ggplot: dodge positions

-----Original Message-----
From: John Kane [mailto:jrkrideau at inbox.com]
Sent: Montag, 2. Juli 2012 15:04
To: Thaler,Thorn,LAUSANNE,Applied Mathematics; r-help at r-project.org
Subject: RE: [R] ggplot: dodge positions

Can you expand a bit on what is wrong with the dodge option?  From what
I see it looks lovely witht the points exactly lined with the boxplots
for each group but perhaps I don't understand exactly what you want .



John Kane
Kingston ON Canada

-----Original Message-----
From: thorn.thaler at rdls.nestle.com
Sent: Mon, 2 Jul 2012 11:43:03 +0200
To: r-help at r-project.org
Subject: [R] ggplot: dodge positions

Dear all,

I want to get a series of boxplots (grouped by two factors) and I

want to

overlay the original observations and the following code does almost

what

I want:

library(ggplot)
ddf <- data.frame(x=factor(rep(LETTERS[1:4], each=30)), y =
runif(120,0,10), grp = factor(rep(rep(1:3, 10), 4)))
ggplot(ddf, aes(x, y, colour=grp)) + geom_boxplot() + geom_point()

Yet the position of the points and the position of the boxes on the
x-axis is not the same. I would like that the points are shifted
accordingly, such that they line up with the boxplots. I tried
position_dodge:

ggplot(ddf, aes(x, y, colour=grp)) + geom_boxplot() +
geom_point(aes(ymax=max(y)), position = position_dodge(width=.75))

but that did not really help, as all points are now dodged and I just
want to have a fixed offset for each subgroup of points such that the
boxplot and the points are aligned. Any ideas?


Kind Regards,

Thorn Thaler
Mathematician

Applied Mathematics
Nestec Ltd,
Nestl? Research Center
PO Box 44
CH-1000 Lausanne 26
Phone: +41 21 785 8220
Fax: +41 21 785 9486