Hi, On Friday 28 July 2006 20:21, Horace Tso wrote: > Unless there is another level of complexity that i didn't see here, > wouldn't it be a simply application of sapply as follow, > > sapply( 1:dim(M2)[[1]], function(x) M1[M2[x,1], M2[x,2]] )
Andy's previous answer involving matrix indexing (M1[M2]) is simpler but just for the sake of it, since we're dealing with matrices it is not a case of sapply but of _apply_: apply(M2, 1, function(x) M1[x[1], x[2]]) My 2c, Adrian -- Adrian DUSA Arhiva Romana de Date Sociale Bd. Schitu Magureanu nr.1 050025 Bucuresti sectorul 5 Romania Tel./Fax: +40 21 3126618 \ +40 21 3120210 / int.101 ______________________________________________ R-help@stat.math.ethz.ch 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.