生成一個稀疏行隨機矩陣？

Question

我試圖用Matlab生成一個稀疏隨機矩陣，但目前遇到問題。這是我目前在的地方。

N=10 
i = round(rand(1,N)*10)+1 
j = round(rand(1,N)*10)+1 

S1 = sparse (i,j,1,N,N); 
S = full(S1) 

rowsum = sum(S,2); 
S = bsxfun(@rdivide, S, rowsum); 

現在這最後一行是失敗的地方。稀疏矩陣中有一些零行。

所以我的問題是我如何規範化每行還保留零行？

Answer 1

這是一個非常簡單的模型我會用：

%logical matrix, a web page links to 20% of the other websites on average. This is a strange model, but I don't have a better idear: 
doeslink=rand(N)<.2.*1-eye(N) 
%generate random link weights 
S=rand(N).*doeslink 
%avoid nans 
rowsum(rowsum==0)=1 
%normalise 
S = bsxfun(@rdivide, S, rowsum);