CODEWITHSUNDEEP
rlistjoinmerge
jul635
jul635

Reputation: 794

merging two lists in R (many-to-many relationship)

I am trying to merge 2 lists in R. The names of the list should be used to perform the join. Here is a toy example:

> list1 <- list(A=c(1,2,3), B=c(2,4,5,6), C=c(1,3))
> list2 <- list(A=c(w,x), B=c(y,z))

The final merged list should look like this:

$w
[1] 1 2 3
$x
[1] 1 2 3
$y
[1] 2 4 5 6
$z
[1] 2 4 5 6

The only idea I had so far was to convert the lists to data frames, and use the merge function. Is there anything simpler to do?

Thanks a lot for your help.

Upvotes: 0

Views: 1357

Answers (1)

AndrewMacDonald
AndrewMacDonald

Reputation: 2950

Hopefully this is something like what you want? In fact you don't need list2 at all. Because lists are actually vectors, we can use a named vector to "lookup" the values of list1 that we need, then assign those names to the new list

list1 <- list(A=c(1,2,3), B=c(2,4,5,6), C=c(1,3))

lookup <- c(w = "A",x = "A",y = "B",z = "B")

list2 <- list1[lookup]

names(list2) <- names(lookup)

list2
$w
[1] 1 2 3

$x
[1] 1 2 3

$y
[1] 2 4 5 6

$z
[1] 2 4 5 6

Upvotes: 5

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