A + B with NA in r

Question

I want to calculate A+B in r

A <- c(NA,2,3,4,5)
B <- c(1,2,3,4,NA)

The ideal output is:

(1,4,6,8,5)

Is there a way to achieve this without replacing NA with 0? Thanks.

https://stackoverflow.com/questions/13123638/there-is-pmin-and-pmax-each-taking-na-rm-why-no-psum — rawr, Mar 09 '20 at 15:36
Out of curiosity, what would be your expected output for A*B and A/B? — asachet, Mar 09 '20 at 15:36
Sorry, I made a bad example here. I just wanted to say that I need to get the mean or sum or some other analysis out of many datasets, so replacing the NA with 0 may introduce bias at some time. — Jeremy, Mar 09 '20 at 15:44

score 2 · Answer 1 · edited Mar 09 '20 at 15:48

2

you can do it with rowSums:

rowSums(data.frame(A,B), na.rm=TRUE)

edited Mar 09 '20 at 15:48

Darren Tsai

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answered Mar 09 '20 at 15:38

Armando González Díaz

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score 2 · Accepted Answer · answered Mar 09 '20 at 15:50

2

You can always implement your own sum:

mysum <- function(...) {
  plus <- function(x, y) {
    ifelse(is.na(x), 0, x) + ifelse(is.na(y), 0, y)
  }
  Reduce(plus, list(...))
}

A <- c(NA,2,3,4,5)
B <- c(1,2,3,4,NA)

mysum(A, B)
#> [1] 1 4 6 8 5
mysum(A, A)
#> [1]  0  4  6  8 10
mysum(A, B, A, B)
#> [1]  2  8 12 16 10

^{Created on 2020-03-09 by the reprex package (v0.3.0)}

answered Mar 09 '20 at 15:50

asachet

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@Jeremy what do you mean by a matrix? This would definitely not work for a matrix – rawr Mar 09 '20 at 16:20
@rawr Sure it does: `A <- matrix(1:9, nrow = 3) ; B <- matrix(c(NA, 2:8, NA), nrow = 3) ; mysum(A, B)` – asachet Mar 09 '20 at 16:54
@asac op wants a vector, yes? – rawr Mar 09 '20 at 17:17

A + B with NA in r

2 Answers2