R help - Apr 2008 - How to access the attributes of a ggplot?

Hi,

I am having some hard time figuring how to access (and modify) the
properties of an object created by ggplot.

I found 'ggopts', but it only returns some of the properties.  Say I
want to get the x- and y-axis limits, the tickmark locations, legend
current position, the legend box and background color and set them to
new values.

Are these properties easily accessible (and modifiable) from the object?

Here is an example

library(ggplot2)
pobj <- ggplot(data = movies[1:300,], aes(x = year, y = length, size rating))
+ geom_point() + opts(legend.position = c(0.2,0.9))

Regards,

TL

Hi Tribo,
>  I found 'ggopts', but it only returns some of the properties.  Say
I
>  want to get the x- and y-axis limits, the tickmark locations, legend
>  current position, the legend box and background color and set them to
>  new values.
>
>  Are these properties easily accessible (and modifiable) from the object?
Some of them are:

 * the x and y axis limits are properties of the scales (e.g. +
scale_x_continuous(limits=c(5, 10))
 * the tickmark locations and labels are also properties of the scales
(e.g. + scale_x_continuous(breaks=c(5, 10),
labels=c("five","ten"))
 * the legend position is set by ggopt()

Some of them aren't:

 * legend fill and outline colours can only be changed by modifying
the underlying grid object - see the last chapter of the ggplot book
to see how to do this.

Hadley


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