as.character(quote(foo$Bar)[[3]])
[1] "Bar"

Hint: this is nothing to do with data frames ($ applies to lists). $ is an operator, so foo$Bar is a call. quote() stops it being evaluated, [[3]] selects the third of the elements (which are $, foo, Bar) and as.character turns the name into a character string.


On Mon, 3 May 2010, adrien Penac wrote:

Hello,
 I can't find how to get de column name from a data.frame dollar reference.

To make it simple, I'd like to obtain "Bar" from a "foo$Bar" notation.
I've tried col.names(foo$Bar), names(foo$Bar) and so on without sucess.

Regards

Blaise


--
Brian D. Ripley,                  rip...@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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