CODEWITHSUNDEEP
rmerge
Inno
Inno

Reputation: 75

How to merge two lists in parallel in R?

I'm asking to how to merge two lists in parallel, not orderly append as below codes.

For example,

A <- list(c(1,2,3), c(3,4,5), c(6,7,8))

B <- list(c("a", "b", "c"), c("d", "e", "f"), c("g", "h", "i"))

As results,

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

[[1]][[2]]
[1] "a" "b" "c"


[[2]]
[[2]][[1]]
[1] 3 4 5

[[2]][[2]]
[1] "d" "e" "f"


[[3]]
[[3]][[1]]
[1] 6 7 8

[[3]][[2]]
[1] "g" "h" "i"

Upvotes: 2

Views: 2643

Answers (2)

S.C
S.C

Reputation: 740

A longer approach (not recursive yet, up to second level merging):

A <- list(c(1,2,3), c(3,4,5), c(6,7,8))

B <- list(c("a", "b", "c"), c("d", "e", "f"), c("g", "h", "i"))

mergepar <- function(x = A, y = B) { # merge two lists in parallel
    ln <- max(length(x), length(y)) # max length
    newlist <- as.list(rep(NA, ln)) # empty list of max length

    for (i in 1:ln) { # for1, across length
        # two level subsetting (first with [ and then [[, so no subscript out of bound error) and lapply
        newlist[[i]] <- lapply(list(A, B), function(x) "[["("["(x, i), 1)) 
    }

    return(newlist)
}

Upvotes: 0

agstudy
agstudy

Reputation: 121578

Using  Map simply:

   Map(list,A,B)

Upvotes: 7

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