[R] ggplot: order of numeric factor levels?

hadley wickham h.wickham at gmail.com
Wed Apr 1 02:07:21 CEST 2009


On Tue, Mar 31, 2009 at 5:01 PM, Marianne Promberger
<mpromber at psych.upenn.edu> wrote:
> Hi,
>
> I'm having problems with qplot and the order of numeric factor levels.
>
> Factors with numeric levels show up in the order in which they appear
> in the data, not in the order of the levels (as far as I understand
> factors!)
>
> Here is a minimal example:
>
> library(ggplot2)
> y <- c(-1,2,0,0,-2,-1)
> z <- factor(y,levels=c(-2,-1,0,1,2))
> qplot(z)
>
> For me, the resulting plot is ordered: -1,2,0,-2
>
> By contrast,
> plot(z) is neatly ordered -2,-1,0,1,2
>
> What am I not getting?

It's a bug in the current version.  You can fix it by explicitly
setting the limits for the x axis - + xlim("-2","-1","0","1","2")).
It will be fixed in the next release which I'm trying to get out soon.

Hadley


-- 
http://had.co.nz/




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