There have been several questions posted on R-sig-Geo about how to
identify connected components (clumps or clusters of contiguous pixels
with the same value) in a pixel image.
The connected component transform has been implemented in the latest
version of package 'spatstat' (version 1.15-3) t
Dear List,
Sorry, this is a second attempt to post the same message. My last one got
scrubbed so I changed browser options. Hopefully this one will make it!
I am using the package adehabitat to analyze the movement patterns and home
range of the manta ray (Manta birostris) in Hawaii. The ma
Dear GeoR Gurus,
I have some raster maps, with continuous values, and I would like
to (1) calculate Local Moran's I ; (2) generate a residual map considering
different lags. I am trying to follow the Bivand and colleague's book,
but I don't know how to generate the neighbour list for each lag.
O
Dear Joshua and Danlin,
your remarks are right, but I am not fully convinced. What are the differences
between using it in an ols framwork and using it in a GWR one under the same
conditions (same bandwith, amount of neighbors...)?
Any further hints?
Thank you and best regards
Marco
Marco,
I agree with Danlin. You can use AIC to compare models of the same
type (i.e. OLS) with different model specifications, or, you can use AIC to
compare models of different types (SAR, OLS, GWR) but with the same model
specification. Alternatively, RMSE can be used to compare mod
Marco:
That's the point - I don't think such comparison is quite appropriate (I
might be wrong) since the model specifications are not the same. You can
compare AICs across OLS, SAR, and GWR with the same specification (same
set of dependent and independent variables), but it's quite doubtful
Dear Danlin and Joshua,
first of all thank you for your replies! Here some further notes for
clarification: I have already estimated a global ols model (based on stepwise
model selection) and because of some spatial effects I recalculated it as
simultaneous autoregressive model. After that I te
Dear Marco,
I think Danlin is more experienced with this than myself, but in
my experience I have found that best global OLS model is usually at
least somewhat different than the best GWR model. I have found that
there is usually a slightly different variable set (at least in the two
data
Dear Marco:
Before doing so, you'll have to ask yourself that whether all those AICs
are comparable among different model specifications. As a matter of
fact, I believe it might be more plausible if you stepwise it first as a
global model (OLS, after all, global models are an "averaged" view o
My original post on this topic was far more detailed but I got very
little response so my second attempt was much more focussed. Here it is
to see if you are able to offer more help:
Sent: 08 May 2009 12:46
To: r-sig-geo@stat.math.ethz.ch
Subject: [R-sig-Geo] Calculating Risk at point locations
(w
Dear list!
I am doing some geographically weighted regression and I am intersted in the
most suitable model (the one with the lowest AIC). Because there is no stepwise
algorithm, I am trying to write a "brute force" function, which uses all
possible variable combination, applies the gwr and ret
Dear All,
Sorry, by mistake I replied to the last message, but this is unrelated.
I hope this is a good place to post this. I'm working through the book
"Applied Spatial Data Analysis with R" and on pg 59 the following code
results in an error
> data(meuse.riv)
> meuse.lst <- list(Polygons(l
Dear All,
I hope this is a good place to post this. I'm working through the book
"Applied Spatial Data Analysis with R" and on pg 59 the following code
results in an error
> data(meuse.riv)
> meuse.lst <- list(Polygons(list(Polygon(meuse.riv))),"meuse.riv")
Error in Polygons(list(Polygon(meus
Sorry, my mistake. This works
data(meuse.riv)
meuse.lst <- list(Polygons(list(Polygon(meuse.riv)),"meuse.riv"))
Fernando Miguez wrote:
Dear All,
Sorry, by mistake I replied to the last message, but this is unrelated.
I hope this is a good place to post this. I'm working through the book
"App
Dear List,
I am using the package adehabitat to analyze the movement patterns and home
range of the manta ray (Manta birostris) in Hawaii. The manta rays in this
study stayed close to shore, often feeding along the shore line or in small
bays. Since they can not go on land (being fish) their
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