Re: [Rd] Re: tail(<matrix>) column numbers

From: Tony Plate <tplate_at_blackmesacapital.com>
Date: Wed 14 Jul 2004 - 02:05:09 EST

It does seem useful to report original line numbers when tail() is used interactively, but to do this properly, shouldn't it be done in "print" method, rather than by adding row numbers to the data? This is admittedly difficult, because the tail method and the print method are completely separate. One could possibly do this by adding an additional attribute to the object returned by tail (which presumably would be lost on further subsetting), and modifying the relevant print methods to use such information when it is present.

I suspect that the trouble may not be worth the effort in this particular case, but nonetheless it still may be worth thinking about as an example of the general problem of how reconcile what is convenient for interactive use with what is convenient for programming use. (Other examples of which have resulted in permanent defects (IMHO) of the language, such as partial matching for "$" and the default drop=T in subsetting.)

At Monday 01:27 PM 7/12/2004, Patrick Burns wrote:
>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:dmurdoch@pair.com]
>>>Sent: Monday, July 12, 2004 8:06 AM
>>>To: Patrick Burns
>>>Cc: Martin Maechler; Warnes, Gregory R; Prof Brian Ripley; Kevin Wright;
>>>r-devel@stat.math.ethz.ch; Peter Dalgaard
>>>Subject: Re: tail(<matrix>) column numbers
>>>
>>>
>>>On Sun, 11 Jul 2004 12:06:44 +0100, Patrick Burns
>>><pburns@pburns.seanet.com> 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 <pburns@pburns.seanet.com>
>>>>>>>>>> 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.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>>
>>LEGAL NOTICE
>>Unless expressly stated otherwise, this message is confidential and may
>>be privileged. It is intended for the addressee(s) only. Access to this
>>E-mail by anyone else is unauthorized. If you are not an addressee, any
>>disclosure or copying of the contents of this E-mail or any action taken
>>(or not taken) in reliance on it is unauthorized and may be unlawful. If
>>you are not an addressee, please inform the sender immediately.
>>
>>
>>
>
>______________________________________________
>R-devel@stat.math.ethz.ch mailing list
>https://www.stat.math.ethz.ch/mailman/listinfo/r-devel



R-devel@stat.math.ethz.ch mailing list
https://www.stat.math.ethz.ch/mailman/listinfo/r-devel Received on Wed Jul 14 02:10:02 2004

This archive was generated by hypermail 2.1.8 : Wed 03 Nov 2004 - 22:45:02 EST