I don't understant what you're doing with the means calculation. Howvever if you want the standard errors ( your se function) then will this do what you want?
df <- data.frame(x=c(1:10),y=sin(1:10),z=cos(1:10)); df dfm<-melt(df, id=c("x"), measured=c("y","z")); dfm se <- function(x) sd(x)/sqrt(length(x)) sse <- cast(dfm, variable~., se) I haven't used ggplot enough to be able to help there. --- baptiste Augui� <[EMAIL PROTECTED]> wrote: > Hi, > > I've been trying to do the following simple thing: > given a data.frame, > > > library(reshape) > > library(ggplot2) > > > > df <- > data.frame(x=c(1:10),y=sin(1:10),z=cos(1:10)) > > dfm<-melt(df, id=c("x"), measured=c("y","z")) > > > i want to plot y and z against x, and add vertical > errorbars to the > points corresponding to the standard deviation of y > and z respectively. > > I tried the following, inspired by some previous > post in the list, > > > se <- function(x) sd(x)/sqrt(length(x)) > > means <- cast(dfm, variable~., function(x) c(se = > se(x))) > > > > qplot(value,x, data=means, colour=variable, min = > value - se, max = > > value + se, geom=c("point","errorbar")) > > > but this fails, as I obviously don't get the > philosophy behind the > "cast" function. > > Any advice welcome! > > Thanks, > > baptiste > > _____________________________ > > Baptiste Augui� > > Physics Department > University of Exeter > Stocker Road, > Exeter, Devon, > EX4 4QL, UK > > Phone: +44 1392 264187 > > http://newton.ex.ac.uk/research/emag > http://projects.ex.ac.uk/atto > > ______________________________________________ > 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. > ______________________________________________ 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.