In a data frame I have a column "date" and a column "time",now I want to generate a new column which is the mean of the value of time group by date. In stata the command is egen scalls = mean(time),by(date) but I don't know the command in R, can anybody help me?
Petr PIKAL
2009-Mar-30 09:32 UTC
[R] Odp: How to generate a new column according to some rule?
Hi r-help-bounces at r-project.org napsal dne 30.03.2009 05:17:35:> In a data frame I have a column "date" and a column "time",now I want > to generate a new column which is the mean of the value of time group > by date. In stata the command is > > egen scalls = mean(time),by(date) > > but I don't know the command in R, can anybody help me?In R you can use ?tapply ?by ?aggregate from base or functions from ?doBy package. Regards Petr> > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html> and provide commented, minimal, self-contained, reproducible code.