[R] Calculating "row standard deviations"

Peter Alspach PAlspach at hortresearch.co.nz
Tue Jun 23 00:37:12 CEST 2009


Tena koe Mark

I think you might want

apply(datac, 1, mean) 

i.e., apply the function to the first dimension (rows) rather than the
second (columns).

HTH ...

Peter Alspach

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Mark Na
> Sent: Tuesday, 23 June 2009 10:20 a.m.
> To: r-help at r-project.org
> Subject: [R] Calculating "row standard deviations"
> 
> Hi R-helpers,
> 
> I have been struggling with calculating row and column 
> statistics, e.g. standard deviation.
> 
> I know that
> > datac$Mean<-rowMeans(datac,na.rm=TRUE)
> will give me row means.
> 
> I have tried to replicate those row means with the apply function:
> > datac$Mean2<-apply(datac,2,mean)
> 
> so that I can replace the function argument with "sd" (instead of
> mean) to get standard deviations.
> 
> But, I'm running into this error:
> 
> > dim(datac)
> [1]  17 271
> > datac$Mean2<-apply(datac,2,mean)
> Error in dimnames(x) <- dn :
>   length of 'dimnames' [2] not equal to array extent
> 
> 
> Can anyone see what I'm doing wrong?
> 
> Thanks!
> 
> Mark Na
> 
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