Python/graphs/page_rank.py
2019-10-05 10:14:13 +05:00

73 lines
1.5 KiB
Python

"""
Author: https://github.com/bhushan-borole
"""
"""
The input graph for the algorithm is:
A B C
A 0 1 1
B 0 0 1
C 1 0 0
"""
graph = [[0, 1, 1], [0, 0, 1], [1, 0, 0]]
class Node:
def __init__(self, name):
self.name = name
self.inbound = []
self.outbound = []
def add_inbound(self, node):
self.inbound.append(node)
def add_outbound(self, node):
self.outbound.append(node)
def __repr__(self):
return "Node {}: Inbound: {} ; Outbound: {}".format(
self.name, self.inbound, self.outbound
)
def page_rank(nodes, limit=3, d=0.85):
ranks = {}
for node in nodes:
ranks[node.name] = 1
outbounds = {}
for node in nodes:
outbounds[node.name] = len(node.outbound)
for i in range(limit):
print("======= Iteration {} =======".format(i + 1))
for j, node in enumerate(nodes):
ranks[node.name] = (1 - d) + d * sum(
[ranks[ib] / outbounds[ib] for ib in node.inbound]
)
print(ranks)
def main():
names = list(input("Enter Names of the Nodes: ").split())
nodes = [Node(name) for name in names]
for ri, row in enumerate(graph):
for ci, col in enumerate(row):
if col == 1:
nodes[ci].add_inbound(names[ri])
nodes[ri].add_outbound(names[ci])
print("======= Nodes =======")
for node in nodes:
print(node)
page_rank(nodes)
if __name__ == "__main__":
main()