Because of the way you've constructed the plot with qplot, you need to use:
myPlot + geom_point(
data=medians,
aes(x=med,shape=cut, y=0),
size=2.5,
)
Hadley
On Wed, Apr 7, 2010 at 5:11 AM, Johannes Graumann
<johannes_graumann at web.de> wrote:> Hi,
>
> Please consider the example below. How can I manage to overlay the points
> the way I want in the second case?
>
> Thanks, Joh
>
> library(ggplot2)
>
> # Modify data to match "real" case
> myDiamonds <- diamonds
> myDiamonds[["clarity"]] <-
as.character(myDiamonds[["clarity"]])
>
myDiamonds[myDiamonds[["clarity"]]=="I1","clarity"]
<- 1
>
myDiamonds[myDiamonds[["clarity"]]=="SI2","clarity"]
<- 2
>
myDiamonds[myDiamonds[["clarity"]]=="SI1","clarity"]
<- 3
>
myDiamonds[myDiamonds[["clarity"]]=="VS2","clarity"]
<- 4
>
myDiamonds[myDiamonds[["clarity"]]=="VS1","clarity"]
<- 5
>
myDiamonds[myDiamonds[["clarity"]]=="VVS2","clarity"]
<- 6
>
myDiamonds[myDiamonds[["clarity"]]=="VVS1","clarity"]
<- 7
>
myDiamonds[myDiamonds[["clarity"]]=="IF","clarity"]
<- 8
> myDiamonds[["clarity"]] <-
as.numeric(myDiamonds[["clarity"]])
>
> # Calculate medians
> medians <- ddply(
> ?myDiamonds,
> ?.(cut),
> ?summarize,
> ?med=median(clarity, na.rm=TRUE)
> )
>
> # Works
> myPlot <- qplot(
> ?factor(clarity),
> ?data=myDiamonds,
> ?fill=cut,
> ?geom="bar",
> ?position="dodge"
> )
>
> myPlot +
> geom_point(
> ?data=medians,
> ?aes(x=med,shape=cut),
> ?y=0,
> ?size=2.5,
> )
>
> # Doesn't work - I want density rather than count
> myPlot <-qplot(
> ?factor(clarity),
> ?y=..count../sum(..count..),
> ?data=myDiamonds,
> ?fill=cut,
> ?geom="bar",
> ?position="dodge"
> )
>
> myPlot +
> geom_point(
> ?data=medians,
> ?aes(x=med,shape=cut),
> ?y=0,
> ?size=2.5,
> )
>
> ______________________________________________
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
>
--
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/