[R] R is not for Relational

Peter Dalgaard BSA p.dalgaard at biostat.ku.dk
Tue Aug 3 22:44:17 CEST 1999


Russell Senior <seniorr at teleport.com> writes:

> Peter> Check if subset() does something in the right direction. What
> Peter> would the select statement do, precisely? (I don't speak SQL)
> 
> One useful thing that subset() doesn't appear to do is joins.  That is
> frequently what select statements are used for in SQL.  There are
> three S-plus functions (at least, as documented in MASS 2ed) called
> merge, by and aggregate.  The merge() function joins data frames, but
> is not implemented in R that I am aware of, at least as of 0.64.0.

Hmm. What does the SQL syntax (and semantics) look like for that kind
of operation? Would it make sense to try and turn the existing
subset() into a select() function which could do joins as well?

-- 
   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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