ignore NA in dplyr row sum

Question

is there an elegant way to handle NA as 0 (na.rm = TRUE) in dplyr?

data <- data.frame(a=c(1,2,3,4), b=c(4,NA,5,6), c=c(7,8,9,NA))  data %>% mutate(sum = a + b + c)  a  b  c sum 1  4  7  12 2 NA  8  NA 3  5  9  17 4  6 NA  NA 

but I like to get

a  b  c sum 1  4  7  12 2 NA  8  10 3  5  9  17 4  6 NA  10 

even if I know that this is not the desired result in many other cases

Answer 1

You could use this:

library(dplyr) data %>%    #rowwise will make sure the sum operation will occur on each row   rowwise() %>%    #then a simple sum(..., na.rm=TRUE) is enough to result in what you need   mutate(sum = sum(a,b,c, na.rm=TRUE)) 

Output:

Source: local data frame [4 x 4] Groups: <by row>        a     b     c   sum   (dbl) (dbl) (dbl) (dbl) 1     1     4     7    12 2     2    NA     8    10 3     3     5     9    17 4     4     6    NA    10