Thank you, I am sorry but I am still trying to figure out how to make the function work.
I have a column called tUnitsort$BlockNumber which can range from 0 to 6. I have another two columns with the date and the hour ending for the given day. Example Date Hour BlockNumber MyTo NewColumn 2011-01 1 2 140 140 2011-01 1 1 70 140 2011-01 1 0 0 140 2011-02 1 2 160 160 2011-02 1 1 70 160 2011-02 1 0 0 160 2011-03 1 2 150 150 I want to create a NewColumn which will place the MyTo number for the highest block number for the rest blocks in a given hour ending within a day. ifelse(tUnitsort[,4]>=tUnitsort[-1,4],tUnitsort[,7],tUnitsort[-1,7]) I am unsure how to refference the element before in this case. I thought the -1 was doing this but I believe I'm wrong now. http://r.789695.n4.nabble.com/file/n4636337/BR3_2011_New.csv BR3_2011_New.csv -- View this message in context: http://r.789695.n4.nabble.com/remove-loop-which-compares-row-i-to-row-i-1-tp4635327p4636337.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.