[R] tapply

[rohan sadler]

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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