Hi, if you are willing to use dplyr, you can do all in one line of code: library(dplyr) df<-data.frame(id=1:10,A=c(123,345,123,678,345,123,789,345,123,789))
df%>%group_by(unique_A=A)%>%summarise(list_id=paste(id,collapse=", "))->r cheers Am 06.06.2018 um 10:13 schrieb Massimo Bressan: > #given the following reproducible and simplified example > > t<-data.frame(id=1:10,A=c(123,345,123,678,345,123,789,345,123,789)) > t > > #I need to get the following result > > r<-data.frame(unique_A=c(123, 345, 678, > 789),list_id=c('1,3,6,9','2,5,8','4','7,10')) > r > > # i.e. aggregate over the variable "A" and list all elements of the variable > "id" satisfying the criteria of having the same corrisponding value of "A" > #any help for that? > > #so far I've just managed to "aggregate" and "count", like: > > library(sqldf) > sqldf('select count(*) as count_id, A as unique_A from t group by A') > > library(dplyr) > t%>%group_by(unique_A=A) %>% summarise(count_id = n()) > > # thank you > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. > -- Eik Vettorazzi Department of Medical Biometry and Epidemiology University Medical Center Hamburg-Eppendorf Martinistrasse 52 building W 34 20246 Hamburg Phone: +49 (0) 40 7410 - 58243 Fax: +49 (0) 40 7410 - 57790 Web: www.uke.de/imbe -- _____________________________________________________________________ Universitätsklinikum Hamburg-Eppendorf; Körperschaft des öffentlichen Rechts; Gerichtsstand: Hamburg | www.uke.de Vorstandsmitglieder: Prof. Dr. Burkhard Göke (Vorsitzender), Prof. Dr. Dr. Uwe Koch-Gromus, Joachim Prölß, Martina Saurin (komm.) _____________________________________________________________________ SAVE PAPER - THINK BEFORE PRINTING ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.