Here is one way. There will be many ways to do it; I offer this one because it is very general.
-Don tmp <- split(testdata, testdata$personId) myfun <- function(df) { dfo <- df if (any(df$law=='SVG')) dfo$svg <- 1 else dfo$svg <- 0 dfo } tmpo <- lapply(tmp,myfun) testout <- do.call('rbind', tmpo) > print(testout) personId law article svg 1.1 1 SVG 10 1 1.2 1 SVG 10 1 2.3 2 StGB 123 1 2.4 2 StGB 122 1 2.5 2 SVG 10 1 2.6 2 AuG 40 1 2.7 2 StGB 126 1 3 3 SVG 10 1 4.9 4 StGB 111 0 4.10 4 AuG 40 0 -- Don MacQueen Lawrence Livermore National Laboratory 7000 East Ave., L-627 Livermore, CA 94550 925-423-1062 On 3/4/13 7:44 AM, "David Studer" <stude...@gmail.com> wrote: Hello everyone! Does anyone of you know how I could solve the following problem. I guess, it is not a very difficult question, but I simply lack of the right idea: I have a dataset containing data of convictions. This dataset contains 4 columns: - personId: individual number that identifies the offender - law: law which has been violated - article: article which has been violated # Testdata: personId<-c(1,1,2,2,2,2,2,3,4,4) law<-c("SVG", "SVG", "StGB", "StGB", "SVG", "AuG", "StGB", "SVG", "StGB", "AuG") article<-c(10, 10, 123, 122, 10, 40, 126, 10, 111, 40) testdata<-data.frame(personId, law, article) Now I'd like to create three additional dummy-coded columns for each law (SVG, StGB, AuG). For each offender (all offenders have the same personId) it should be checked, whether there are any violations against the three laws. If there are any violations against SVG (for example), then in all rows of this offender the column SVG should have the value 1 (otherwise 0). For example offender 2 has once violated against law "SVG" therefore his four entries should have the value 1 at the column "SVG". I hope you can understand my problem. I'd really appreciate any hints and solutions! Thank you! David [[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.