python - 如何纠正计算加权页面排名时获得的 NaN 值？

Question

我正在尝试计算图表的加权页面排名。对于此计算，我使用以下代码：

import numpy as np
from scipy.sparse import csc_matrix
import random

def column(matrix, i):
      return [row[i] for row in matrix]

def pageRank(G, s = 0.85, maxerr = .001):
 
      n = G.shape[0]

      M = csc_matrix(G,dtype=np.float)
      rsums = np.array(M.sum(1))[:,0]
      ri, ci = M.nonzero()
      M.data /= rsums[ri]

      sink = rsums==0

      # Compute pagerank r until we converge

      ro, r = np.zeros(n), np.ones(n)
      while np.sum(np.abs(r-ro)) > maxerr:
            ro = r.copy()
            # calculate each pagerank at a time
            for i in range(0,n):
                 # inlinks of state i
                 Ii = np.array(M[:,i].todense())[:,0]
                 # account for sink states
                 Si = sink / float(n)
                 # account for teleportation to state i
                 Ti = np.ones(n) / float(n)
                 # Weighted PageRank Equation
                 r[i] = ro.dot( Ii*s + Si*s*G[i] + Ti*(1-s)) 


       # return normalized pagerank
       return r/sum(r)



 if __name__=='__main__':

 G = np.array([[0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0], [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0], 
      [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0], [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0], 
      [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0],
      [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0], [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0],
      [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0], [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0],
      [0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0],
      [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0],
      [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0]])



 print(pageRank(G,s = 1))
 print(G)

以下代码的输出是：

 [nan nan nan nan nan nan nan nan nan nan nan nan nan nan nan]

但是，当为这样的不同图表完成时：

 [[1,1,0,0,0,0,0],
  [1,1,0,0,0,0,0],
  [0,0,1,0,0,0,0],
  [0,0,0,1,0,0,0],
  [0,0,0,0,1,0,0],
  [0,0,0,0,0,0,0],
  [0,0,0,0,0,1,1]]

获得以下输出：

   [1.99979908e-01 1.99979908e-01 1.99979908e-01 1.99979908e-01
    1.99979908e-01 5.02299201e-05 5.02299201e-05]

谁能指出我做错了什么或需要如何修改代码？谢谢！

标签： pythonpagerank