Hi [EMAIL PROTECTED] napsal dne 13.11.2007 23:29:25:
> Sorry to hijack this thread. I have a similar but slightly different > situation. Using the original poster's example, how to elegantly get > the mean of column V2 when column V1 is either A or C and F1 is 0? I do not fully understand. You want to select subset of a data frame and then to compute column mean? If yes just use ?subset or construct a logical vector according to your condition lll <- (V1 == "A" | V1 == "B") & F1 == 0 mean(data[lll,"V2"]) Regards Petr > > Thanks, > Gang > > > On Nov 13, 2007, at 5:30 AM, Petr PIKAL wrote: > > Hi > > > > [EMAIL PROTECTED] napsal dne 13.11.2007 10:59:09: > > > >> Dear list, > >> > >> I have this dataframe > >> > >> V1 V2 F1 > >> 1 A 2 0 > >> 2 A 3 0 > >> 3 A 4 1 > >> 4 B 3 0 > >> 5 B 2 1 > >> 6 C 6 0 > >> 7 C 2 0 > >> 8 C 6 0 > >> > >> and would like to calculate a new column > >> with mean-values, following this rule > >> > >> 1. If F1 = 0 calculate the mean from V2 > >> for each factor in V1. > >> > >> 2. If F1 = 1, then F1_mean = 0 > >> > >> So, the new DF should look like this > >> > >> V1 V2 F1 F1_mean > >> 1 A 2 0 2.5 > >> 2 A 3 0 2.5 > >> 3 A 4 1 0.0 > >> 4 B 3 0 3.0 > >> 5 B 2 1 0.0 > >> 6 C 6 0 7.0 > >> 7 C 2 0 7.0 > >> 8 C 6 0 7.0 > > > > I would use ave for computing mean for combination of V1 and F1 and > > then I > > put all values of F1_mean for which F1 is 1 to 0 > > > > test$F1_mean <- ave(test$V2, test$V1, factor(test$F1), FUN = mean) > > test$F1_mean[test$F1==1] <- 0 > > > > Regards > > Petr > > > >> > >> Thank you for any help! > >> > >> Patrick Hausmann > > > > [[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.
