Hi all, There must be a really obvious R solution to this, but I can't figure out how to aggregate a list. For instance, if I read.table the following from a file: Val1 Val2 A 3 4 A 5 6 B 4 4 I would like to take the mean (or median) across any/all rows of type "A" to end up with the structure: Val1 Val2 A 4 5 B 4 4 in this case. How would I go about doign that w/o doing a loop or putting into a DB and using SQL to do this? Thanks for any suggestions, or pointers at appropriate functions I should be reading the documentation on. Paul -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
Aggregating a List
2 messages · Paul Boutros, Peter Dalgaard
Paul Boutros <pcboutro at engmail.uwaterloo.ca> writes:
Hi all, There must be a really obvious R solution to this, but I can't figure out how to aggregate a list. For instance, if I read.table the following from a file: Val1 Val2 A 3 4 A 5 6 B 4 4 I would like to take the mean (or median) across any/all rows of type "A" to end up with the structure: Val1 Val2 A 4 5 B 4 4 in this case. How would I go about doign that w/o doing a loop or putting into a DB and using SQL to do this? Thanks for any suggestions, or pointers at appropriate functions I should be reading the documentation on.
aggregate() E.g.,
g <- read.table(stdin(),header=T)
0: gr Val1 Val2 1: A 3 4 2: A 5 6 3: B 4 4 4:
g
gr Val1 Val2 1 A 3 4 2 A 5 6 3 B 4 4
aggregate(g[-1],list(g$gr),mean)
Group.1 Val1 Val2 1 A 4 5 2 B 4 4 or for that matter: aggregate(g[-1],g[1],mean)
O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._