CODEWITHSUNDEEP
rvectorsum
bud.dugong
bud.dugong

Reputation: 759

How to sum vector elements with the same name in R?

Most solutions I found were for data frames or lists, not for vectors.

From: myvec = c(A=2, B=2, A=2)

To: desiredvec = c(A=4, B=2)

Upvotes: 3

Views: 627

Answers (4)

ThomasIsCoding
ThomasIsCoding

Reputation: 101848

You can use tapply

> tapply(myvec, names(myvec), sum)
A B
4 2

or xtabs

> xtabs(myvec~names(myvec))
names(myvec)
A B
4 2

Upvotes: 5

akrun
akrun

Reputation: 887301

Using aggregate/stack

aggregate(values ~ ., stack(myvec), sum)

Upvotes: 0

Ronak Shah
Ronak Shah

Reputation: 389055

You can use rowsum :

rowsum(myvec, names(myvec))
#  [,1]
#A    4
#B    2

rowsum returns a matrix. If you need a vector.

rowsum(myvec, names(myvec))[, 1]
#A B 
#4 2

Upvotes: 1

bud.dugong
bud.dugong

Reputation: 759

Define:

splitbyitsnames <- function(namedVec) { # split a list by its names
  stopif(is.null(names(namedVec)), message = "NO NAMES")
  split(namedVec, f = names(namedVec))
}

unlapply <- function (...) { unlist(lapply(...)) } # lapply, then unlist

sumBySameName <- function(namedVec) { # Sum up vector elements with the same name
  unlapply(splitbyitsnames(namedVec), sum)
}

From CodeAndRoll

Call:

> sumBySameName(myvec)
A B 
4 2

Please add if there is a better solution

Upvotes: 0

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