Hi, You could try: library(dplyr)
A %.% group_by(author_id) %.% arrange(desc(prob)) %.% summarise(paper_id=paste(paper_id,collapse=",")) A.K. On Thursday, March 27, 2014 11:40 AM, Rohit Gupta <rhtgpt...@gmail.com> wrote: I have a data A which looks like author_id paper_id prob 731 24943 1 731 24943 1 731 688974 1 731 964345 .8 731 1201905 .9 731 1267992 1 736 249 .2 736 6889 1 736 94345 .7 736 1201905 .9 736 126992 .8 The output I am desiring is: author_id paper_id 731 24943,24943,688974,1201905,964345 736 6889,1201945,126992,94345,249 That is paper_id are arranged according to decreasing order of probability.How could this be done? Thanks [[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.