[EMAIL PROTECTED] >I was wondering if I can avoid a time-consuming for loop on my 600000 >obs dataset.
>school_id y >8 9.87 >8 8.89 >8 7.89 >8 8.88 >20 6.78 >20 9.99 >20 8.79 >31 10.1 >31 11 >There are, say, 143 different schools in this 600000 obs dataset. >I need to thave sequential identifiers, 1,2,3,4,5,...,143. Hello, Toby. Maybe: dta$id <- cumsum(c(1, diff(dta$school_id) != 0)) -- François Pinard http://pinard.progiciels-bpi.ca ______________________________________________ [email protected] 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.
