Python/graphs/page_rank.py

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