Aggregate by First case
try this: dat <- read.table(textConnection( "Id Year 123456 2001 123456 2002 123456 2003 655432 2001 655432 2002 655432 2003"), header = TRUE) closeAllConnections() dat[!duplicated(dat$Id), ] # or dat[tapply(row.names(dat), dat$Id, head, 1), ] I hope it helps. Best, Dimitris ---- Dimitris Rizopoulos Biostatistical Centre School of Public Health Catholic University of Leuven Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/(0)16/336899 Fax: +32/(0)16/337015 Web: http://med.kuleuven.be/biostat/ http://www.student.kuleuven.be/~m0390867/dimitris.htm ----- Original Message ----- From: "Jojje Andersson" <dietaamigo at hotmail.com> To: <r-help at r-project.org> Sent: Friday, May 30, 2008 9:13 AM Subject: [R] Aggregate by First case
Hello! I have an maybe a to a simple question but I cant get it right. I have a dataframe with in one column an id-variable and in another a year-variable. One id-number can occur several years. I have sorted the dataframe on id then on year so the same id-number is sorted by year with the first occurens at top. Now I want to make a subset of this dataframe with just the first year the id-number occur, so the first case of every id. Id Year 123456 2001 123456 2002 123456 2003 655432 2001 655432 2002 655432 2003 Is there a simple command I can do? Thanks! Jojje
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