[R] Add column index number to str() output

[seth.fore]

I often find it would be very useful when inspecting a data structure using str() to know the column index number in order to rearrange the data in a manner amenable to my purpose. Is there a way to modify the display options of the str() function to add column index? I know this is really a trivial matter but it would increase the utility of the str() function for me and increase the speed with which I can manipulate the data structure. Thanks, 

Seth