R help - Dec 2009 - How to figure out which the version of split is used?

There are a number of functions that are dispatched to from split().
> methods('split')
[1] split.data.frame split.Date       split.default    split.POSIXct

Is there a way to figure out which of these variants is actually
dispatched to when I call split? I know that if the argument is of the
type data.frame, split.data.frame will be called? Is it the case that
if the argument is not of type data.frame, Date or POSIXct,
split.default will be called?

On Wed, 9 Dec 2009 19:20:47 -0600 Peng Yu <pengyu.ut at gmail.com>
wrote:
> Is there a way to figure out which of these variants is actually
> dispatched to when I call split? I know that if the argument is of the
> type data.frame, split.data.frame will be called? Is it the case that
> if the argument is not of type data.frame, Date or POSIXct,
> split.default will be called?
Yes. See ?UseMethod

-- 
Karl Ove Hufthammer

On Wed, 09-Dec-2009 at 07:20PM -0600, Peng Yu wrote:

|> There are a number of functions that are dispatched to from split().
|> 
|> > methods('split')
|> [1] split.data.frame split.Date       split.default    split.POSIXct
|> 
|> Is there a way to figure out which of these variants is actually
|> dispatched to when I call split? I know that if the argument is of the
|> type data.frame, split.data.frame will be called? Is it the case that

In R-speak, "class" would be a better word than "type".  

|> if the argument is not of type data.frame, Date or POSIXct,
|> split.default will be called?

I think it's slightly more complicated than that, but you're more or
less on the right track.

HTH

-- 
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   ___    Patrick Connolly   
 {~._.~}                   Great minds discuss ideas    
 _( Y )_  	         Average minds discuss events 
(:_~*~_:)                  Small minds discuss people  
 (_)-(_)  	                      ..... Eleanor Roosevelt
	  
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> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Karl Ove Hufthammer
> Sent: Thursday, December 10, 2009 1:46 AM
> To: r-help at stat.math.ethz.ch
> Subject: Re: [R] How to figure out which the version of split is used?
> 
> On Wed, 9 Dec 2009 19:20:47 -0600 Peng Yu <pengyu.ut at gmail.com>
wrote:
> > Is there a way to figure out which of these variants is actually
> > dispatched to when I call split? I know that if the 
> argument is of the
> > type data.frame, split.data.frame will be called? Is it the 
> case that
> > if the argument is not of type data.frame, Date or POSIXct,
> > split.default will be called?
> 
> Yes. See ?UseMethod
You can also use trace() to see what actually happens
in test cases.  E.g.,
  > invisible(lapply(methods("split"),
      function(method)trace(method,
      bquote(cat("Entering", .(method),
      "x=", class(x), "f=", class(f), "\n")))))
  Tracing function "split.data.frame" in package "base"
  Tracing function "split.Date" in package "base"
  Tracing function "split.default" in package "base"
  Tracing function "split.POSIXct" in package "base"
  > split(data.frame(x=1:3,y=1:3), f=c(10,10,20))
  Tracing split.data.frame(data.frame(x = 1:3, y = 1:3), f = c(10, 10,
.... on entry
  Entering split.data.frame x= data.frame f= numeric
  Tracing split.default(seq_len(nrow(x)), f, drop = drop, ...) on entry
  Entering split.default x= integer f= numeric
  $`10`
    x y
  1 1 1
  2 2 2

  $`20`
    x y
  3 3 3


Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com  
> 
> -- 
> Karl Ove Hufthammer
> 
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