[R] Adding elements in an array where I have missing data.

[Rick Bilonick]

On Mon, 2006-05-01 at 13:26 -0400, John Kane wrote:
> This is a simple question but I cannot seem to find
> the answer.
> I have two vectors but with missing data and I want to
> add them together with
> the NA's being ignored.
> 
> Clearly I need to get the NA ignored.  na.action?
> 
> I have done some searching and cannot get na.action to
> help.
> This must be a common enough issue that the answer is
> staring me in the face
> but I just don't see it.
> 
> Simple example
> a <- c(2, NA, 3)
> b <- c(3,4, 5)
> 
> What I want is
> c <- a + b where
> c  is ( 5 , 4 ,8)
> 
> However I get
> c is (5,NA, 8)
> 
> What am I missing?  Or do I somehow need to recode the
> NA's as missing?  
> 
> Thanks

Your example shows that you are not ignoring the NA's but treating them
as zeroes. This may or may not make sense depending on the application.

Your comment "Or do I somehow need to recode the NA's as missing" is
puzzling. NA denotes a missing value.

If you insist on treating NA's as zeroes, then just replace the NA's
with zeroes before adding:

> a[is.na(a)] <- 0

Rick B.


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