On Thu, Sep 4, 2008 at 8:44 PM, Ralph S. <[EMAIL PROTECTED]> wrote: > > Hi all, > > I am trying to create a unique identifier for each row, combining numbers > from three columns. > > Do you know if there is a general formula to do this (or some manual where I > can read about this)? > > I figure I can use the numeric entries of the columns as "coordinates" and > multiply them with different coefficients (different magnitudes) to get the > unique ID - but it would be nice to read about such algorithms in general.
What are you numbers? Are they in a fixed range? Integers or reals? If fixed range integers, it is easy. Think regular numerical representation, e.g. binary, octadecimal, decimal and hexadecimal. For a more generic solution that works with any data types, see e.g. MD5 [http://en.wikipedia.org/wiki/MD5]. It is not guaranteed to generated unique codes, but it is extremely rare that two different inputs gives the same MD5 code. MD5 (and others) are implemented in the 'digest' packages, e.g. > library(digest) > digest(list(a=1, b=list(1:10, c=letters))) [1] "73e0ae066a97bfff7f79d41c65b55fde" My $.02 /Henrik > > Any links/input would be great - > > Ralph > > _________________________________________________________________ > > e. > > [[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.
