[R] "Glueing" factors together

Peter Dalgaard p.dalgaard at biostat.ku.dk
Tue Jun 15 10:35:29 CEST 2004

(Ted Harding) <Ted.Harding at nessie.mcc.ac.uk> writes:

> then I'd like to end up with a single factor with levels
>   A0B0, A0B1, A0B2, A1B0, A1B1, A1B2
> according to all the combinations which actually occur in the
> data (e.g. if (A1,B2) did not occur in the data, then A1B2 would
> not be a level in the resulting "glued" factor).
> I can see clumsy and tedious ways involving manipulating strings,
> paste(), etc.; but I'm sure it must be possible more elegantly.

You mean like interaction()?

   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

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