sorting/ rearranging data list in R

Question

I have a list (l):

[1] 0 0 0 1 1 1 2 2 2

[2] 0 0 0 1 1 1 2 2 2

[3] 0 0 0 1 1 1 2 2 2 

and now I want to sort it like this first:

[1] 0 1 2 0 1 2 0 1 2 

[2] 0 1 2 0 1 2 0 1 2 

[3] 0 1 2 0 1 2 0 1 2 

and then:

[1] 0 1 2

[2] 0 1 2

[3] 0 1 2

[4] 0 1 2

[5] 0 1 2

[6] 0 1 2

[7] 0 1 2

[8] 0 1 2

[9] 0 1 2

How can I do this? I have no idea :/ Please help me

Answer 1

We loop through the list of vectors with lapply, create a sequence with ave to order the vector

l1 <- lapply(l, function(x) x[order(ave(x, x, FUN = seq_along))])
l1
#[[1]]
#[1] 0 1 2 0 1 2 0 1 2

#[[2]]
#[1] 0 1 2 0 1 2 0 1 2

#[[3]]
#[1] 0 1 2 0 1 2 0 1 2

Then, we find where the 0 is to split the vector into sub vectors

unname(do.call(c, lapply(l1, function(x) split(x, cumsum(!x)))))
#[[1]]
#[1] 0 1 2

#[[2]]
#[1] 0 1 2

#[[3]]
#[1] 0 1 2

#[[4]]
#[1] 0 1 2

#[[5]]
#[1] 0 1 2

#[[6]]
#[1] 0 1 2

#[[7]]
#[1] 0 1 2

#[[8]]
#[1] 0 1 2

#[[9]]
#[1] 0 1 2

---

Also, if the end result is the goal, this can be done in a single step

unname(split(c(aperm(array(unlist(l), c(3, 3, 3)), c(2, 1, 3))), as.numeric(gl(27, 3, 27))))
#[[1]]
#[1] 0 1 2

#[[2]]
#[1] 0 1 2

#[[3]]
#[1] 0 1 2

#[[4]]
#[1] 0 1 2

#[[5]]
#[1] 0 1 2

#[[6]]
#[1] 0 1 2

#[[7]]
#[1] 0 1 2

#[[8]]
#[1] 0 1 2

#[[9]]
#[1] 0 1 2

data

l <- replicate(3, rep(0:2, each = 3), simplify = FALSE)

Answer 2

You can use lapply and unique to repeat each unique elements multiple times. Here I just show it on two elements, the length of the list does not matter:

my_list <- list(c(0, 0, 0, 1, 1, 1, 2, 2, 2), c(0, 0, 0, 1, 1, 1, 2, 2, 2))

The first sorted list:

## Replicate each unique element in a list
new.list.1 <- function(list) {
    unique_elements <- unique(list)
    rep(unique_elements, length(list)/length(unique_elements))
}

## Apply the function
lapply(my_list, new.list.1)
#[[1]]
#[1] 0 1 2 0 1 2 0 1 2
#
#[[2]]
#[1] 0 1 2 0 1 2 0 1 2

And the second one on the same principle

## Replicate each unique in multiple lists
new.list.2 <- function(list) {
    unique_elements <- unique(list)
    rep(list(unique_elements), length(list)/length(unique_elements))
}

## Apply the function and unlist the nested level
unlist(lapply(my_list, new.list.2), recursive = FALSE)
#[[1]]
#[1] 0 1 2
#
#[[2]]
#[1] 0 1 2
#
#[[3]]
#[1] 0 1 2
#
#[[4]]
#[1] 0 1 2
#
#[[5]]
#[1] 0 1 2
#
#[[6]]
#[1] 0 1 2