How can I make a map with defined density in random arrangement.

Pls refer to this image

Program as listed: Map=zeros(100,80); Rn=rand(size(Map)); Rn=Rn>0.8; % to define the density (possibility) 0.2 b=find(Rn==1); Map(b)=1;

Question is: Is any suggested method to avoid the connected points?