[R] recoding large number of categories (select in SAS)

[Philippe Grosjean]

Does

 > ?cut

answers to your question?

Best,

Philippe Grosjean

..............................................<°}))><........
  ) ) ) ) )
( ( ( ( (    Prof. Philippe Grosjean
  ) ) ) ) )
( ( ( ( (    Numerical Ecology of Aquatic Systems
  ) ) ) ) )   Mons-Hainaut University, Pentagone (3D08)
( ( ( ( (    Academie Universitaire Wallonie-Bruxelles
  ) ) ) ) )   8, av du Champ de Mars, 7000 Mons, Belgium
( ( ( ( (
  ) ) ) ) )   phone: + 32.65.37.34.97, fax: + 32.65.37.30.54
( ( ( ( (    email: Philippe.Grosjean at umh.ac.be
  ) ) ) ) )
( ( ( ( (    web:   http://www.umh.ac.be/~econum
  ) ) ) ) )          http://www.sciviews.org
( ( ( ( (
..............................................................

Denis Chabot wrote:
> Hi,
> 
> I have data on stomach contents. Possible prey species are in the 
> hundreds, so a list of prey codes has been in used in many labs doing 
> this kind of work.
> 
> When comes time to do analyses on these data one often wants to regroup 
> prey in broader categories, especially for rare prey.
> 
> In SAS you can nest a large number of "if-else", or do this more cleanly 
> with "select" like this:
> select;
>   when (149 <= prey <=150)   preyGr= 150;
>   when (186 <= prey <= 187)  preyGr= 187;
>   when (prey= 438)                 preyGr= 438;
>   when (prey= 430)                 preyGr= 430;
>   when (prey= 436)                 preyGr= 436;
>   when (prey= 431)                 preyGr= 431;
>   when (prey= 451)                 preyGr= 451;
>   when (prey= 461)                 preyGr= 461;
>   when (prey= 478)                 preyGr= 478;
>   when (prey= 572)                 preyGr= 572;
>   when (692 <= prey <=  695 )                                       
> preyGr= 692;
>   when (808 <= prey <=  826, 830 <= prey <= 832 )      preyGr= 808;
>   when (997 <= prey <= 998, 792 <= prey <= 796)      preyGr= 792;
>   when (882 <= prey <= 909)                          preyGr= 882;
>   when (prey in (999, 125, 994))                             preyGr= 9994;
>   otherwise                             preyGr= 1;
> end; *select;
> 
> The number of transformations is usually much larger than this short 
> example.
> 
> What is the best way of doing this in R?
> 
> Sincerely,
> 
> Denis Chabot
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
> 
>