Loop a list to the N element

Question

Say i want to loop a list to the 10th element of said list. Can you tell me why code doesn't work?

loop <- function (list) {
  for (i in (list:list[[10]])) {
    df_i <- import(paste0(i))
  }
}
loop(list)

It returns:

Error in ord_dirs:ord_dirs[[10]] : NA/NaN argument
In addition: Warning messages:
1: In ord_dirs:ord_dirs[[10]] :
  numerical expression has 18 elements: only the first used
2: In pasardir(ord_dirs) : NAs introduced by coercion
3: In pasardir(ord_dirs) : NAs introduced by coercion

The `list:list[[10]]` should be `for i in in 1:10) {list[[i]]}` — akrun, Apr 08 '21 at 18:35
Also, the `i` in the name `df_i` won't change as `i` changes, just like if I have a variable named `data` and I set `a <- "hello"`, it doesn't become `dhellothello`. You should probably put your results in a `list`. Perhaps `df_list <- lapply(list[1:10], import)`... but it's hard to tell. Is `list` actually of class `list`, or is it a character vector of filepaths, or something else? — Gregor Thomas, Apr 08 '21 at 18:38
I'd suggest reading my answer at [How do I make a list of data frames?](https://stackoverflow.com/questions/17499013/how-do-i-make-a-list-of-data-frames/24376207#24376207) for discussion and examples. — Gregor Thomas, Apr 08 '21 at 18:38

score 0 · Answer 1 · answered Apr 09 '21 at 01:29

0

loop <- function(list, x = 10) {

  df <- as.list(rep(NA, x))

  for (i in 1:x) {
    df[i] <- list[i]
  }

  df

}

list <- letters

loop(list)

answered Apr 09 '21 at 01:29

Paul

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This looks like a verbose way to do `df <- list[1:10]`... I don't think that's what OP's goal is. – Gregor Thomas Apr 09 '21 at 01:46
Indeed, but `list[i]` can be replaced with `import` or whatever function is needed to achieve their goal. – Paul Apr 09 '21 at 02:38

Loop a list to the N element

1 Answers1