CODEWITHSUNDEEP
r
rose
rose

Reputation: 1981

replacement and two for loop in R

I would like to have a vector res with length 200, which includes 20 times repetition of random generation values divided by 2 which is r[i], how can I get this in R?I wrote the following code but it is just save each iteration values,not the whole iterations.

r = rep(0, 10)
res = matrix(0, nrow=200, ncol=1)
for(j in 1:20){
  for(i in 1:10){
    x = rnorm(10, 0, 1)
    r[i] = x/2
  }
  res = rbind(r)
}

Upvotes: 0

Views: 70

Answers (1)

iugrina
iugrina

Reputation: 605

as Roland said in a comment to your question writing two loops for this isn't a good practice. However, you can do it like this

res = rep(0, 200)
r = rep(0, 10)
for(j in 1:20){
    for(i in 1:10){
        x = rnorm(1, 0, 1)
        r[i] = x/2
    }
    res[((j-1)*10+1):(j*10)] = r
}

As for your solution, there were some problems:

  1. There is no need to define a matrix res = matrix(0, nrow=200, ncol=1) if you only need a vector
  2. rnorm(10,0,1) returns a vector of 10 values so assigning it to r[i] (which takes only one value) isn't correct
  3. rbind is used to connect two vectors/matrices/... by rows so using it with only one parameter doesn't really make a sense here

Upvotes: 2

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