On Jun 22, 2009, at 6:19 PM, Mark Na wrote:
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$Mean2<-apply(datac,2,mean)
Error in dimnames(x) <- dn :
length of 'dimnames' [2] not equal to array extent
If you are trying to create a group means value for each element in an
array or data.frame then the function to use is ave with its default
function is mean. Other functions can be used but that is not
necessary here. You could try:
datac$Mean2<-apply(datac,2,ave)
Can anyone see what I'm doing wrong?
Thanks!
Mark Na
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
