HI Not sure whether this helps: ipso<- read.table(text=" 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 ",sep="",header=TRUE,stringsAsFactors=FALSE)
library(plyr) ddply(ipso,.(id),summarize,g=mean(head(g,6))) # id g #1 FPE0164 0.08863218 #2 FPE1127 0.11078041 aggregate(g~id,ipso,function(x) mean(head(x,6))) # id g #1 FPE0164 0.08863218 #2 FPE1127 0.11078041 >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 ______________________________________________ [hidden email] 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. ______________________________________________ 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.
