Dear All, here a problem I think many of you can solve in few minutes.
I have a dataframe which contains values of plot id, diameters, heigths and basal area of trees, thus columns names are: id | dbh | h | g head(ipso, n=10) id dbh h g 1 FPE0164 36 13.62 0.10178760 2 FPE0164 31 12.70 0.07547676 21 FPE1127 57 18.85 0.25517586 13 FPE1127 39 15.54 0.11945906 12 FPE1127 34 14.78 0.09079203 6 FPE1127 32 15.12 0.08042477 5 FPE1127 28 14.13 0.06157522 15 FPE1127 27 13.50 0.05725553 19 FPE1127 25 13.28 0.04908739 11 FPE1127 19 11.54 0.02835287 from here I need to calculate the mean of the six greater g_ith for each id_ith. The clauses are that: if length(id) >=6 do the mean of the first six greaters g else do the mean of all the g_ith in the id_ith (in head print above e.g. for the id==FPE0164 do the mean of just these two values of g). The g are already ordered by id ascending and g descending using: ipso <- ipso[with(ipso, order(ipso$id, -ipso$g)), ] # Order for id ascending and g descending I tried a lot of for loops and tapply() without results. Can anyone help me to solve this? Thanks for your attention Best whishes Matteo [[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.