CODEWITHSUNDEEP
rlistvector
user3755880
user3755880

Reputation: 375

R: list of vectors - grouping identical vectors together

I have a list of numeric vectors. Some of these vectors are identical, and so what I want to do is find a simple and quick way to group the identical vectors together and create a list for each of the groups of identical vectors, and potentially save all of the lists we just created into a single giant list. Any help would be appreciated!

Upvotes: 2

Views: 350

Answers (1)

Frank
Frank

Reputation: 66819

Here's an example:

x  <- list(v1= 1:3, v2 = 2:3, v3 = 2:3, v4 = 1:3, v5 = 4)

You can assign each element of the list a "group ID" using match and unique:

ux  <- unique(x)
# str(ux)
# List of 3
#  $ : int [1:3] 1 2 3
#  $ : int [1:2] 2 3
#  $ : num 4

gid <- match(x,ux)
# [1] 1 2 2 1 3

The gid corresponds to an element of ux.

Whatever you want to do from there is pretty straightforward, like ave(x, gid, FUN=some_function).

Upvotes: 2

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