[R-sig-Geo] Linking lm residuls to specific polygon in shape files

[David Martell]

Hello Roger,

Yes, that's very helpful.

Thanks very much,

Dave Martell


On Mon, 14 Aug 2006, Roger Bivand wrote:

> On Mon, 14 Aug 2006, David Martell wrote:
>
> >
> > I am using the lm.morantest procedure in spdep to test for spatial
> > autocorrelation in my lm residuals.
> >
> > I am not sure where this procedure gets the residuals.
> >
> > I have prepared a GIS coverage that has a .shp file.  I ran the lm model,
> > produced the residuals, then put them them in the GIS coverage.
> >
> >
> > When I run lm in my R program, it produces an lm object that also contains
> > the residuals.
> >
> >
> > Does lm.morantest get the residuals from the .shp file or the lm object.
> >
> > If it gets them from the latter, how does it determine which residual is
> > assigned to which polygon in the .shp file.
>
> lm.morantest() uses the whole "lm" object returned by lm(), so the
> residuals are by definition in the same order as the variables included in
> the model formula. If you need tight control, do something like this:
>
> xx <- readShapePoly(system.file("shapes/columbus.shp",
>   package="maptools")[1], IDvar="NEIGNO")
> row.names(as(xx, "data.frame"))
> xx_nb <- poly2nb(as(xx, "SpatialPolygons"))
> attr(xx_nb, "region.id")
> lm_obj <- lm(CRIME ~ INC + HOVAL, data=xx)
> names(residuals(lm_obj))
> lm.morantest(lm_obj, nb2listw(xx_nb), spChk=TRUE)
>
> where spChk=TRUE checks the equality of the names of the residuals of the
> "lm" object (taken from the data= object of the call to lm()) with the
> "region.id" attribute of the neighbour list. From the time the sapefile is
> read, it has nothing more to do with the SpatialPolygonsDataFrame object
> (here xx). Doing something like:
>
> xx$lm_obj_resids <- residuals(lm_obj)
>
> and then
>
> writePolyShape(xx, "newshape")
>
> includes them in a new shapefile.
>
> Does this clarify things?
>
> Roger
>
> >
> > Thanks,
> >
> > Dave Martell
> >
> > _____________________________________________________________
> >
> > David L. Martell, Professor
> > Faculty of Forestry, University of Toronto
> > 33 Willcocks Street, Toronto, Ontario, Canada, M5S 3B3
> >
> > E-mail:  martell at smokey.forestry.utoronto.ca
> > URL:     http://www.firelab.utoronto.ca
> > Phone:   (416) 978-6960
> > Fax:     (416) 978-3834
> > Map:     ES on campus map at http://oracle.osm.utoronto.ca/map/
> >
> > _______________________________________________
> > R-sig-Geo mailing list
> > R-sig-Geo at stat.math.ethz.ch
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >
>
> --
> Roger Bivand
> Economic Geography Section, Department of Economics, Norwegian School of
> Economics and Business Administration, Helleveien 30, N-5045 Bergen,
> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
> e-mail: Roger.Bivand at nhh.no
>
>

_____________________________________________________________

David L. Martell, Professor
Faculty of Forestry, University of Toronto
33 Willcocks Street, Toronto, Ontario, Canada, M5S 3B3

E-mail:  martell at smokey.forestry.utoronto.ca
URL:     http://www.firelab.utoronto.ca
Phone:   (416) 978-6960
Fax:     (416) 978-3834
Map:     ES on campus map at http://oracle.osm.utoronto.ca/map/