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

[John Kane]

--- John Fox <jfox at mcmaster.ca> wrote:

> Dear John,
> 
> The behaviour of R is reasonable, since, in your
> example, 4 + NA should in
> general be NA (i.e., missing). You can do what you
> want by changing NAs to
> 0s:
> 
> > a[is.na(a)] <- 0
> > a + b
> [1] 5 4 8
> 
> I hope this helps,
>  John

Thanks John.  Just what I needed. 
I realised that R was being reasonable, I  just did
not how to easily get around it. I was using sum(x
na.rm=T) and I guess I was looking for something
similar.


> 
> --------------------------------
> John Fox
> Department of Sociology
> McMaster University
> Hamilton, Ontario
> Canada L8S 4M4
> 905-525-9140x23604
> http://socserv.mcmaster.ca/jfox 
> -------------------------------- 
> 
> > -----Original Message-----
> > From: r-help-bounces at stat.math.ethz.ch 
> > [mailto:r-help-bounces at stat.math.ethz.ch] On
> Behalf Of John Kane
> > Sent: Monday, May 01, 2006 12:26 PM
> > To: R R-help
> > Subject: [R] Adding elements in an array where I
> have missing data.
> > 
> > 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
> > 
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