[R] programming question

[Peter Dalgaard BSA]

Clayton Springer <csprin at brandybuck.ca.sandia.gov> writes:

> Dear r-help,
> 
> I am trying to build a new function (to process rpart objects) that will
> output matrix that has a row for each node and a column for
> each feature. With each entry in the table is a numerical property
> at that node for that feature (e.g. surrogate split agreement, improvement).
> 
> My current trouble is that the only clue to the identity of the feature is 
> stored as the *name* of the feature.  Whereas a table is indexed by *number*.
> 
> I have a list of sorted names, but I am having trouble translating a name
> into a number. If this where perl the answer would be a hash.
> 
> Or can I directly index a table with an alphanumeric string. (ie. a hash).
> 
> Any help would be greatly appreciated,

You can easily index with names:

> x<-1:3
> names(x)<-letters[1:3]
> x
a b c 
1 2 3 
> x["b"]
b 
2 

It's not a hash in the perl sense, though. Each lookup does a linear
search. The match() function could also be used.

-- 
   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
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._