Hi changing list to matrix and making summary could do the trick
lll <- list(a=cbind(1:10, rnorm(10)), b=cbind(1:10, rnorm(10))) mat <- do.call("rbind", lll) tapply(mat[,2], mat[,1], mean) BTW I found a suitable thread with similar question in CRAN search list summary mean HTH Petr On 7 Dec 2005 at 22:38, Rhett Eckstein wrote: Date sent: Wed, 7 Dec 2005 22:38:56 +0800 From: Rhett Eckstein <[EMAIL PROTECTED]> To: r-help@stat.math.ethz.ch Subject: [R] How to simplify > Dear list, > I have a list containing parameters (time and X1), and have "n" > similar data set like > the following: > > cal > [[1]] > time X1 > 1 0.0 10.006306 > 2 0.5 9.433443 > 3 1.0 8.893405 > 4 2.0 7.904274 > 5 4.0 6.243807 > 6 6.0 4.932158 > 7 8.0 3.896049 > 8 10.0 3.077604 > > [[2]] > time X1 > 1 0.0 10.015972 > 2 0.5 9.460064 > 3 1.0 8.935039 > 4 2.0 7.970755 > 5 4.0 6.343151 > 6 6.0 5.047900 > 7 8.0 4.017131 > 8 10.0 3.196856 > > [[3]] > time X1 > 1 0.0 9.985741 > 2 0.5 9.552583 > 3 1.0 9.138239 > 4 2.0 8.362664 > 5 4.0 7.003394 > 6 6.0 5.865057 > 7 8.0 4.911747 > 8 10.0 4.113382 > > [[4]] > ....... > > [[n]] > ....... > > And I would like to put all X1( when time=0) together, time=0.5,1... > are the same. then calculate the mean value. > a<-list() > b<-list() > > c<-list() > d<-list() > e<-list() ....... > for(i in 1:n){ + > a[[i]]<-cal[[i]][1,2] + b[[i]]<-cal[[i]][2,2] + > c[[i]]<-cal[[i]][3,2] + d[[i]]<-cal[[i]][4,2] + > e[[i]]<-cal[[i]][5,2] + ......... } > >mean.a<-(a[[1]][1]+a[[2]][1]+a[[3]][1]+.....)/n > >mean.b<-(b[[1]][1]+b[[2]][1]+b[[3]][1]+.....)/n > >mean.c<-(c[[1]][1]+c[[2]][1]+c[[3]][1]+.....)/n > >mean.d<-(d[[1]][1]+d[[2]][1]+d[[3]][1]+.....)/n >............. > >xy<-c(mean.a,mean.b,mean.c,mean.d,........) But the way I use seem > not very smart. So please give me some hints to the simplify this. > Thanks in advance !! Sincerely!! > > ______________________________________________ > 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 Petr Pikal [EMAIL PROTECTED] ______________________________________________ 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