[R] Substituting functions in package - Lattice

[Saptarshi Guha]

Hi,
	Unfortunately, print.trellis is not exported .
>> environment(print.trellis) <- environment(lattice::print.trellis)

returns "Error: 'print.trellis' is not an exported object from  
'namespace:lattice'"

	I then took the environment of lattice

	search()
	#package:lattice is the 2nd element
	latt<-as.environment(2)
	environment(print.trellis)<-latt
	
	Yet, i get the same error as before when I run print(k), where k is  
a trellis object.

	This is the line in NAMESPACE for lattice (from the source)
	S3method(print,    trellis)

	Thanks
	Saptarshi


Saptarshi Guha | sapsi at pobox.com | http://www.stat.purdue.edu/~sguha


On Mar 6, 2007, at 5:29 PM, Greg Snow wrote:

> You need to set the environment on your version of print.trellis to
> match that of the original (at least that is what has worked for me  
> when
> trying to do modified functions from the trellis package).  Try
> something like:
>
>> environment(print.trellis) <- environment(lattice::print.trellis)
>
> Hope this helps,
>
> -- 
> Gregory (Greg) L. Snow Ph.D.
> Statistical Data Center
> Intermountain Healthcare
> greg.snow at intermountainmail.org
> (801) 408-8111
>
>
>
>> -----Original Message-----
>> From: r-help-bounces at stat.math.ethz.ch
>> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Saptarshi Guha
>> Sent: Tuesday, March 06, 2007 2:55 PM
>> To: R-Help
>> Subject: [R] Substituting functions in package - Lattice
>>
>> Hi,
>> 	I'm trying to learn how a package works but
>> substituting a parituclart function with my own (basically
>> the original one with some debug statements).
>> 	The package is lattice and the method is
>> "print.trellis" which is a
>> S3 method and is not visible.
>> 	To replace this, i sourced a file with the rewritten
>> print.trellis, and the old one was replaced.
>> 	However, i get this error when I attempt to print a
>> trellis object (e.g an xyplot)
>> 	
>> 	Error in assign("last.object", x, env = .LatticeEnv) :
>> 	object ".LatticeEnv" not found
>> 	
>> 	I notice that .LatticeEnv is defined in zzz.R (in the R
>> folder of the lattice source).
>>
>> 	My question, how does one do development on the lattice
>> package without having to recompile everything and install a package?
>>
>> 	I read something about emacs and development (i use
>> emacs) in the zzz.R file
>> 	"## .First.lib will be used if the NAMESPACE file is
>> missing.  This is ## useful during development, thanks to C-c
>> C-l in Emacs/ESS. It won't ## be used if a NAMESPACE file is
>> present.  Note: Due to registration ## of C functions done in
>> the NAMESPACE file, wireframe (and possibly ## cloud) won't
>> work in this scenario."
>>
>> 	But couldn't quite figure it out.
>> 	Thanks for any help provided.
>> 	Saptarshi
>>
>>
>> Saptarshi Guha | sapsi at pobox.com | http://www.stat.purdue.edu/~sguha
>>
>>
>> 	[[alternative HTML version deleted]]
>>
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>