Hi R-users: [R 2.2 on OSX 10.4.3] I have a (sparse) vegetation data frame with 500 rows (sampling units) and 177 columns (plant species) where the data represent % cover. I need to summarize the cover data by returning the names of the most dominant and the second most dominant species per plot. I reduced the data frame to omit cover below 5%; this is what it looks like stacked. I have experimented with tapply(), by(), and some functions mentioned in archived postings, but I haven't seen anything that answers to this directly. Does anybody have any ideas?
OBJECTID PolygonID SpeciesCod AbundanceP 1 15006 ANT-CBG-rr1 Leymol 5.00000 3 15008 ANT-CBG-rr1 Ambcha 5.00000 5 15010 ANT-ESH-27 Atrpat 20.00000 6 15011 ANT-ESH-27 Ambcha 10.00000 11 15016 ANT-ESH-28 Salvir 20.00000 14 15019 ANT-ESH-28 Atrpat 5.00000 18 15023 ANT-POR-Rubarm5 Rubarm 60.00000 19 15024 ANT-POR-Rubarm5 Hedhel 40.00000 25 15030 ECO-CBG-A2 Griint 5.00000 27 15032 ECO-CBG-A2 Anngra 5.00000 38 15043 ECO-CBG-A4 Sperub 50.00000 Regards, Graham Watt-Gremm ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html