[R-sig-Geo] Random forest script - problems with training areas polygon?

[Hugo Costa]

Silvia,
you say that the areas of the shapefile are smaller. Do they intersect
pixels centroids? The help of function 'extract' says the following (which
might be relevant for your case?):

If y represents polygons, the extract method returns the values of the
cells of a Raster* object that are covered by a polygon. A cell is covered
if its center is inside the polygon (but see the weights  option for
considering partly covered cells; and argument small for getting values for
small polygons anyway).

Cheers
Hugo

Roman Luštrik <roman.lustrik using gmail.com> escreveu no dia quarta, 7/11/2018
à(s) 15:03:

> Can you make a reproducible example (data, scripts)? Have you tried
> debugging your code?
>
> Cheers,
> Roman
>
> On Wed, Nov 7, 2018 at 2:36 PM Silvia Flaherty <silvia.flaherty using gmail.com>
> wrote:
>
> > Hi all,
> >
> >
> >
> > I have been working with the random forest R script and have had no
> > problems at all up to now.
> >
> > I recently modified the training areas shapefile. It´s actually an edited
> > version of the original shapefile (which worked just fine). Same
> > projection, etc, only the areas are smaller and more specific. That's the
> > only input I changes. The script reads the shapefile but it doesn't do
> the
> > classification.
> >
> >
> >
> > The error  I get is:
> >
> >  Error in `[.data.frame`(satValues, , 2) : undefined columns selected
> >
> >
> >
> > Checking line by line, he problem seems to be (line 139 of the loop):
> >
> > satValues <- extract(satImage, class_data[i,], cellnumbers=TRUE, df=TRUE)
> >
> >
> >
> >
> >
> > I´m not very skilled at using R but I´m quite OK with GIS. I have tried
> > editing the shapefile again, saving it as another file, etc. Same result.
> >
> >
> >
> > Any ideas what could be going wrong?
> >
> > Thanks!
> >
> >
> >
> > Silvia
> >
> >
> > <
> >
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