[R] Follow up: surfaces and digital terrain model
andrew.niccolai at yale.edu
Thu May 31 22:54:17 CEST 2007
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.
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,
Dr Renaud Lancelot, v?t?rinaire
CIRAD, D?partement Elevage et M?decine V?t?rinaire (CIRAD-Emvt)
Programme Productions Animales
ISRA-LNERV tel +221 832 49 02
BP 2057 Dakar-Hann fax +221 821 18 79 (CIRAD)
Senegal e-mail renaud.lancelot_at_cirad.fr
More information about the R-help