I give it my vote as well.
Pat
Warnes, Gregory R wrote:
I also vote for the 'helpful' addition on row numbers based on the original
matrix when no row names are present, with an optional argument to prevent
this behaviour.
-G
-----Original Message-----
From: Duncan Murdoch [mailto:[EMAIL PROTECTED]
Sent: Monday, July 12, 2004 8:06 AM
To: Patrick Burns
Cc: Martin Maechler; Warnes, Gregory R; Prof Brian Ripley;
Kevin Wright;
[EMAIL PROTECTED]; Peter Dalgaard
Subject: Re: tail(<matrix>) column numbers
On Sun, 11 Jul 2004 12:06:44 +0100, Patrick Burns
<[EMAIL PROTECTED]> wrote :
I disagree with Martin's assertion that "tail" is not useful
for programming. It has a few features relative to the
do-it-yourself approach:
Me too actually. I think tail() has two uses, interactive and
programmatic. I think it would be better for interactive use if
the row names were added, and only slightly worse for programmatic use
if an option were given to turn them off.
In interactive use, I find it unhelpful to be told that something is
in row 3 when it's really in row 47.
Duncan Murdoch
*) It compactly makes the intention clear.
*) It automatically handles cases where there may be
either a vector or a matrix.
*) It handles cases where there is less data than is being
sought (which may or may not be a good thing).
"tail" of functions is what is definitely intended for interactive
use.
Pat
Martin Maechler wrote:
"PatBurns" == Patrick Burns <[EMAIL PROTECTED]>
on Tue, 27 Jan 2004 14:20:30 +0000 writes:
[more than half a year ago]
PatBurns> Duncan Murdoch wrote:
.............
DM> One other one I'll look at:
DM>
DM> If a matrix doesn't have row names, I might add names
DM> like '[nn,]' to it, so I get results like
R> x <- matrix(1:100,ncol=2)
R> tail(x)
Rout> [,1] [,2]
Rout> [45,] 45 95
Rout> [46,] 46 96
Rout> [47,] 47 97
Rout> [48,] 48 98
Rout> [49,] 49 99
Rout> [50,] 50 100
Rout>
DM> instead of the current
R> tail(x)
Rout> [,1] [,2]
Rout> [1,] 45 95
Rout> [2,] 46 96
Rout> [3,] 47 97
Rout> [4,] 48 98
Rout> [5,] 49 99
Rout> [6,] 50 100
DM> I just want to be careful that this doesn't mess up
DM> something else.
DM>
DM> Duncan Murdoch
PatBurns> I think this could be being too "helpful". Using
PatBurns> tail on a matrix may often be done in a program so
PatBurns> I think leaving things as they come is the best
PatBurns> policy.
I tend to disagree, and would like to have us think about it
again:
1) Duncan's proposal was to only add row names *when*
there are none.
2) Pat is write that tail() for matrices maybe used not
only interactively
and help(tail)'s "Value:" section encourages this to
some extent.
However, how can adding column names to such a
matrix-tail be harmful?
Well, only in the case where the tail is quite large, the
added dimnames add unneeded memory and other overhead when
dealing with that matrix.
But I think, programmers/users caring about efficient code
wouldn't use tail(<matrix>) in their function code, would they?
In conclusion, I'd still argue for following Duncan's proposal,
maybe adding a \note{.} to head.Rd stating that these functions
were meant for interactive use, and for "programming", we'd
rather recommend the direct (n-k+1):n indexing.
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