From ripley at stats.ox.ac.uk  Tue Apr 11 14:52:59 2006
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Tue, 11 Apr 2006 13:52:59 +0100 (BST)
Subject: [Rd] pattern in history
In-Reply-To: <443BA407.30803@free.fr>
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	<Pine.LNX.4.64.0604111302250.4588@gannet.stats.ox.ac.uk>
	<443BA407.30803@free.fr>
Message-ID: <Pine.LNX.4.64.0604111351460.5323@gannet.stats.ox.ac.uk>

On Tue, 11 Apr 2006, Romain Francois wrote:

> Le 11.04.2006 14:12, Prof Brian Ripley a ?crit :
>> That's an interesting suggestion, but
>> 
>> 1) it is not a good idea to change the order of arguments in a function.
> Yes, my mystake. It's because i like to call 'history(something)' directly 
> and not 'history(pattern=something)'.
> I hadn't in mind the possibility to break existing code.
>> 2) is the 'unique' argument useful?  I cannot see it being used if
>> there is no pattern search, nor I do see the merit in showing repeated 
>> lines if I have subselected.
>> 
>> 3) like ls(), testing if 'pattern' were missing or NULL would be a better 
>> idea.
> Right.
> There is also a problem with the order of the calls.
> If I do :
>
>> ls()
>> l <- mean(rnorm(50))
>> ls()
>> history(pattern="^l")
> it prints :
> ls()
> l <- mean(rnorm(50))
>
> when it should print :
> l <- mean(rnorm(50))
> ls()

Well, maybe sorting would be useful here.

BTW, your code also fails (prints NA) if there are not matches.


>
> We can use rev twice (like in history3 below), but is it worth it ?
>
> history3 <-
> function (max.show = 25, reverse = FALSE, pattern, ...)
> {
>  file1 <- tempfile("Rrawhist")
>  savehistory(file1)
>  rawhist <- scan(file1, what = "", quiet = TRUE, sep = "\n")
>  if(!missing(pattern)) rawhist <- rev( unique( rev(rawhist[grep(pattern, 
> rawhist, ...)] ) ) )
>  unlink(file1)
>  nlines <- length(rawhist)
>    inds <- max(1, nlines - max.show):nlines
>  if (reverse)
>      inds <- rev(inds)
>  file2 <- tempfile("hist")
>  write(rawhist[inds], file2)
>  file.show(file2, title = "R History", delete.file = TRUE)
> }
>
>

-- 
Brian D. Ripley,                  ripley at 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


[Rd] pattern in history
Prof Brian Ripley