Here's a clue: > rank(a) [1] 1 3 4 7 2 5 6 > order(order(a)) [1] 1 3 4 7 2 5 6
W. Bill Venables http://www.cmis.csiro.au/bill.venables/ -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Jun Shen Sent: Monday, 30 March 2009 10:14 AM To: Stavros Macrakis Cc: r-help@r-project.org; Ben Bolker Subject: Re: [R] Sorting problem That's leading to another question: How does rank() work? If I have a character vector a<- c("2a", "2c", "3", "5" , "2b" ,"4a", "4b") Then a[order(a)] returns "2a" "2b" "2c" "3" "4a" "4b" "5", which makes sense But a[rank(a)] returns "2a" "3" "5" "4b" "2c" "2b" "4a", which does not seem to make sense. Similarly, for a numeric vector b<-c( 2, 3, 1 , 6 , 5, 10, 4 , 7 , 9 , 8) b[order(b)] returns 1 2 3 4 5 6 7 8 9 10 b[rank(b)] returns 3 1 2 10 5 8 6 4 9 7 Any explanation? Thanks. On Sun, Mar 29, 2009 at 5:42 PM, Stavros Macrakis <macra...@alum.mit.edu>wrote: > On Sun, Mar 29, 2009 at 5:21 PM, Ben Bolker <bol...@ufl.edu> wrote: > > Adding > > > > xtfrm.numeric <- function(x) {x} > > > > would seem to add the case that people are looking for -- unless > > there's something special that needs to be handled with NAs ??? > > Yes, that was what I was suggesting. xtfrm currently converts NaN to > NA, but that does not seem to be necessary for it to meet its > specification of "producing a numeric vector which will sort in the > same order as 'x'", since sort treats NaNs the same as NAs. > > -s > > ______________________________________________ > 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. > -- Jun Shen PhD PK/PD Scientist BioPharma Services Millipore Corporation 15 Research Park Dr. St Charles, MO 63304 Direct: 636-720-1589 [[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. ______________________________________________ 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.
