Remove all lists positions in list of lists after first NA appears (R)

Question

I have a nested list (or list-of lists) containing all integers. Some of the nested lists have NA values randomly allocated from a certain position in the nested list. I need to remove all of the positions in the nested list after the first NA appears.

For one example, in my sample data below of a list of 5 nested lists, L.miss, position L.miss[[2]] is a list of nine vectors of integers of varying length. The first NA appears on position L.miss[[2]][[4]][3] so any(is.na(L.miss[[2]][[4]])) returns TRUE. In my desired output, positions L.miss[[2]][4:9] need to be removed. The list L.want is the desired outcome.

L.miss <- list(list(1,3,c(0,2,0),c(NA)),
             list(1,6,c(0,3,2,0,1,0),c(0,0,NA,1,0,0),1,2,c(NA,1),2,c(0,0)),
             list(1,0),
             list(1,0),
             list(1,4,c(2,0,0,0),c(4,1),c(1,NA,0,0,0),0),
             list(1,0))

L.want <- list(list(1,3,c(0,2,0)),
             list(1,6,c(0,3,2,0,1,0)),
             list(1,0),
             list(1,0),
             list(1,4,c(2,0,0,0),c(4,1),
             list(1,0))

My attempt was to iterate through the list positions and assign a NULL value:

try <- L.miss 
for (i in 1:length(try)){
  for (k in 1:length(try[[i]])){
    if (any(is.na(try[[i]][[k]]))){
      try[[i]][k:length(try[[i]])] <- NULL
    }
  }
}

But this returns the error: Error in try1[[i]][[k]] : subscript out of bounds.

I am assuming this is because it initiates the k for loop at the full length of the nested list, then removes an element so now goes out of bounds, but I don't know of any alternatives to this solution despite an exhaustive search.

Any advice is appreciated!

Answer 1

Here's a way :

out_list <- lapply(L.miss, function(x) {
               inds <- sapply(x, function(x) any(is.na(x)))
               if(any(inds)) x[seq_len(which.max(inds) - 1)] else x
             })

out_list[[2]]
#[[1]]
#[1] 1

#[[2]]
#[1] 6

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