我有一个很大的矩阵,我想从其中随机提取一个较小的矩阵。(我想这样做1000次,所以最终它将在for循环中。)举个例子,我有一个9x9矩阵:
mat=matrix(c(0,0,1,0,1,0,0,0,1,0,0,0,0,1,1,1,0,0,1,0,1,0,0,0,0,0,1,0,1,0,0,0,1,
0,0,0,0,1,1,1,0,0,1,0,1,0,0,0,0,0,1,0,1,0,0,0,1,0,0,0,0,1,1,1,0,0,
1,0,1,0,0,0,0,0,1,0,1,0,0,0,1), nrow=9)
从这个矩阵中,我想要一个随机的3x3子集。诀窍