Hi Bryn,
You just need to use the na.rm=T option (look under help for the mean
function)
e.g.
> x<-c(1,4,6,NA,10,18) # data
> mean(x)
[1] NA
> mean(x,na.rm=T)
[1] 7.8
> y<-c(1,1,1,2,2,2) # factor variable
> tapply(x,y,mean)
1 2
3.666667 NA
> tapply(x,y,mean,na.rm=T)
1 2
3.666667 14.000000
Rohan
rbf21 wrote:
>I'm having trouble with tapply, it seems to give me NA for the mean of a
set
>like {2, 3, 4, NA}, can I get it to ignore the NA's and give me a mean
like
>say, three? Am I just doing something stupid?
>
>Any help would be apprecitated, Also are there PDF versions of any of the R
>stats books around that I might be able to get my hands on?
>
>Bryn
>
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>R-help at stat.math.ethz.ch mailing list
>http://www.stat.math.ethz.ch/mailman/listinfo/r-help
>
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