[R] break error bars in ggplot2

[Ben Bolker]

Fischer, Felix <Felix.Fischer <at> charite.de> writes:

> 
> Hello,
> 
> i use ggplot to plot some measures including CIs as horizontal 
> errorbars. I get an error when the scale
> limits are narrower than the boundaries of the error bar and
>  hence the CIs are not plotted.
> 
> library(ggplot2)
> df <- data.frame(resp=c(1,2), k=c(1,2), se=c(1,2))
> 
> ggplot(df, aes(resp,y=k)) +  geom_point() + 
>   geom_errorbarh(aes(xmax = resp + se, xmin = resp - se)) +  
> scale_x_continuous(limits=c(-1,3))
> 
> Is there a way to plot the errorbars anyway? Setting 
> xmax to the scale limit is not so good, I guess, because
> you couldn't determine whether the CI is wider than the scale limits or not.

  I'm not sure I completely understand your last paragraph, but
I think you want to substitute

  coord_cartesian(xlim=c(-1,3))

for your scale_x_continuous() component; as discussed in the ggplot2
book, limits set on scales act differently than limits set on 
coordinate systems.  (I'm a little surprised you get an error, though.)

  There's a very active ggplot2 google group that might be best
for ggplot(2)-specific questions ...