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
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