gistfile1.py

#!/usr/bin/env python
# HITS (on memory)
 
from numarray import *
from numarray.matrix import *
 
EPS = 1.0e-10
 
class HITS():
    def __init__(self, adj_matrix):
        self._cnt = 0
        self._err = 0
        self._dim = adj_matrix[0].size()
        self._adj = adj_matrix
 
    def calc(self):
        self._cnt = 0
        auth = ones( self._dim, Float64 )
        hub = ones( self._dim, Float64 )
        while 1:
            self._cnt += 1
            auth_prev = auth
            hub_prev = hub
 
            temp_auth = dot(transpose(self._adj), hub)
            auth = 1. / sum(temp_auth) * temp_auth
            temp_hub = dot(self._adj, auth)
            hub = 1. / sum(temp_hub) * temp_hub
            self._err = self.diff(auth, auth_prev, hub, hub_prev)
            if (self._err < EPS): break
        return (auth, hub)
 
    def diff(self, a, a_, h, h_):
        err = 0
        for i in range(self._dim):
            err += absolute(h_[i] - h[i])
            err += absolute(a_[i] - a[i])
        return err
 
 
Adj = Matrix([array([0, 0, 1, 1]),
              array([0, 0, 1, 1]),
              array([1, 1, 0, 0]),
              array([0, 1, 1, 0])])
 
hits = HITS(Adj)
(auth,hub) = hits.calc()
print "auth:", auth
print "hub:", hub
print "error:", hits._err
print "iteration:", hits._cnt