[R] name scoping within dataframe index

Alexy Khrabrov deliverable at gmail.com
Mon Jan 26 20:20:55 CET 2009


On Jan 26, 2009, at 2:12 PM, Duncan Murdoch wrote:
>>> df[get("colname", parent.frame()) == value,]
>> Actually, what I propose is  a special search rule which simply  
>> looks  at the enclosing dataframe.name[...] outside the brackets  
>> and looks up  the columns first.
>
> Yes, I understood that, and I explained why it would be a bad idea.

Well this is the case in all programming languages with scoping where  
inner-scope variables override the outer ones.  Usually it's solved  
with prefixing with the outer scope, outercsope.name or  
outerscope::name or so.  So it only underscores the need to improve  
scoping access in R.

Dataframe column names belong to the dataframe object and the natural  
thing would be to enable easy access to naming; you'd need to apply an  
extra effort to access an overridden unrelated external variable.   
Again, just an analogy from other programming languages.

Cheers,
Alexy



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