Is there a way to apply a function, say cor(), to each combination of some number of variables, and this, without using loops? For example, I have day, hour, var1 and var2. How could I compute cor(var1,var2) for each day*hour combination and obtain a matrix with day, hour and the cor value for each combination? Thanks for your time, Marc ==================Marc Bélisle Professeur adjoint Chaire de recherche du Canada en écologie spatiale et en écologie du paysage Département de biologie Université de Sherbrooke 2500 Boul. de l'Université Sherbrooke, Québec J1K 2R1 Canada Tél: +1-819-821-8000 poste 1313 Fax: +1-819-821-8049 Courriél: Marc.M.Belisle@USherbrooke.ca [[alternative HTML version deleted]]
jeaneid@chass.utoronto.ca
2005-Mar-02 19:55 UTC
[R] Applying a function to all combinations of factors
you could use something like by(data, list(data1$day, data1$hour), function(x) cor(x[,"var1"], x[, "var2"])) This will return a list and then you can unlist and turn to matrix HTH> Is there a way to apply a function, say cor(), to each combination of some > number of variables, and this, without using loops? > > For example, I have day, hour, var1 and var2. How could I compute > cor(var1,var2) for each day*hour combination and obtain a matrix with day, > hour and the cor value for each combination? > > Thanks for your time, > > Marc > > ==================Marc B?lisle > Professeur adjoint > Chaire de recherche du Canada en ?cologie spatiale et en ?cologie du > paysage > D?partement de biologie > Universit? de Sherbrooke > 2500 Boul. de l'Universit? > Sherbrooke, Qu?bec > J1K 2R1 Canada > > T?l: +1-819-821-8000 poste 1313 > Fax: +1-819-821-8049 > Courri?l: Marc.M.Belisle at USherbrooke.ca > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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 >