From kohnicho@comp.nus.edu.sg  Thu Sep 28 07:08:51 2000
From: kohnicho@comp.nus.edu.sg (Nicholas Lewin-Koh)
Date: Thu, 28 Sep 2000 14:08:51 +0800 (GMT-8)
Subject: [Rd] New Web page -- Ideas list
In-Reply-To: <14802.18611.142952.540878@galadriel.ci.tuwien.ac.at>
Message-ID: <Pine.GSO.4.21.0009281340120.3143-100000@sununx.comp.nus.edu.sg>

Hi,
I was looking over the developer page of the new web site. In the ideas
section dynamic graphics and mapping are mentioned. I have a few comments
and wanted to get some feedback. 

Mapping: I am working on a package for mapping (I have sent notice to the
list). The ideas section of the web page mentions the Beckers/Wilks
code. I think ther model is very restrictive and perhaps a better system
could be implemented. I think there are two goals that the mapping
routines/data structures should address 1) display, and 2) analysis. On
the display end what I have noticed that could be improved: a) The display
when resized does not stay equally scaled, this is important for map
display. b) The polygon code does not deal well with multi-part polygons,
many gis and graphics systems allow holes, and islands, the polygon and
clipping routines can easily be adjusted to handle this. I can volunteer
to
do the polygon stuff, I have looked at the code in graphics.c and I think
I undestand what is going on. A zoom function on the device would be very
useful, especially if it would interact withhow the device is partioned by
the user, so that the first level of zoom would be to an individual
plot. These are the most immediate things that affect the R base code
directly.

Some other things that are more of a wishlist would be better color and
symbol facilities, I just finished writing an interactive color picker and
pallete selector using graphapp that works nicely from R. A tree node data
type that can be passed as a SEXP for making linked lists, binary trees
etc. I am writing an R+ tree as part of the map object and i am worried
about the overhead of using lists as node structures. For most spatial
calculations (variograms, polygon adjacency, weight matrices, neighbor
finding etc.) trees are essential for better than O(n^2) performance.

I hope my comments are construed as constructive rather than whining. Most
of what I have indicated I would be willing to help implement.

Nicholas 


                 CH3
                  |
                  N             Nicholas Lewin-Koh
                 / \            Dept of Statistics
           N----C   C==O        Program in Ecology and Evolutionary Biology
          ||   ||   |           Iowa State University
          ||   ||   |           Ames, IA 50011
          CH    C   N--CH3      http://www.public.iastate.edu/~nlewin
            \  / \ /            nlewin@iastate.edu
             N    C
             |   ||             Currently
            CH3   O             Graphics Lab
                                School of Computing
                                National University of Singapore
     The Real Part of Coffee    kohnicho@comp.nus.edu.sg


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[Rd] New Web page -- Ideas list
Nicholas Lewin-Koh