R help - Jun 2003 - Truncating y axis

Hi folks,

I want to have a y-axis using matplot where the y axis is truncated as
shown schematically below:

(msecs)

3000 |   x
     ~ 
     ~  
800  |        x
     |
     |             x 
     |
     ----|----|----|-----------------
         1    2    3  
          Position

The ~ is supposed to stand for a curved line showing a break. The issue is
that I want to plot the points shown by the x's, but if I plot a
continuous y axis then the confidence intervals about the points at
positions 2 and 3 are not clearly visible...

Can someone suggest how this might be done? I did study the manuals and
contributed manuals first, and searched the archives and FAQs, just
couldn't find any discussion of such a situation.

Thanks much in advance,

-- 
Shravan Vasishth                               Phone: +49 (681) 302 4504    
Computational Linguistics, Universit?t des Saarlandes, Postfach 15 11 50
D-66041 Saarbr?cken, Germany         http://www.coli.uni-sb.de/~vasishth

On Sat, 28 Jun 2003 14:03:27 +0200 (MEST)
Shravan Vasishth <vasishth at coli.uni-sb.de> wrote:
> Hi folks,
> 
> I want to have a y-axis using matplot where the y axis is truncated as
> shown schematically below:
> 
> (msecs)
> 
> 3000 |   x
>      ~ 
>      ~  
> 800  |        x
>      |
>      |             x 
>      |
>      ----|----|----|-----------------
>          1    2    3  
>           Position
> 
> The ~ is supposed to stand for a curved line showing a break. The issue is
> that I want to plot the points shown by the x's, but if I plot a
> continuous y axis then the confidence intervals about the points at
> positions 2 and 3 are not clearly visible...
> 
> Can someone suggest how this might be done? I did study the manuals and
> contributed manuals first, and searched the archives and FAQs, just
> couldn't find any discussion of such a situation.
> 
> Thanks much in advance,
> 
> -- 
> Shravan Vasishth                               Phone: +49 (681) 302 4504
See W. Cleveland "The Elements of Graphing Data" (Hobart Press) for
reasons not to do this.    Consider using a nonlinear scale or making the graph
taller.

---
Frank E Harrell Jr              Prof. of Biostatistics & Statistics
Div. of Biostatistics & Epidem. Dept. of Health Evaluation Sciences
U. Virginia School of Medicine  http://hesweb1.med.virginia.edu/biostat

> I want to have a y-axis using matplot where the y axis is truncated as
> shown schematically below:
One (not so elegant) way is this:

# original data with one very large y value
x <- c(1, 2, 3, 4, 5)
y <- c(1000, 120, 110, 108, 104)
plot(x,y)

# truncated y-axis plot
y <- c(140, 120, 110, 108, 104)
plot(x,y, yaxt="n")
axis(side=2, at=c(100, 105, 110, 115, 120, 140), labels=c(100, 105, 110, 115,
120, 1000))
rect(0, 130, 1, 131, col="white", border="white")
par(xpd=T)
lines(x=c(0.7,1), y=c(130, 130))
lines(x=c(0.7,1), y=c(131, 131))

--
Wolfgang Viechtbauer