[R-sig-Geo] subset of spatial points

[Edzer Pebesma]

On 02/02/2012 05:09 PM, Johannes Radinger wrote:
> Hello,
> 
> I tried to follow your and Ken's suggestions 

I don't think you did, as both

for(i in Species.names){
    X <- subset(df_B,df_B$Species == i) # 1st approach
    print(X)
}

and

for(i in Species.names){
    X <- df_B[df_B$Species == i,] # 2nd approach
    print(X)
}

work.


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
>>> --
>>>
>>> _______________________________________________
>>> 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
>>
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> 
> 
> 
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-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
http://www.52north.org/geostatistics      e.pebesma at wwu.de