Take a look at your data. When I loaded what you attached, there were only 9 species that were in common across the two files:
> dim(s16) [1] 226 83 > dim(s15) [1] 96 41 > sum(s15$species %in% s16$species) [1] 10 > sum(s16$species %in% s15$species) [1] 10 > length(intersect(s16$species, s15$species)) [1] 9 > length(unique(s16$species)) [1] 173 > length(unique(s15$species)) [1] 90 > x <- merge(s16, s15, by = 'species') > dim(x) [1] 12 123 > so it is not surprising you got the result that you did. On Thu, Mar 14, 2013 at 6:51 AM, Michael Eisenring <michael.eisenr...@gmx.ch > wrote: > Dear R-help members > > I would be grateful if anyone could help me with the following problem: > > I would like to combine two matrices (Schmitt_15 and Schmitt_16, they are > attached) which have a species presence/absence x sampling plot structure. > The aim would be to have in the end only one matrix which shows all > existing species and their presence/absence on all the different plots. > To do this I used the "merge" function in R. > The problem is that my matrix in the end shows only 12 species (but there > are in total about 100!). I don't know why. > > I used the following commands: > > > Schmitt_15 > Schmitt_16 > output<-merge(Schmitt_15,Schmitt_16,by="species") > write.table(ab,file="output.txt",sep=",") > > Can anyone help me? > Thank you very much! > Michael > > > > > ______________________________________________ > 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. [[alternative HTML version deleted]] ______________________________________________ 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.
