[R-sig-Geo] [R] Follow up: surfaces and digital terrain model

[Prof Brian Ripley]

I believe you are looking for the function contourLines() in package 
graphics.

At some point in the intervening years there was a clines package on CRAN, 
and if you know that you can find it at 
http://cran.r-project.org/src/contrib/Archive/C/clines_2.0-2.tar.gz
That confirms it has been superseded by contourLines.

BTW, it is Paul Murrell (two l's) we have to thank for this.


On Thu, 31 May 2007, Andrew Niccolai wrote:

> I realize that as of yesterday, this message thread is 4 years old but can
> someone possibly post the clines function that Renaud mentions in the
> posting below?  That would be wonderful and most appreciated.
>
> Thanks,
> Andrew
>
>
> Andrew Niccolai
> Doctoral Candidate
> Yale School of Forestry
>
>
>
> From: Renaud Lancelot <lancelot>
> Date: Fri May 30 22:37:02 2003
>
> Yesterday, I posted the following:
>
>>> I have computed a digital terrain model from a set of points (x, y, z)
>>> using the function interp() in package akima. I want to predict flooded
>>> surfaces given target values of z. I can display the flooded surfaces
>>> with contour() or image(), but I don't know how to get the polygons
>>> delimiting the surfaces. Did anyone write a function for this purpose ?
>
> Many thanks to Roger Bivand, Paul Murrel, Deepayan Sarkar, Barry
> Rowlingson and Thomas W Blackwell for their replies and their help. Paul
> Murrel provided me with a function "clines", kindly ported to Windows by
> Duncan Murdoch. This function does exactly what I need, i.e. it returns
> a list of polygons corresponding to target value(s) of z.
>
> I wrote a function to compute (hopefully !) what I want, i.e. predicted
> flooded surfaces given target values of z (managing the cases of several
> independent watered surfaces, possibly with islands). Provided that Paul
> Murrel agrees to share his function, I will be happy to send it to
> anyone wishing to use and improve it (and debug it ;-) ).
>
> Best regards and thanks again,
>
> Renaud
>
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595