R devel - Apr 2006 - pattern in history

Hi,

Sometimes I need to consult the history of commands that are matching a 
regex, so I modified the utils::history function for that purpose. I 
found it useful.

I append the code ( I only added the two lines with #**)

Romain.


history2 <-
function (pattern="", max.show = 25, reverse = FALSE, unique = 
pattern!="", ...)
{
    file1 <- tempfile("Rrawhist")
    savehistory(file1)
    rawhist <- scan(file1, what = "", quiet = TRUE, sep =
"\n")
    rawhist <- rawhist[grep(pattern, rawhist, ...)] #**
    if(unique) rawhist <- unique(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)
}


-- 
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+---------------------------------------------------------------+
| Romain FRANCOIS - http://francoisromain.free.fr               |
| Doctorant INRIA Futurs / EDF                                  |
+---------------------------------------------------------------+

That's an interesting suggestion, but

1) it is not a good idea to change the order of arguments in a function.

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.


On Tue, 11 Apr 2006, Romain Francois wrote:
> Hi,
>
> Sometimes I need to consult the history of commands that are matching a
> regex, so I modified the utils::history function for that purpose. I
> found it useful.
>
> I append the code ( I only added the two lines with #**)
>
> Romain.
>
>
> history2 <-
> function (pattern="", max.show = 25, reverse = FALSE, unique >
pattern!="", ...)
> {
>    file1 <- tempfile("Rrawhist")
>    savehistory(file1)
>    rawhist <- scan(file1, what = "", quiet = TRUE, sep =
"\n")
>    rawhist <- rawhist[grep(pattern, rawhist, ...)] #**
>    if(unique) rawhist <- unique(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)
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