Converting NAs does not work in R

Question

I have a data frame, df, and a factor class vector, "EMAIL_STATUS". if I do:

table(df$EMAIL_STATUS, useNA="always")

I get 38716 <NA>, 638 "YES", 110 "9999".

I want to convert the 38716 s to "UNKNOWN". I try the following code:

df$EMAIL_STATUS[is.na(df$EMAIL_STATUS)] <- "UNKNOWN"

I get no error, but it does not convert the NAs to "UNKNOWN", in fact it does nothing.

Answer 1

This short example illustrates one of possible ways of introducing a new level into a factor:

x <- factor(c(NA, NA, "a", "b", NA, "b"))
x[is.na(x)] <- "c" # this won't work, no such level as "c" in levels(x)
## Warning message:
## In `[<-.factor`(`*tmp*`, is.na(x), value = "c") :
##   invalid factor level, NA generated
levels(x) <- c(levels(x), "c") #include a new category
x[is.na(x)] <- "c"
x
## [1] c c a b c b

Answer 2

Hard to say without example data but try this

df$EMAIL_STATUS <- as.character(df$EMAIL_STATUS)   
df[ df$EMAIL_STATUS %in% NA, "EMAIL_STATUS" ] <- "UNKNOWN"