[R-sig-Geo] subset of spatial points

[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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