[R] name scoping within dataframe index

[Duncan Murdoch]

On 1/26/2009 1:46 PM, Alexy Khrabrov wrote:
> Every time I have to prefix a dataframe column inside the indexing  
> brackets with the dataframe name, e.g.
> 
> df[df$colname==value,]
> 
> -- I am wondering, why isn't there an R scoping rule that search  
> starts with the dataframe names, as if we'd said
> 
> with(df, df[colname==value,])
> 
> -- wouldn't that be a reasonable default to prepend to the name search  
> path?

If you did that, it would be quite difficult to get at a "colname" 
variable that *isn't* the column of df.  It would be something like

  df[get("colname", parent.frame()) == value,]

So just use subset(), or with(), or type the extra 3 chars.

Duncan