HI, You can also use these in addition to aggregate: tapply(dat$x,INDEX=dat[grp],mean) library(plyr) ddply(dat,.(dat[grp]$a,dat[grp]$d),summarize,mean(x)) # dat[grp]$a dat[grp]$d ..1 #1 b c 0.26781378 #2 b d -0.01994023 #3 c e 0.14874737 #4 d d -0.21051512 #5 e b 0.18821072
A.K. ----- Original Message ----- From: Xianming Wei <x...@bses.com.au> To: "r-help@r-project.org" <r-help@r-project.org> Cc: Sent: Thursday, August 30, 2012 10:37 PM Subject: [R] dynamic list in aggregate() Hi all, How can I have a dynamic list for different combinations of grouping factors in the following example? Thanks. dat <- data.frame(x=rnorm(100), a=sample(letters[1:5], replace = T), b=sample(letters[1:5], replace = T), c=sample(letters[1:5], replace = T), d=sample(letters[1:5], replace = T)) ## define grouping factors grp <- c('a','d') # or any combination among a, b, c and d ## something like this for the list lst <- paste('dat$', grp, sep='', collapse =',') ## aggregate on the defined list aggregate(dat$x, list(lst), mean) Thanks. Regards, Xianming -------------------- Internet e-Mail Disclaimer -------------------- PRIVILEGED - PRIVATE AND CONFIDENTIAL: This email and any files transmitted with it are intended solely for the use of the addressee(s) and may contain information, which is confidential or privileged. If you are not the intended recipient, be aware that any disclosure, copying, distribution, or use of the contents of this information is prohibited. In such case, you should destroy this message and kindly notify the sender by reply e-mail. The views and opinions expressed in this e-mail are those of the sender and do not necessarily reflect the views of the company. VIRUSES: Email transmission cannot be guaranteed to be secure or error free, as information may be intercepted, corrupted, lost, destroyed, arrive late or incomplete or contain viruses. This email and any files attached to it have been checked with virus detection software before transmission. You should nonetheless carry out your own virus check before opening any attachment. BSES Limited does not represent or warrant that files attached to this email are free from computer viruses or other defects and accepts no liability for any loss or damage that may be caused by software viruses [[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. ______________________________________________ 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.