a1 * a3[a2] - Niels
Dear R-help list, Sorry to trouble everyone. This seems like it could be achieved with a single command (? variant of apply), but I am not quite seeing it. I am trying to multiply one vector (a1 below) by corresponding values in a3 (as determined by matching element in a vector a2). The example below might be clearer. a1 <- c(4,3,4,6,8,9,2,3,4,6,7,4) a2 <- c("A","A","A","A","B","B","C","C","C","D","D","D") a3 <- c(2,4,1,0.5) names(a3) <- c("A","B","C","D") I would like the vector (8,6,8,12,32,36,2,3,4,3,3.5,2) as my final output result i.e. multiply each element of a1 by the matching a3 as determined by the corresponding element of a2 - that is, for the first 4 elements of a1, multiply by the value 2 found in a3 ("A"), the next 2 by 4 ("B"), the next 3 by 1.0 ("C"), and the last 3 by 0.5 ("D") I am trying to avoid the use of loops, because the actual dataset is much larger. Thanks very much! Min-Han [[alternative HTML version deleted]] ______________________________________________ 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.
On 21/04/11 23.34, Min-Han Tan wrote: -- Niels Richard Hansen Web: www.math.ku.dk/~richard Associate Professor Email: niels.r.han...@math.ku.dk Department of Mathematical Sciences nielsrichardhan...@gmail.com University of Copenhagen Skype: nielsrichardhansen.dk Universitetsparken 5 Phone: +1 510 502 8161 2100 Copenhagen Ø Denmark ______________________________________________ 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.