I have two large lists with 1000 elements each, for example:

list.A
$ V1    : num [1:141089] 1 2 3 4 5 ...
$ V2    : num [1:141089] 2 1 4 3 6 ...
$ ..
$ V1000 : num [1:141089] 5 6 7 8 9 ...


list.B
$ V1    : num [1:141089] 5 4 3 2 1 ...
$ V2    : num [1:141089] 4 5 2 3 0 ...
$ ..
$ V1000 : num [1:141089] 9 8 7 6 5 ...

see list.A example figure

I would like to perform operations for n^th vector in one list by all vector in the second list. For instance: V1 in list.A against V1 in list.B, V2 in list.B, until V1000 in list.B. And the same for V2 until V1000 in list.A.

So far, here is how my code looks like.

list.diff <- Map(function(num1, num2) sum(abs(num1 - num2)/20)/(141089), list.A, list.B)

By using Map in R, I can only perform operations for n^th vector in one list by the n^th vector in the second list. For instance, V1 in list.A against V1 in list.B, and then V2 in list.A against V2 in list.B.

Any suggestions how to solve this? I am new to R and stackoverflow. Many thanks for taking the time to answer.

CodePudding user response：

You could use nested lapply() and sapply() calls:

set.seed(13)

list.A <- setNames(
  replicate(3, sample(0:9, 3, replace = TRUE), simplify = FALSE),
  paste0("V", 1:3)
)

list.B <- setNames(
  replicate(3, sample(0:9, 3, replace = TRUE), simplify = FALSE),
  paste0("V", 1:3)
)

list.diff <- lapply(
  list.A, 
  \(num1) sapply(list.B, \(num2) mean(abs(num1 - num2)/20))
)

list.diff

$V1
       V1        V2        V3 
0.2666667 0.1166667 0.1833333 

$V2
       V1        V2        V3 
0.2333333 0.1500000 0.1833333 

$V3
        V1         V2         V3 
0.15000000 0.13333333 0.06666667 

Note, I also simplified sum(...)/141089 to mean(...).