Problem with facet_grid in ggplot2
On 4/11/2011 9:33 AM, Simon Hayward wrote:
Hi all, I am practising a bit with ggplot2 but I have a problem when I try to use facet_grid. The following code:- p<- ggplot(diamonds, aes(carat, ..density..)) + + geom_histogram(binwidth = 1) p + facet_grid(cut ~ clarity, margins=TRUE) produce the following error:- Error in class(output[[var]])<- class(value) : cannot set class to "array" unless the dimension attribute has length
0
I have lifted this code directly from the ggplot2 documentation! By a process of elimination it seems that the problem arises from the use of margins. I do not know why the dimension attribute is conflicting with margins unless it is something to do with the properties of the data frame. I am running R 2.12.1 Has the source code changed? Very grateful for any help Simon Hayward
Simon, You have correctly figured out the problem; the margins argument does not work in facet_grid. It is a known bug. See, for example, http://groups.google.com/group/ggplot2/browse_thread/thread/8a49a200ac3172a7 http://groups.google.com/group/ggplot2/browse_thread/thread/97ba6e2f469792cc It is still there in ggplot2 0.8.9 (the latest release).
Brian S. Diggs, PhD Senior Research Associate, Department of Surgery Oregon Health & Science University