I encountered this problem before when I was doing a for loop, where the second layer of the loop is , ncol=3, so here the loop is going to be for(j in 1:2) and then the assignment matrix is the following error.

After
, it was found on the Internet that the error was caused by improper alignment of array or matrix or out-of-bounds subscripts. After checking the code, it was found that there was indeed a small error, that is, for(j in 1:ncol-1) is equivalent to for(j in 0:1). Obviously, an error will be reported when assigning the value. for(j in 1: ncol-1)) correct.