Combine column to remove NA's

Question

I have some columns in R and for each row there will only ever be a value in one of them, the rest will be NA\'s. I want to combine these into one column with the non-NA val

Answer 1

If you want to stick with base,

data <- data.frame('a' = c('A','B','C','D','E'),'x' = c(1,2,NA,NA,NA),'y' = c(NA,NA,3,NA,NA),'z' = c(NA,NA,NA,4,5))
data[is.na(data)]<-","
data$mycol<-paste0(data$x,data$y,data$z)
data$mycol <- gsub(',','',data$mycol)

Answer 2

max works too. Also works on strings vectors.

cbind(data[1], mycol=apply(data[-1], 1, max, na.rm=T))

Answer 3

I would use rowSums() with the na.rm = TRUE argument:

cbind.data.frame(a=data$a, mycol = rowSums(data[, -1], na.rm = TRUE))

which gives:

> cbind.data.frame(a=data$a, mycol = rowSums(data[, -1], na.rm = TRUE))
  a mycol
1 A     1
2 B     2
3 C     3
4 D     4
5 E     5

You have to call the method directly (cbind.data.frame) as the first argument above is not a data frame.

Answer 4

One possibility using dplyr and tidyr could be:

data %>%
 gather(variables, mycol, -1, na.rm = TRUE) %>%
 select(-variables)

   a mycol
1  A     1
2  B     2
8  C     3
14 D     4
15 E     5

Here it transforms the data from wide to long format, excluding the first column from this operation and removing the NAs.