Brown, Heidi wrote:
Hi im trying to add error bars to my barplots, there very basic, i have a few
grapghs where the y variable is different but on all the X variable is Age
(Adult and Juvenile) however this is split into two levels so i have males and
females, so my graph basically has four bars on it.
I know how to add eror bars for instance when there is only one level eg lookng at the diffrence between male and female lizards and tree height and have used the code:
error.bars<-function(yv,z,nn) {
xv<-
barplot(yv,ylim=c(0,(max(yv)+max(z))),names=nn,ylab=deparse(substitute(yv)
))
g=(max(xv)-min(xv))/50
for (i in 1:length(xv)) {
lines(c(xv[i],xv[i]),c(yv[i]+z[i],yv[i]-z[i]))
lines(c(xv[i]-g,xv[i]+g),c(yv[i]+z[i], yv[i]+z[i]))
lines(c(xv[i]-g,xv[i]+g),c(yv[i]-z[i], yv[i]-z[i]))
}}
Have then worked out the standard errors and added that using:
se<-c()
and then added the final bit of code:
labels<-as.character(levels(Sex2))
ybar<-as.vector(tapply(Height2,Sex2,mean))
error.bars(ybar,se,labels)
So i was wondering, in order to get error bars on my barplot with two levels do
i need to change the last bit of code. For example im looking at mean body
condition (y) against age (x) and sex (level), i tried to change the code to
the following but it didnt work, any suggestions?
labels<-as.character(levels(list(sex,Age)))
ybar<-as.vector(tapply(ConditionIndex,sex,Age,mean))
error.bars(ybar,se,labels)
See http://biostat.mc.vanderbilt.edu/DynamitePlots for many reasons not
to use dynamite plots.
Frank
--
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University
______________________________________________
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.
