Using package doBy at http://genetics.agrsci.dk/~sorenh/misc/index.html try this:
summaryBy(cbind(length, ratio, monthly1, monthly2) ~ month, DF, max) On 11/8/05, Todd A. Gibson <[EMAIL PROTECTED]> wrote: > Hello, > I have a data manipulation problem that I can easily resolve by using > perl or python to pre-process the data, but I would prefer to do it > directly in R. > > Given, for example: > > month length ratio monthly1 monthly2 > 1 Jan 23 0.1 9 6 > 2 Jan 45 0.2 9 6 > 3 Jan 16 0.3 9 6 > 4 Feb 14 0.2 1 9 > 5 Mar 98 0.4 2 2 > 6 Mar 02 0.6 2 2 > > (FWIW, monthly1 and monthly2 are unchanged for each month) > > I understand how to do aggregations on single fields using split and > sapply, but how can I get entire lines. For example, For the maximum > of data$length grouped by data$month I would like to get back some > form of: > > 2 Jan 45 0.2 9 6 > 4 Feb 14 0.2 1 9 > 5 Mar 98 0.4 2 2 > > For mean, I would like to average all columns: > > Jan 28 0.2 9 6 > Feb 14 0.2 1 9 > Mar 50 0.5 2 2 > > Thank you, > -TAG > Todd A. Gibson > > ______________________________________________ > 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 > ______________________________________________ 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