Added page-rank algorithm implementation (#780)

* Added page-rank algorithm implementation

* changed init variables
This commit is contained in:
Bhushan Borole 2019-05-12 17:16:47 +05:30 committed by John Law
parent d8badcc6d5
commit 3f7bec6c00

72
Graphs/pagerank.py Normal file
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'''
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()