You might want to look at the doBy package For (1), you could use summaryBy(value~Light+Feed,data=myD, FUN=mean)
and for (2), the transformBy function would be helpful David Freedman Patrick Hausmann wrote: > > Dear list, > > I have two things I am struggling... > > # First > set.seed(123) > myD <- data.frame( Light = sample(LETTERS[1:2], 10, replace=T), > Feed = sample(letters[1:5], 20, replace=T), > value=rnorm(20) ) > > # Mean for Light > myD$meanLight <- unlist( lapply( myD$Light, > function(x) mean( myD$value[myD$Light == x]) ) ) > # Mean for Feed > myD$meanFeed <- unlist( lapply( myD$Feed, > function(x) mean( myD$value[myD$Feed == x]) ) ) > myD > > # I would like to get a new Var "meanLightFeed" > # holding the "Group-Mean" for each combination (eg. A:a = 0.821581) > # by(myD$value, list(myD$Light, myD$Feed), mean)[[1]] > > > # Second > set.seed(321) > myD <- data.frame( Light = sample(LETTERS[1:2], 10, replace=T), > value=rnorm(20) ) > > w1 <- tapply(myD$value, myD$Light, mean) > w1 > # > w1 > # A B > # 0.4753412 -0.2108387 > > myfun <- function(x) (myD$value > w1[x] & myD$value < w1[x] * 1.5) > > I would like to have a TRUE/FALSE-Variable depend on the constraint in > "myfun" for each level in "Light"... > > As always - thanks for any help!! > Patrick > > ______________________________________________ > 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. > > -- View this message in context: http://www.nabble.com/lapply-and-aggregate-function-tp21811834p21812057.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.
