Replace blank cells with character

Question

I'm working on a data set that looks as follow:

191  
282 A

202  
210 B

I would like to replace those empty cells at the second column with a character, say 'N'. How can I efficiently do this in R?

Appreciate it.

Answer 1

An example data frame:

dat <- read.table(text = "
191 ''
282 A
202 ''
210 B")

You can use sub to replace the empty strings with "N":

dat$V2 <- sub("^$", "N", dat$V2)

#    V1 V2
# 1 191  N
# 2 282  A
# 3 202  N
# 4 210  B

Answer 2

Another way:

Assuming the same data structure as wibeasley has put:

ds <- data.frame(ID=c(191, 282, 202, 210), Group=c("", "A", "", "B"), stringsAsFactors=FALSE)

you can just write:

ds$Group[ds$Group==""]<-"N"