[R] ggplot: dodge positions

[Thaler,Thorn,LAUSANNE,Applied Mathematics]

I guess it works with ggplot but not with ggplot2. I'm using only the latter but had a typo in my first post. So the code (which does not do what I want) is:

library(ggplot2)
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()

Thinking of it, I would need to find out which offset ggplot uses to dodge the nested factors. If I knew the exact quantity, I could do something like

geom_point(aes(x = offset.used.by.geom_boxplot))

So how are the exact positions on the x-axis for geom_boxplot determined? Any ideas?

Thanks for the help, anyways.

KR,

-Thorn


> -----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,
> > Nestlé Research Center
> > PO Box 44
> > CH-1000 Lausanne 26
> > Phone: +41 21 785 8220
> > Fax: +41 21 785 9486
> 
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