[R] hello! i need help for a specific graphic issue

[hadley wickham]

On Wed, Mar 12, 2008 at 5:37 AM, Giacomo Prodi <bonoricus at yahoo.it> wrote:
> hello, ladyes and gentlemans.
>
>  check this:
>
>  means<-c(4,6,8)
>  stand.error<-c(0.1,0.3,0.5)
>
>  now i've strongly tryed to scatterplot the
>  means(y-axis),by showing their sd with the
>  arrow(..,code=3,angle=90) function.
>  The problem is that my x-axis has categorical values
>  (say, factor(x)), and the arrows() can't recognize
>  them as right coordinates.
>  ?????
>  thank you all in advance
>  B.F. insubria university (varese)

This is a bit easier to do with ggplot2:

df <- data.frame(
  trt = factor(c("a", "b", "c")),
  mean = c(4,6,8),
  se = c(0.1,0.3,0.5)
)

install.packages("ggplot2")
library(ggplot2)

qplot(trt, mean, data=df)
qplot(trt, mean, data=df, min=mean - se, max = mean + se, geom="pointrange")

Hadley

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