[R] more structure than 'str'?

Spencer Graves spencer.graves at pdf.com
Mon Dec 17 03:44:53 CET 2007

      How can I see more of the structure than displayed by 'str'?  
Consider the following: 

tstDF <- data.frame(a=1, row.names='b')
 > str(tstDF)
'data.frame':   1 obs. of  1 variable:
 $ a: num 1

      The object 'tstDF' has row.names, but I have to suspect they are 
there -- AND know a function like 'row.names' or 'dimnames' -- to see 

      I've found 'str' extremely valuable for understanding and 
explaining to others the internal structure of an R object.   In many 
cases, it has helped me find fairly simple ways to do things with R 
objects that might have been much more difficult and perhaps infeasible 
without 'str' -- and without access to the right expert, who may not be 
available in the time I have to solve a particular problem. 

      Thanks again to Martin Maechler, who wrote 'str', and to everyone 
else who has replied to questions from me over the years. 

      Best Wishes,
      Spencer Graves
p.s.  'methods(class="data.frame")' would help in this example.  
However, 'methods' won't always find all available and recommended 
extractor functions.  For example, 'methods(class="lm")' was not able to 
find 'AIC' for me just now.

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