[R] ylim in barplot2 function?

[Marc Schwartz]

On Wed, 2007-10-31 at 11:52 +0100, Dieter Vanderelst wrote:
> Hi list,
> 
> I'm using barplot2 form the gplots package to plot a few numbers (I
> want to add SD bars later).
> 
> However, I would like the y-axis not to start from 0 but 500. When I
> add the parameters YLIM, something goes wrong. The graph is not 'cut
> off' at 500. Instead the bars seems to sink trough the bottom of the
> graph.
> 
> Because its a little hard to explain, here is a self-containing
> example:
> 
> 
> library(gplots)
> 
> ABrt<-c(588,589,593,588)
> Wrt<-c(580,583,592,612)
> 
> RT<-rbind(ABrt,Wrt)
> barplot2(RT,beside=T,col=c('black','white'),ylim=c(500,1000))
> 
> Does anybody know of a solution?
> 
> Regards,
> Dieter

The behavior here is the same for both barplot() and barplot2(). You
need to set par("xpd") to FALSE, so that the bars are clipped to the
plot region:

barplot2(RT,beside=T,col=c('black','white'),ylim=c(500,1000), 
         xpd = FALSE)

See ?par

That being said, this is a bad idea in general, as you impact the
ability to visually discern the relative difference (or lack of it) in
the bars. You would be better off using a dotplot.

HTH,

Marc Schwartz