Differences between vectors _including_ NA

Question

Suppose I have a vector x<-c(1,2,NA,4,5,NA).

I apply some mythological code to that vector, which results in another vector, y<-c(1,NA,3, 4,10,NA)

Now I wish to find out at which positions my two vectors differ, where I count two NAs as being the same, and one NA and a non-NA (e.g. the second element of the two example vectors).

Specifically, for my example, I would like to end up with a vector holding c(2,3,5).

For my use case, I am not content with a vector of logical variables, but obviously I can easily convert (which), so I'll accept that as well.

I have some solutions like:

simplediff<-x!=y
nadiff<-is.na(x)!=is.na(y)
which(simplediff | nadiff)

but it feels like I'm reinventing the wheel here. Any better options?

Answer 1

How about looping and using identical?

 !mapply(identical,x,y)
[1] FALSE  TRUE  TRUE FALSE  TRUE FALSE

And for positions:

seq_along(x)[!mapply(identical,x,y)]
[1] 2 3 5

or

which(!mapply(identical,x,y))
[1] 2 3 5