how to make a list for 3 dimensional data in R

Question

i have a issue related to list()
i need to use 3 for loops to process data just like this

for(i in 1:10){  #it is number of data group
 for(j in 1:5){  #it is number of sub-data group
  for(k in 1:2){ #it is number of sub-data group
     1.data process<br>
     2.just want to make a list within information of i, j ,k

      mylist[i][j][k]

     #i tested some methods like this, but it does not work well<br>
 }
 }
}

Could you give me any ideas or solutions for this issue? Thank you

Answer 1

It's unclear exactly what is necessary, but a multi-dimensionsal collection of non-atomic objects could be done like this:

lst <- lapply(1:10, function(i) {
  lapply(1:5, function(k) {
    lapply(1:2, function(k) {
      # do something here
      lm(mpg ~ cyl, data = mtcars)
    })
  })
})

Now to access the [i,j,k]th element, for example to get the summary of the linear model just made:

i <- 3; j <- 2; k <- 1
summary(lst[[i]][[j]][[k]])

If you absolutely must create it with for loops (not recommended), it's recommended that you pre-populate an empty structure and fill in the holes:

lst <- replicate(10, replicate(5, replicate(2, NULL, simplify = FALSE), simplify = FALSE), simplify = FALSE)
for (i in 1:10) {
  for (j in 1:5) {
    for (k in 1:2) {
      lst[[i]][[j]][[k]] <- ...
    }
  }
}