Question

Possible Duplicate:
Combining two vectors element-by-element

I have two vectors

d = c(1, 2, NA, NA)
c = c(NA, NA, 1, NA)

How can I get an output that would combine the non NAs as follows?

[1] 1 2  1 NA

thanks

Answer 1

What you are asking is a bit vague. For example, what happens if you neither element is a NA?

Anyway, here’s one method that gives the desired result:

##Don't name things c - it's confusing.
d1 = c(1,2,NA,NA)
d2 = c(NA,NA,1,NA)

d1[is.na(d1)] = d2[is.na(d1)]

Which gives:

R> d1
[1]  1  2  1 NA