[R-sig-Geo] subset of spatial points

[Johannes Radinger]

Hello,

I tried to follow your and Ken's suggestions but I still fail and
I can't find the source for the problem. 

I attached the script and the data (path to load the data in the script
must be changed). Maybe there is just a small mistake
in the script but I tried to find the problem now for
some hours but can't find  it... Maybe someone of you
has some hints and you can help me please.

best regards,
Johannes


-------- Original-Nachricht --------
> Datum: Thu, 02 Feb 2012 15:24:30 +0100
> Von: Tom Gottfried <tom.gottfried at tum.de>
> An: r-sig-geo at r-project.org
> Betreff: Re: [R-sig-Geo] subset of spatial points

> As a workaround you could do
> 
> subset(df,df$Attr == i)
> 
> or what Ken suggested.
> 
> regards,
> Tom
> 
> Am 02.02.2012 12:51, schrieb Johannes Radinger:
> > Hello,
> >
> > I tried to subset a spatial points dataframe with:
> > subset(df,Attr == i)
> > but then I get the error:
> > "Fehler in subset.SpatialPointsDataFrame(df, Attr == i) :
> >    Objekt 'Attr' nicht gefunden"
> >
> > so it the object 'Attr' couldn't be found. There is definetly
> > a column called 'Attr' in the spatialpointsdataframe. This is also
> > proofed when I transform my spatial points into a ordinary dataframe
> before everything works (there is the column 'Attr'):
> > df<- as.data.frame(df)
> >
> >
> > It gets strange now:
> > when I tried to make a short sample script... everything
> > works, so I don't know why the 'Attr' couldn't be found in
> > my script although it exists...??
> >
> > library(rgdal)
> >
> > X<- c(9.3182,9.31609,9.29932, 9.14613, 9.32783)
> > Y<- c(54.6461, 54.439, 54.4786, 54.6561, 54.5668)
> > Attr<- factor(c("A","A","B","C","C"))
> >
> > df<- data.frame(X,Y,Attr)
> > coordinates(df)<- c("X", "Y")
> > proj4string(df)<- CRS("+proj=longlat +datum=WGS84 +ellps=WGS84
> +towgs84=0,0,0")
> >
> > select.Attr<- names(table(df$Attr)[table(df$Attr)>1])
> >
> > for(i in select.Attr){
> > 	X<- subset(df,Attr == i)
> > 	print(X)
> > 	}
> >
> > Any suggestions?
> >
> > best regards,
> > /johannes
> > --
> >
> > _______________________________________________
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> > R-sig-Geo at r-project.org
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> 
> -- 
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> Department für Pflanzenwissenschaften
> Lehrstuhl für Grünlandlehre
> Alte Akademie 12
> 85350 Freising / Germany
> Phone: ++49 (0)8161 715324
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> email: tom.gottfried at wzw.tum.de
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