[R] moving-window (neighborhood) analysis

[Carlos "Guâno" Grohmann]

Hi Milton

thanks for your help

I want to compute a lot of things.. :)
for instance, I want to look at the large scale (regional, non-local)
behavior of slope and aspect, but since aspect is a circular variable,
I can't just go around with mean/median/etc, which are the tools I
have on GIS, so I was hoping I could find some way to define the
moving-window and the apply some function (from a package or
user-defined) to the values within the window (like circular
statistics).

best regards

Carlos
(Brazil / UK)


On 7/1/07, Milton Cezar Ribeiro <milton_ruser at yahoo.com.br> wrote:
>
> Hi Carlos,
>
> What are really you looking for? What you want to compute for the central
> pixel?
> I use FRAGSTATS to compute some landscape metrics using moving windows.
> There you can define circular and rectangular shaped search windows, sized
> as you want.
>
> Kind regards,
>
> Miltinho
> Brazil
>
>
> ----- Mensagem original ----
> De: "Carlos "Guâno" Grohmann" <carlos.grohmann at gmail.com>
> Para: r-help at stat.math.ethz.ch
> Enviadas: Quarta-feira, 27 de Junho de 2007 12:27:28
> Assunto: [R] moving-window (neighborhood) analysis
>
>
> Hello all
>
> I was wondering what would be the best way to do a moving-window
> analysis of a matrix? By moving-window I mean that kind of analysis
> common in GIS, where each pixel (matrix element) of the resulting map
> is a function of it neighbors, and the neighborhood is a square
> matrix.
> I was hoping there was some function in R that could do that, where I
> could define the size of the neighborhood, and then apply some
> function to the values, some function I don't have in GIS packages
> (like circular statistics).
>
> thanks all.
>
> Carlos
>
>
> --
> +-----------------------------------------------------------+
>               Carlos Henrique Grohmann - Guano
>   Visiting Researcher at Kingston University London - UK
>   Geologist M.Sc  - Doctorate Student at IGc-USP - Brazil
> Linux User #89721  - carlos dot grohmann at gmail dot com
> +-----------------------------------------------------------+
> _________________
> "Good morning, doctors. I have taken the liberty of removing Windows
> 95 from my hard drive."
> --The winning entry in a "What were HAL's first words" contest judged
> by 2001: A SPACE ODYSSEY creator Arthur C. Clarke
>
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-- 
+-----------------------------------------------------------+
              Carlos Henrique Grohmann - Guano
  Visiting Researcher at Kingston University London - UK
  Geologist M.Sc  - Doctorate Student at IGc-USP - Brazil
Linux User #89721  - carlos dot grohmann at gmail dot com
+-----------------------------------------------------------+
_________________
"Good morning, doctors. I have taken the liberty of removing Windows
95 from my hard drive."
--The winning entry in a "What were HAL's first words" contest judged
by 2001: A SPACE ODYSSEY creator Arthur C. Clarke