[R] easy way to find all extractor functions and the datatypes of what they return

[David Winsemius]

Building on the two prior suggestions ( str() and methods() )  you  
could write a function to get both the named components of an object  
and the functions that work on its class. Using the example lm.D9 in  
the help page for lm:

get_mths_str <- function(obj) c(functs =  
list(methods(class=class(obj))),
                                 components=list(names(lm.D9))
                                )

 > get_mths_str(lm.D9)
$functs
  [1] add1.lm*           addterm.lm*        alias.lm*           
anova.lm           attrassign.lm*
  [6] boxcox.lm*         case.names.lm*     confint.lm*         
cooks.distance.lm* deviance.lm*
[11] dfbeta.lm*         dfbetas.lm*        drop1.lm*           
dropterm.lm*       dummy.coef.lm*
[16] effects.lm*        extractAIC.lm*     family.lm*          
formula.lm*        hatvalues.lm
[21] influence.lm*      kappa.lm           labels.lm*          
logLik.lm*         logtrans.lm*
[26] model.frame.lm     model.matrix.lm    plot.lm             
predict.lm         print.lm
[31] proj.lm*           residuals.lm       rstandard.lm        
rstudent.lm        simulate.lm*
[36] summary.lm         variable.names.lm* vcov.lm*

    Non-visible functions are asterisked

$components
  [1] "coefficients"  "residuals"     "effects"       "rank"           
"fitted.values" "assign"
  [7] "qr"            "df.residual"   "contrasts"     "xlevels"        
"call"          "terms"
[13] "model"

-- 
David

On Oct 10, 2009, at 8:43 AM, Gabor Grothendieck wrote:

> Try this (where "lm" is the class of the lm output):
>
>> methods(class = "lm")
> [1] add1.lm*           alias.lm*          anova.lm            
> case.names.lm*
> [5] confint.lm*        cooks.distance.lm* deviance.lm*        
> dfbeta.lm*
> [9] dfbetas.lm*        drop1.lm*          dummy.coef.lm*      
> effects.lm*
> [13] extractAIC.lm*     family.lm*         formula.lm*         
> hatvalues.lm
> [17] influence.lm*      kappa.lm           labels.lm*          
> logLik.lm*
> [21] model.frame.lm     model.matrix.lm    plot.lm             
> predict.lm
> [25] print.lm           proj.lm*           residuals.lm        
> rstandard.lm
> [29] rstudent.lm        simulate.lm*       summary.lm          
> variable.names.lm*
> [33] vcov.lm*
>
>   Non-visible functions are asterisked
>
>
> On Sat, Oct 10, 2009 at 3:21 AM, Robert Wilkins <robstdev at gmail.com>  
> wrote:
>> Am I asking for too much:
>> for any object that a stat proc returns  ( y <- lm( y~x) ,  
>> etc ) ) , is there
>> a super convenient function like give_all_extractors( y ) that  
>> lists all
>> extractor functions , the datatype returned , and a text descriptor
>> field ("pairwisepval" "lsmean" etc)
>>
>> That would just be so convenient.
>>
>> What are my options for querying an object so that I can quickly  
>> learn
>> the extractor functions to pull out the data and manipulate it?
>> Will the datatypes returned usually be named vectors and named
>> matrices, indiced by categorical values in the data
>> ( "Male" "Female"  "Placebo" "DrugB" etc )? If they are indexed by  
>> 1 ,
>> 2 , 3 , 4 , it's easier to lose track.
>>
>> thanks a bunch in advance
--
>

David Winsemius, MD
Heritage Laboratories
West Hartford, CT