[R-sig-Geo] subset of spatial points

[Tom Gottfried]

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
> --
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo at r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo

-- 
Technische Universität München
Department für Pflanzenwissenschaften
Lehrstuhl für Grünlandlehre
Alte Akademie 12
85350 Freising / Germany
Phone: ++49 (0)8161 715324
Fax:   ++49 (0)8161 713243
email: tom.gottfried at wzw.tum.de
http://www.wzw.tum.de/gruenland