[R] ggplot / reshape: basic usage

[John Kane]

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� <ba208 at exeter.ac.uk> 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
> 
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