How to create a dataframe with nested forloops in r

Question

I would like to create a simple data-frame with a nested for loop.

I would like every possibly assembly of 1:3 for A, B and C using a for loop.

This is what I have so far:

for (A in 1:3) {
  for (B in 1:3) {

output[A,]<-A
  }

  }

This is what I would Like it to look like:

Answer 1

For loop is very slow in R. Try to use expand_grid.

library(tidyr)

expand_grid(
  A = 1,
  B = 1:3,
  C = 1:3
)

# A tibble: 9 x 3
      A     B     C
  <dbl> <int> <int>
1     1     1     1
2     1     1     2
3     1     1     3
4     1     2     1
5     1     2     2
6     1     2     3
7     1     3     1
8     1     3     2
9     1     3     3