[R] spatial analysis

[Rainer M Krug]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 06/12/11 03:06, Rolf Turner wrote:
> On 06/12/11 01:44, Marianne.ZEYRINGER at ec.europa.eu wrote:
>> Dear all,
>> 
>> I am a PhD student in energy modelling. I am completely stuck
>> with the following problem and would be very grateful for any
>> kind of help. I have cells
> Don't we all?  We're made of them. :-)
> 
> What do you mean by ``I have''?  I.e. be a bit more explicit about 
> the nature of your data.
>> and each cell is assigned a number. I would like to form clusters
>> of cells where the sum of the cell numbers in each cluster must 
>> not exceed 250. One restriction is that only neighbouring cells
> Define "neighbouring".
>> can be formed into clusters. In the end I would like to have a
>> list with all possible cell combinations.
> Do you mean all possible ways in which your ``collection of
> cells'' can be subdivided into such clusters?  My guess is that the
> number of such ways could be extremely large.  (Depending of course
> on how many cells there are in the collection.)
>> Is it possible to do this with R If yes, I would very much
>> appreciate all possible hints how to solve it.
> Install the "fortunes" package.  Then type
> 
> fortune("Yoda")
> 
> But if you want useful help you'll have to make your question much 
> clearer.

Agreed - but as it is a spatial question, you should post it at
r-sig-geo at r-project.org, the list of the special interest group
spatial analysis.

I would also look into e.g. GRASS and SAGA, which might be faster with
these kind of spatial calculations.

In general, if I understand you correctly, you can start with each
cell and then "grow outwards" until you hit your stop criteria (sum <=
250), and then you should have your clusters: one solution per
starting cell (assuming symmetric clusters - if the clusters can be
a-symmetric, many many more).

Cheers,

Rainer


> 
> cheers,
> 
> Rolf Turner
> 
> ______________________________________________ R-help at r-project.org
> mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do
> read the posting guide http://www.R-project.org/posting-guide.html 
> and provide commented, minimal, self-contained, reproducible code.


- -- 
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

Tel :       +33 - (0)9 53 10 27 44
Cell:       +33 - (0)6 85 62 59 98
Fax :       +33 - (0)9 58 10 27 44

Fax (D):    +49 - (0)3 21 21 25 22 44

email:      Rainer at krugs.de

Skype:      RMkrug
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

iEYEARECAAYFAk7d0VYACgkQoYgNqgF2egqOsACfc6CKV1tY/0xbxR41AfwoBMtA
bWsAnRivgAdiuF3MKErvl1l8I+twrOf+
=k9v+
-----END PGP SIGNATURE-----