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$Attr == i)
or what Ken suggested.
regards,
Tom
Am 02.02.2012 12:51, schrieb Johannes Radinger:
Hello,
I tried to subset a spatial points dataframe with:
subset(df,Attr == i)
but then I get the error:
"Fehler in subset.SpatialPointsDataFrame(df, Attr == i) :
Objekt 'Attr' nicht gefunden"
so it the object 'Attr' couldn't be found. There is definetly
a column called 'Attr' in the spatialpointsdataframe. This is also
proofed when I transform my spatial points into a ordinary dataframe
before everything works (there is the column 'Attr'):
df<- as.data.frame(df)
It gets strange now:
when I tried to make a short sample script... everything
works, so I don't know why the 'Attr' couldn't be found in
my script although it exists...??
library(rgdal)
X<- c(9.3182,9.31609,9.29932, 9.14613, 9.32783)
Y<- c(54.6461, 54.439, 54.4786, 54.6561, 54.5668)
Attr<- factor(c("A","A","B","C","C"))
df<- data.frame(X,Y,Attr)
coordinates(df)<- c("X", "Y")
proj4string(df)<- CRS("+proj=longlat +datum=WGS84 +ellps=WGS84
select.Attr<- names(table(df$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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