R help - Oct 2006 - qplot of ggplot package how to plot different size according to the values and not to the weights?

I have the following Data structure

$ step45     : Factor w/ 2 levels
$ obserror   : num  6.2 6.2 5.6 6.6 6.6 ...
$ Mon        : num  2.2 2.0 1.0 3.2 2.0 ...
$ inc.comp   : num  4 5 2 5 5 5 5 5 4 4 ...

all I wanted to do is plotting Mon against obserror, the colors should
be by step45 and the size of the symbol should be according to inc.comp
so I did this:

qplot(obserror,Mon,data=obscomp,col=inc.comp,col=step45)

unfortunately the size of the is something I do not want it to be, the
legend for inc.comp says: 4, 2.25, 1 ,0.25 , 0 I suppose this are weights?

I got closer to what I want specify a different symbol instead of a
different size:

qplot(obserror,Mon,data=obscomp,shape=as.factor(inc.comp),col=step45)

I needed the as.factor otherwise the plot is again different. But that
did not work with size. OK I thought this is a second best solution but
unfortunately the symbols are to small. But setting a size = 3 which I
thout adds a constant size everywhere (somehow expectedly) did add a
third legend "3" with 3.61, 3.42, ...

(The color worked fine)

Unfortunately the documentation of qplot is rather short ("FIXME")...

So is there a kind of option to use for the size just the values and not
the weights? Or a possibility to switch of "3" for legend plotting?

Another thing what I like to complain about is that qplot is using only
half of the windows graphics device space (especially wen adding this
size =3) which is not only ugly but a waste of space...

Stefan

R-2.4.0
Windows XP Prof.

On 10/27/06, Stefan Grosse <singularitaet at gmx.net>
wrote:
> I have the following Data structure
>
> $ step45     : Factor w/ 2 levels
> $ obserror   : num  6.2 6.2 5.6 6.6 6.6 ...
> $ Mon        : num  2.2 2.0 1.0 3.2 2.0 ...
> $ inc.comp   : num  4 5 2 5 5 5 5 5 4 4 ...
>
> all I wanted to do is plotting Mon against obserror, the colors should
> be by step45 and the size of the symbol should be according to inc.comp
> so I did this:
>
> qplot(obserror,Mon,data=obscomp,col=inc.comp,col=step45)
I think you mean
> qplot(obserror,Mon,data=obscomp, size=inc.comp,col=step45)
> unfortunately the size of the is something I do not want it to be, the
> legend for inc.comp says: 4, 2.25, 1 ,0.25 , 0 I suppose this are weights?
I think there are two things here that are confusing you (both my fault)

 * the size aesthetic actually modifies the area (ie. sqrt(size)) of
the points, because that is better perceptually

 * the legend isn't very good

But it is mapping the inc.comp to the size of the variable.

> I needed the as.factor otherwise the plot is again different. But that
> did not work with size. OK I thought this is a second best solution but
> unfortunately the symbols are to small. But setting a size = 3 which I
> thout adds a constant size everywhere (somehow expectedly) did add a
> third legend "3" with 3.61, 3.42, ...
qplot currently doesn't have any way to set an aesthetic to a fixed
value (it can't tell that you're specifying an aesthetic value not a
data value).  You can do this in two steps though

p <- qplot(wt, mpg, data=mtcars, type=NULL, shape=cyl)
ggpoint(p, size=3)
> Another thing what I like to complain about is that qplot is using only
> half of the windows graphics device space (especially wen adding this
> size =3) which is not only ugly but a waste of space...
That sounds like a bug.  Could you please provide a reproducible example?

Thanks,

Hadley

here an example with the car data
qplot(drat,wt,data=mtcars,shape=as.factor(carb),col=am,size=3)

it gets a bit better if one takes away the as.factor (but that of course
changes other things)

The picture is saved via metafile, screenshot did not work (mostly black
whyever) I know its deleted for the list...


Stefan
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