双循环随机采样

Question

I wanted to generate score i (0:36) with frequency j . I wanted j loop to be random numbers. What I did was:

j<-1:70
for(i in 0:36) {
  for (j in 1:sample(j)) {
    print(i,j)
  }
}

But I got error. Should have I put sample(j,1, replacement=TRUE) instead of just sample(j) ? thank you

Answer 1

If I understand correctly, you want each element in i replicated from one to 70 times (randomly choosing the number of times to replicate the value).

i <- 0:36
j <- 1:70

#number of times to replicate each i
times <- sample(j, length(i), replace=FALSE)
result <- rep(i, times)

Whether to use replace=FALSE or not depends on how you'd like the sampling done (eg replace=FALSE assures that each j is chosen at most one time.

Answer 2

If you want a random number, you should use runif . It has min/max to control the range. You can also use sample , but then it's better to use sample.int(max, 1)

j<-70
for(i in 0:36) {
  for (k in 1:runif(1,1,j)) {
    cat(i,k, "\n")
  }
}

Then the inner loop shouldn't overwrite j (which should be a constant) - so I renamed the loop variable to k . ...and print doesn't print multiple args like that - but cat does!

Answer 3

Try

for(i in 0:36) {
  for(k in 1:sample(70, 1)) {
    print(c(i,k))
  }
}