How to extract different list items at the same time

Question

I have a function where its argument is a list. This argument is executed for different values. My original feature is very complicated. Therefore, I posted an example similar to part of my function.

An example here is multiplication (just to show an idea). I think it forcan't work here, because the loop fortakes element by element, while I need to take two different list items at the same time

The whole idea:

how to do this piece of code xxx <- myfun(z[[1]][k,j],z[[2]][k,i]))for an arbilary number of elements, instead of doing it manually. For example, if I have a 3matrix, then I would write code as follows: xxx <- myfun(z[[1]][k,j],z[[2]][k,i], z[[3]][k,j]). How to do this automatically is not manual.

For example, zthis is a list of matrices. I would like to run my function for the specific values ​​of these matrices. That is, every time I would like my function to select certain elements of my matrices. Here is my code:

x <- c(0,1,2,
       0,0,1,
       0,0,0)
x <- matrix(x,3,3)

y <- c(0,2,3,
       0,0,1,
       0,0,0)
y <- matrix(y,3,3)
z <- list(x,y)



     myfun <- function(f=list()){
  s <- length(f)
  xy <- list()
  for(i in 1:s){
    xy[[i]] <- 2*f[[i]]

  }
  xy
}

Here is my attempt.

note that

Here, I would like to take certain function values of the matrices xand yand insert them in the list of my function. I would like it to work for an arbitrary number of list items. That is, sometimes I have matrices 3or 4. Therefore, the number of matrices is not fixed.

## I try the following and it works great, however, how to make it work for any number of elements.

 xxx <- list()
for(i in 1:2){
for(k in 1:3){
  for(j in 1:3){
    xxx[[i]] <- myfun(f=list(z[[1]][1,2],z[[2]][1,2]))
  }
}
}

Any help please?

Answer 1

, xxx <- myfun(z[[1]][k,j],z[[2]][k,i], z[[3]][k,j]) ,

, :

xxx <- myfun(f=lapply(z, function(x){x[k,j]}))

k = 1 j = 2

xxx <- myfun(f=lapply(z, function(x){x[1,2]}))

, .