# [R] how to fill between 2 stair plots

Peter Dalgaard P.Dalgaard at biostat.ku.dk
Mon Feb 26 09:41:48 CET 2007

```Williams Scott wrote:
> Hi all,
>
> I want to create a simple plot with 2 type='s' lines on it:
>
> plot(a, b, type='s')
> lines(x, y, type='s')
>
> I wish to then fill the area between the curves with a colour to
> accentuate the differences eg col=gray(0.95). I cant seem to come up
> with a simple method for this. Any pointers in the right direction much
> appreciated.
>
>
I don't think there is a really simple method for this. I'd start with
converting the two 's' lines to ordinary lines along the lines of

N <- length(a)
a1 <- c(a[1],rep(a[-1],each=2),a[N]) # possibly a[N]+a_bit for the final
step)
b1 <- rep(b,each=2)

x1, y1 similarly, then

polygon(c(a1,rev(x1)),c(b1,rev(y1), col="grey")

(Did I confuse 's' and 'S'? Anyways, you get the idea)

> Cheers
>
> Scott
> _____________________________
>
> Dr. Scott Williams
>
> MBBS BScMed FRANZCR
>
> Peter MacCallum Cancer Centre
>
> Melbourne, Australia
>
> scott.williams at petermac.org
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> and provide commented, minimal, self-contained, reproducible code.
>

--
O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907

```