How do I replace NA values with zeros in an R dataframe?

Question

I have a data frame and some columns have NA values.

How do I replace these NA values with zeroes?

Answer 1

If we are trying to replace NAs when exporting, for example when writing to csv, then we can use:

  write.csv(data, "data.csv", na = "0")

Answer 2

If you want to replace NAs in factor variables, this might be useful:

n <- length(levels(data.vector))+1

data.vector <- as.numeric(data.vector)
data.vector[is.na(data.vector)] <- n
data.vector <- as.factor(data.vector)
levels(data.vector) <- c("level1","level2",...,"leveln", "NAlevel") 

It transforms a factor-vector into a numeric vector and adds another artifical numeric factor level, which is then transformed back to a factor-vector with one extra "NA-level" of your choice.