[GRASS-user] r.regression.multi for logistic regression - it is possible?
nunocesardesa at gmail.com
Fri Sep 5 03:11:42 PDT 2014
Never done it in Grass but its a typical operation.
For me it seems a bit confusing with for me since you are not showing me a
glm fitting but instead just using the occurrence map in the logistic link
What you need to do is to fit a GLM to the binary data you have, something
you can do in R for example check here:
Then you will build your output in grass using the r.mapcalc: F(x) = 1 / (
1+ e^(-GLM) (That will be your probability map).
But, you can actually do everything using R only, no need to come into
grass but you can if you want.
On 5 September 2014 10:46, Roberto Marzocchi <roberto.marzocchi at gmail.com>
> Dear all,
> I have dichotomous data (occurrence 1 and non-occurence 0) and I want to
> use the logistic regression method in order to obtain susceptibility map
> of landslide occurrence.
> I try to use r.regression.multi, but I am not sure to correctly define the
> mapy variable..
> I try to use r.mapcalc
> obtaining a map that go from -11.5 (not occurrence) to +11.5 (occurrence)
> when I try to use r.regression.multi I obtain a lot of null values in
> residuals and estimates map.
> i do not understand why..
> Thanks in advanced for the attention
> grass-user mailing list
> grass-user at lists.osgeo.org
Nuno César de Sá
+351 91 961 90 37
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