You could also use match() directly instead of going through factors. Any of the following would map your inputs to small integers
> match(x, x)-1 [1] 0 1 0 3 0 5 0 7 8 9 > match(x, unique(x))-1 [1] 0 1 0 2 0 3 0 4 5 6 > match(x, sort(unique(x)))-1 [1] 3 4 3 6 3 2 3 0 5 1 Your numbers are pretty big, c. 2^46. If you get bigger than 2^53 you won't always be able to distinguish between adjacent numbers > (2^53 + 5) == (2^53 + 4) [1] TRUE so you may want to input them as character strings. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf Of David Winsemius > Sent: Thursday, September 01, 2011 9:24 AM > To: Thomas Chesney > Cc: r-help@r-project.org > Subject: Re: [R] Automatic Recoding > > > On Sep 1, 2011, at 10:54 AM, Thomas Chesney wrote: > > > I have a text file full of numbers (it's a edgelist for a graph) and > > I would like to recode the numbers as they are way too big to work > > with. So for instance the following: > > > > 676529098667 1000198767829 > > 676529098667 100867672856227 > > 676529098667 91098726278 > > 676529098667 98928373 > > 1092837363526 716172829 > > > > would become: > > > > 0 1 > > 0 2 > > 0 3 > > 0 4 > > 5 6 > > > > i.e. all 676529098667 would become 0, all 1000198767829 would become > > 1 etc. > > Depending on how that set of numbers was entered see if this is helpful: > > 1) First entering across first then down. > > x <- c(676529098667 , 1000198767829, > 676529098667 , 100867672856227, > 676529098667 , 91098726278, > 676529098667 , 98928373, > 1092837363526 ,716172829) > as.numeric(factor(x, levels=unique(x)) ) > # [1] 1 2 1 3 1 4 1 5 6 7 > > 2( Now entering first down then over. > > x2 <- matrix(x, ncol=2, byrow=TRUE) # Matrices are column first > ordered. > > as.numeric(factor(x2, levels=unique(c(x2))) ) # need c() to avoid > warning. > # [1] 1 1 1 1 2 3 4 5 6 7 > > > If I read all the values into a matrix, is there a pre-existing > > function that can do the recoding? > > You can just subtract one from the factor results. The trick is to use > explicit levels determined to match the sort order you want. Other > wise the levels would be first collated. > > -- > David Winsemius, MD > West Hartford, CT > > ______________________________________________ > 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.
