order matrix by column position
On Thu, Dec 9, 2010 at 5:24 PM, Folkes, Michael
<Michael.Folkes at dfo-mpo.gc.ca> wrote:
Hello all, I'm trying to grasp a way to order a matrix by giving order() only a vector of the columns it can look to for sorting. The approach has to be generic such that I can feed order() a vector of variable length (ie varying # of columns to sort by). x<-rep(1,9) y<-c(1, 1, 2, 2, 2, 1, 2, 2, 2) z<-c(10, 11, 10, 13, ?15,1000,1000, 1001,1002) results<-cbind(x,y,z) #pseudocode: # results[order(vector of column numbers),] # order desired: results[order(results[,1],results[,2],results[,3]),]
Try this: ix <- 1:3 results[do.call(order, as.data.frame(results)[ix]), ] as.data.frame can optionally be omitted if the results object is already a data frame (in your example code its a matrix).
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