[R] Isocontour-lines of spatial data on a rectangular grid (not plots!)

[Roger Bivand]

On Mon, 16 Jun 2003, Dieter Menne wrote:

> Dear R-Listers,
> 
> I have spatial data on an equidistant rectangular grid, similar to
> topographic data. I know that there are quite a few R-packages or base
> functions that provide nice iso-contours plot, but I don't want a plot, just
> the smoothed isocontour line of ONE level (e.g. 10 mm).
> 
> Data sets are large, so it would be preferable if the availability of
> regular grid data could be exploited, and the fact that I only need ONE
> isocontour line.  Polynomial fits are not adequate, but loess works nicely
> for the plots. Akima/interp might be a little too general, and if I remember
> Brian Ripley's comments correctly, the coefficients are "only for internal
> use".
> 
> Can someone suggest me a package?
> 
A similar question:

https://www.stat.math.ethz.ch/pipermail/r-help/2003-May/032907.html

was asked by Renaud Lancelot in late May. The source package for clines is 
at:

http://www.stat.auckland.ac.nz/~paul/R/clines_1.0.tar.gz

which returns chosen contours from an input matrix as used in contour().

Roger

> 
> Dieter Menne
> 
> ______________________________________________
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> 

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no