I have a panel data set defined as a simple data.frame with a factor age and income. I would like to generate the results of a set function such as (sum, mean, or even diff) separate for each factor (category or age group). However I want the result to have the same dimension as the overal data.frame. Therefore, I expect to get repeaded the same result for each item within a category, but different accross categories.
Eg: age income avg_inc 20 100 100 20 90 100 20 110 100 30 200 200 30 250 200 30 150 200 What builtin function can assist in doing this without my having to write loops. I know in Eviews there is the sumsby, meansby, minsby and so forth. -- View this message in context: http://r.789695.n4.nabble.com/Apply-Function-to-List-by-Group-Returning-Result-with-Dim-of-List-tp4311880p4311880.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.