Try this: merge(df, subset(df, groupLeader == 1, select = c(groupId, someAttribute)), by = "groupId")[,-5]
On Tue, Dec 22, 2009 at 8:42 AM, Bertolt Meyer <bme...@sozpsy.uzh.ch> wrote: > Dear List, > > I work with multilevel data from psychological group experiments and have > frequently encountered a situation for which I haven't found an elegant > solution: I need to assign the value of a specific group member to all > members of the group. For example, I have a group leader (identified by a > binary vector) and some attribute for all group members. I want to create a > new vector that holds the attribute of the group leader for each individual > in the data frame (code at the bottom of the post): > > personId groupId groupLeader someAttribute leaderAttribute > 1 1 17 0 0.145833333 NA > 2 2 17 1 0.218750000 NA > 3 3 17 0 0.089743590 NA > 4 4 22 0 0.003875969 NA > 5 5 22 0 0.086486486 NA > 6 6 22 0 0.218750000 NA > 7 7 22 1 0.089743590 NA > 8 8 37 1 0.016129032 NA > 9 9 37 0 0.151898734 NA > > I need this: > > personId groupId groupLeader someAttribute leaderAttribute > 1 1 17 0 0.145833333 0.218750000 > 2 2 17 1 0.218750000 0.218750000 > 3 3 17 0 0.089743590 0.218750000 > 4 4 22 0 0.003875969 0.089743590 > 5 5 22 0 0.086486486 0.089743590 > 6 6 22 0 0.218750000 0.089743590 > 7 7 22 1 0.089743590 0.089743590 > 8 8 37 1 0.016129032 0.016129032 > 9 9 37 0 0.151898734 0.016129032 > > So far, my attemps along the lines of > > df$leaderAttribute <- df$someAttribute[df$groupLeader == 1][df$groupId] > > have failed if the groups were not numbered with 1, 2, 3... as in the > example above. I need something simple for transforming the groupId vector > from 17, 17, 17, 22... to 1,1,1,2... for doing the second indexing. It seems > like a simple problem, but I am unable to get it right. I had to fall back > to building a specific function employing nested for() loops for achieving > this. However, this is error prone and very slow, as some of my data sets > are very large. What am I missing? > > Any help would be greatly appreciated. > Regards, > Bertolt > > Code: > > personId <- c(1,2,3,4,5,6,7,8,9) > groupId <- c(17,17,17,22,22,22,22,37,37) > groupLeader <- c(0,1,0,0,0,0,1,1,0) > someAttribute <- c(0.145833333, 0.218750000, 0.089743590, 0.003875969, > 0.086486486, 0.218750000, 0.089743590, 0.016129032, 0.151898734) > leaderAttribute <- c(NA,NA,NA,NA,NA,NA,NA,NA,NA) > > df <- cbind(personId, groupId, groupLeader, someAttribute, leaderAttribute) > df <- as.data.frame(df) > df > > rm(personId, groupId, groupLeader, someAttribute, leaderAttribute, df) > > -- > Dr. Bertolt Meyer > Senior research and teaching associate > Social Psychology, Institute of Psychology, University of Zurich > Binzmuehlestrasse 14, Box 15 > CH-8050 Zurich > Switzerland > > bme...@sozpsy.uzh.ch > tel: +41446357282 > fax: +41446357279 > > ______________________________________________ > 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. > -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O ______________________________________________ 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.
