"conditional duplicates"?
Many Thanks!
Dimitris Rizopoulos wrote:
Hi Christian, may be this is helpful: dat <- data.frame(id=rep(1:4, each=5), smonth=sample(1:5, 20, TRUE)) dat$duplicated <- unlist(tapply(dat$smonth, dat$id, duplicated)) dat Best, Dimitris ---- Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/16/396887 Fax: +32/16/337015 Web: http://www.med.kuleuven.ac.be/biostat/ http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm ----- Original Message ----- From: "Christian Schulz" <ozric at web.de> To: <r-help at stat.math.ethz.ch> Sent: Wednesday, November 10, 2004 1:52 PM Subject: [R] "conditional duplicates"?
Hi,
i would like check a repeated measurement dataset, whether
cases (which (id) could be more than one time included and not all
same times included.)
have more than one times the same SMONTH!?
#This pseudo code didn't work with a for loop, because the [i+1]
isn't known.
How i could refer to [i+1] ?
if(ID[i] == ID[i+1] & SMONTH[i] !=[i+1]) {res[i] <- 0 }
if(ID[i] == ID[i+1] & SMONTH[i] == [i+1]) {res[i] <- 1 }
many thanks,
christian
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