Here is an example of using your data to split it into the subsets and then computing a summary of each subset. You have to remember that what is returned from 'split' is a 'list' of 'data.frames' that as the subsets that you want and then use use 'lapply' to process each of the subsets in the list.
> df <- read.table("C:\\Documents and Settings\\kon9407\\My > Documents\\Downloads\\Baumdaten_aufbereitet (1).csv" + , sep = ';' + , as.is = TRUE + , header = TRUE + ) > # split the data into a list of dataframe > df.s <- split(df, list(df$Plot..ID., df$Baumart), drop = TRUE) > head(names(df.s), 20) [1] "A_2_1.Abies alba" "A_2_2.Abies alba" "A_2_3.Abies alba" "A_2_4.Abies alba" [5] "A_2_5.Abies alba" "A_2_6.Abies alba" "A_3_1.Abies alba" "A_3_4.Abies alba" [9] "A_3_5.Abies alba" "A_3_6.Abies alba" "A_4_1.Abies alba" "A_4_3.Abies alba" [13] "A_4_4.Abies alba" "A_4_5.Abies alba" "A_4_6.Abies alba" "B_1_2.Abies alba" [17] "B_1_4.Abies alba" "B_1_5.Abies alba" "B_1_6.Abies alba" "B_2_4.Abies alba" > df.s[1] $`A_2_1.Abies alba` X Plot..ID. Alter.Neuer.Wald Hoehe..m. Radius..cm. Familie Baumart Deutsch 1 1 A_2_1 2 647 5,64 Kieferngewaechse Abies alba Weisstanne 2 2 A_2_1 2 647 5,64 Kieferngewaechse Abies alba Weisstanne 3 3 A_2_1 2 647 5,64 Kieferngewaechse Abies alba Weisstanne 4 4 A_2_1 2 647 5,64 Kieferngewaechse Abies alba Weisstanne 5 5 A_2_1 2 647 5,64 Kieferngewaechse Abies alba Weisstanne 6 6 A_2_1 2 647 5,64 Kieferngewaechse Abies alba Weisstanne 7 7 A_2_1 2 647 5,64 Kieferngewaechse Abies alba Weisstanne 8 8 A_2_1 2 647 5,64 Kieferngewaechse Abies alba Weisstanne 9 9 A_2_1 2 647 5,64 Kieferngewaechse Abies alba Weisstanne Englisch Umfang..cm. DBH..cm. Gehoelz Bemerkungen Fotos Waldart pointID 1 European silver fir 38 12,09577569 0 NA SEF A_2_SEF 2 European silver fir NA <NA> 1 NA SEF A_2_SEF 3 European silver fir NA <NA> 1 NA SEF A_2_SEF 4 European silver fir NA <NA> 1 NA SEF A_2_SEF 5 European silver fir NA <NA> 1 NA SEF A_2_SEF 6 European silver fir NA <NA> 1 NA SEF A_2_SEF 7 European silver fir NA <NA> 1 NA SEF A_2_SEF 8 European silver fir NA <NA> 1 NA SEF A_2_SEF 9 European silver fir NA <NA> 1 NA SEF A_2_SEF transectID DBH_inch age 1 A_SEF 4,76211641338583 35,7158731003937 2 A_SEF <NA> <NA> 3 A_SEF <NA> <NA> 4 A_SEF <NA> <NA> 5 A_SEF <NA> <NA> 6 A_SEF <NA> <NA> 7 A_SEF <NA> <NA> 8 A_SEF <NA> <NA> 9 A_SEF <NA> <NA> > > lapply(df.s, summary) # notice the names of each of the subsets is printed $`A_2_1.Abies alba` X Plot..ID. Alter.Neuer.Wald Hoehe..m. Radius..cm. Min. :1 Length:9 Min. :2 Min. :647 Length:9 1st Qu.:3 Class :character 1st Qu.:2 1st Qu.:647 Class :character Median :5 Mode :character Median :2 Median :647 Mode :character Mean :5 Mean :2 Mean :647 3rd Qu.:7 3rd Qu.:2 3rd Qu.:647 Max. :9 Max. :2 Max. :647 Familie Baumart Deutsch Englisch Umfang..cm. Length:9 Length:9 Length:9 Length:9 Min. :38 Class :character Class :character Class :character Class :character 1st Qu.:38 Mode :character Mode :character Mode :character Mode :character Median :38 Mean :38 3rd Qu.:38 Max. :38 NA's :8 DBH..cm. Gehoelz Bemerkungen Fotos Waldart Length:9 Min. :0.0000 Length:9 Mode:logical Length:9 Class :character 1st Qu.:1.0000 Class :character NA's:9 Class :character Mode :character