Another (also somewhat inelegant) way to do this might be as follows.
First write a small function to replace missing values by zeros:
zNA <- function(X) { X[is.na(X)] <- 0; X}
Now
testAve <- (zNA(test) + zNA(test2))/(2 - is.na(test) - is.na(test2))
If you are unlucky enough to have missing values at the same location in both
matrices, then this will give not NA but NaN in the average. If you really
want NA's in such places you need one more step:
is.na(testAve[is.nan(testAve)]) <- TRUE
(which may need a little decoding as well.)
________________________________________
From: [email protected] [[email protected]] On Behalf Of
Moshe Olshansky [[email protected]]
Sent: 14 July 2009 13:55
To: [email protected]; Tish Robertson
Subject: Re: [R] averaging two matrices whilst ignoring missing values
One (awkward) way to do this is:
x <- matrix(c(c(test),c(test2)),ncol=2)
y <- rowMeans(x,na.rm=TRUE)
testave <- matrix(y,nrow=nrow(test))
--- On Tue, 14/7/09, Tish Robertson <[email protected]> wrote:
> From: Tish Robertson <[email protected]>
> Subject: [R] averaging two matrices whilst ignoring missing values
> To: [email protected]
> Received: Tuesday, 14 July, 2009, 11:46 AM
>
> Hi folks,
>
>
>
> I'm trying to do something that seems like it should easy,
> but it apparently isn't. I have two large matrices,
> both containing a number of missing values at different
> cells. I would like to average these matrices, but the NAs
> are preventing me. I get a "non-numeric argument to binary
> operator" error. That's the first problem.
>
>
>
> test<-read.csv("test.csv",header=FALSE)
> test2<-read.csv("test2.csv",header=FALSE)
> test_ <- as.matrix(test,na.rm=T)
> test2_ <- as.matrix(test2,na.rm=T)
> testave<- (test_+test2_)/2
>
> ??
>
>
>
> So off the bat I'm doing something wrong.
>
>
>
> How would I replace the missing values in one matrix with
> the corresponding non-missing values in another? It's
> acceptable to me if I only have one value representing the
> average for a particular coordinate.
>
>
>
> Any help would be appreciated!
>
>
>
>
>
>
>
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
