From hin-tak.leung at cimr.cam.ac.uk  Mon Dec 12 13:45:11 2005
From: hin-tak.leung at cimr.cam.ac.uk (Hin-Tak Leung)
Date: Mon, 12 Dec 2005 12:45:11 +0000
Subject: [Rd] [R] data.frame() size
In-Reply-To: <Pine.LNX.4.61.0512121134080.17506@gannet.stats>
References: <78166BFC5165D811AA0400065BF0324BF07B36@wisconsin.concordia>
	<Pine.LNX.4.61.0512121134080.17506@gannet.stats>
Message-ID: <439D70D7.1070705@cimr.cam.ac.uk>

Prof Brian Ripley wrote:
> Data frames have unique row names *by definition* (White Book p.57).

Yes - I happened to have the White Book on my desk (not mine...)
- indeed, the first sentence on page 57 is (quote verbatim, the
"never" is in italic in the book, which I have added the "*" before and 
after):

    If all else fails, the row names are just the row numbers. They
    are *never* null and must be unique.

So patching data.frame.R is quite wrong. However, the rowname/colname
overhead is definitely an issue for processing of large data sets,
both for speed and amount of memory consumed. So it is probably best
to extend the data.frame class and call it something else instead,
for those who needs to go that route.

(What I am doing is already called a different name so it isn't
affected by this argument).

Hin-Tak



[Rd] [R] data.frame() size
Hin-Tak Leung