[GRASS-stats] hypsometric integral from ecdf curve

[Roger Bivand]

On Wed, 28 Jan 2009, pierluigi de rosa wrote:

> Dear All,
>
> I need to evaluate an Hypsometric integral but i should "rotate" the
> graphical output of
>
> plot(ecdf(elev$elev))
>
> I want in x the fraction of observations (pixel value of elevation) that
> are above the elevation in y
>
> the  command: plot(ecdf(elev$elev)) show in x the elevation and in y the
> fraction of observation that are below the value of elevation in x
>
> The value of 1 in plot(ecdf(elev$elev)) correspond to the maximum value
> of elevation. I want the it correspond to the value of minimum.

It looks as though:

res <- plot.stepfun(ecdf(elev$elev))
plot(res$y[-1], res$t[-c(1, length(res$t))], xlim=c(1, 0), type="l", 
ylab="elev", xlab="F(x)")

gets you there. I can't see an argument in the first step to turn plotting 
off.

Best wishes,

Roger

>
> thanks
>
> Pierluigi
>

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no