[R] Median abline how-to ?

[Jim Lemon]

On 08/13/2010 12:41 AM, David martin wrote:
> Hi,
> I'm newbie with R and don't really know how to add a median line to each
> of the groups that is not all the plot long.
>
> Here is a small working code that i have adapted for my purpose. If
> somebody could tell me how to draw median lines on each group and not
> all plot long.
>
> ctl <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
> trt <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
> group <- gl(2,10,20, labels=c("Ctl","Trt"))
> weight <- c(ctl, trt)
>
> ctlmed <- median(weight[which(group == "Ctl")])
> trtmed <- median(weight[which(group == "Trt")])
> plot.default(weight ~ group,axes=F)
> axis(2,col.axis = "blue",las=1,cex.axis=0.7,xpd=TRUE)
> axis(1,
> labels=levels(group),at=1:length(unique(group)),las=2,cex.axis=0.7)
> #horizontal
> abline(h = ctlmed, col = "blue", lwd = 2) # ?? how to make abline shorter ?
> abline(h = trtmed, col = "red", lwd = 2)
> box(bty="c")
>
Hi David,
Look at ablineclip in the plotrix package.

Jim