Median :1.0000 Mode :character Mode :character Mean :0.8889 3rd Qu.:1.0000 Max. :1.0000 pointID transectID DBH_inch age Length:9 Length:9 Length:9 Length:9 Class :character Class :character Class :character Class :character Mode :character Mode :character Mode :character Mode :character $`A_2_2.Abies alba` X Plot..ID. Alter.Neuer.Wald Hoehe..m. Radius..cm. Min. :12 Length:1 Min. :2 Min. :660 Length:1 1st Qu.:12 Class :character 1st Qu.:2 1st Qu.:660 Class :character Median :12 Mode :character Median :2 Median :660 Mode :character Mean :12 Mean :2 Mean :660 3rd Qu.:12 3rd Qu.:2 3rd Qu.:660 Max. :12 Max. :2 Max. :660 Familie Baumart Deutsch Englisch Umfang..cm. Length:1 Length:1 Length:1 Length:1 Min. :33 Class :character Class :character Class :character Class :character 1st Qu.:33 Mode :character Mode :character Mode :character Mode :character Median :33 Mean :33 3rd Qu.:33 Max. :33 DBH..cm. Gehoelz Bemerkungen Fotos Waldart Length:1 Min. :0 Length:1 Mode:logical Length:1 Class :character 1st Qu.:0 Class :character NA's:1 Class :character Mode :character Median :0 Mode :character Mode :character Mean :0 3rd Qu.:0 Max. :0 pointID transectID DBH_inch age Length:1 Length:1 Length:1 Length:1 Class :character Class :character Class :character Class :character Mode :character Mode :character Mode :character Mode :character $`A_2_3.Abies alba` X Plot..ID. Alter.Neuer.Wald Hoehe..m. Radius..cm. Min. :21.00 Length:10 Min. :2 Min. :662 Length:10 1st Qu.:23.25 Class :character 1st Qu.:2 1st Qu.:662 Class :character Median :25.50 Mode :character Median :2 Median :662 Mode :character Mean :25.50 Mean :2 Mean :662 3rd Qu.:27.75 3rd Qu.:2 3rd Qu.:662 Max. :30.00 Max. :2 Max. :662 Familie Baumart Deutsch Englisch Umfang..cm. Length:10 Length:10 Length:10 Length:10 Min. :14.0 Class :character Class :character Class :character Class :character 1st Qu.:22.0 Mode :character Mode :character Mode :character Mode :character Median :30.5 Mean :31.3 3rd Qu.:35.0 Max. :56.0 DBH..cm. Gehoelz Bemerkungen Fotos Waldart Length:10 Min. :0 Length:10 Mode:logical Length:10 Class :character 1st Qu.:0 Class :character NA's:10 Class :character Mode :character Median :0 Mode :character Mode :character Mean :0 3rd Qu.:0 Max. :0 pointID transectID DBH_inch age Length:10 Length:10 Length:10 Length:10 Class :character Class :character Class :character Class :character Mode :character Mode :character Mode :character Mode :character On Sun, Jul 15, 2012 at 3:01 PM, burton030 <burto...@hotmail.de> wrote: > Hi, > > thanks for your reply but this code just gives me a list but no subsets but > I need subsets because I want to do some calculations with these subsets and > want do make some plots etc. Is there a solution for my problem? I ve posted > an example for the first subset... > > http://r.789695.n4.nabble.com/file/n4636591/A_SEF_Abies_alba.csv > A_SEF_Abies_alba.csv > > -- > View this message in context: > http://r.789695.n4.nabble.com/computing-a-subset-using-a-loop-tp4636564p4636591.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Jim Holtman Data Munger Guru What is the problem that you are trying to solve? Tell me what you want to do, not how you want to do it. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.