Replace NAs in one variable with values from another variable

Question

How can I replace the \"NAs\" of a variable VAR1 with with the values of the second variable VAR2 to create a third variable VAR3 in R? The data looks like this:

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Answer 1

One easy way is to use pmax with na.rm = TRUE:

pmax(VAR1, VAR2, na.rm = TRUE)

The command for data frame dat:

dat <- transform(dat, VAR3 = pmax(VAR1, VAR2, na.rm = TRUE))