Hi Brett,

have you tried the function "errbar", within the library "Hmisc"?
It works pretty well for barplots. You have to specify the coordinates where
error bars start ("x" and "y"), end then the ending points they end
("yminus=y-error" and "yplus=y+error").

The plotting function "barplot2" within the library "gplots" allows you also
to add error bars intrinsecally.

Hope it helps!

Jose

2009/12/3 bshan101 <bshan101@gmail.com>

>
> Hey Everyone,
>
> I'm pretty new at R and wanted to try and make some graphs with dummy data
> before using it to analyze my own. I successfully made a bar graph and
> error
> bars, but I can't figure out how to align them properly (currently they are
> not centered on the bars and some of them aren't even close). Here's the
> code that I'm using:
>
> > marks <- sample(4:10, size=50, replace=TRUE)
> > dim(marks) <- c(10,5)
> > classavg <- colMeans (marks, na.rm=FALSE, dims = 1)
> > barplot(classavg, main="Class Average for Quizzes", xlab="Quiz",
> > ylab="Average", names = c("1","2","3","4","5"), ylim=c(0,12), axis.lty=1)
> box()
> > max <- apply (marks, 2, max)
> > min <- apply (marks, 2, min)
> > arrows(1:5, min, 1:5, max, code=3, angle=90, length=0.125)
>
> The error bars are simply ranges for now (I wanted to do that before I
> tried
> standard deviation/error). If anyone could help me align them it would be
> much appreciated!
>
> brett
>
> --
> View this message in context:
> http://n4.nabble.com/Bar-Plots-Error-Bars-tp947407p947407.html
> Sent from the R help mailing list archive at Nabble.com.
>
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