+                network.nodes[node]['color'] = color
+                break
+
+## Create a graph, and an array of colors that has atleast (d+1) colors 
+## Where d is the highest degree of all the vertices.
+
+G = nx.Graph()
+G.add_nodes_from([1, 6])
+G.add_edges_from([(1, 2), (1, 3),(1,4),(1,5),(1,6)])
+G.add_edges_from([(2,3),(2, 4), (2,5),(2,6)])
+G.add_edges_from([(3, 4), (3,5),(3,6)])
+G.add_edges_from([(4,6)])
+colors = ["red", "chocolate", "darkorange", "moccasin", "gold"]
+greedyColoringAlgo(G,colors)
+
+## Visualization of graph can be done by the code below
+colors_nodes = [data['color'] for v, data in G.nodes(data=True)]
+plt.figure(1,figsize=(9,9))  
+nx.draw(G, node_color=colors_nodes, with_labels=True)
+plt.show