From murdoch at stats.uwo.ca  Sat Dec  4 15:17:26 2004
From: murdoch at stats.uwo.ca (Duncan Murdoch)
Date: Sat Dec  4 15:16:39 2004
Subject: [Rd] write.table inconsistency (PR#7403)
In-Reply-To: <16817.45803.674748.804800@gargle.gargle.HOWL>
References: <20041204005526.3C298F18D@slim.kubism.ku.dk>
	<16817.45803.674748.804800@gargle.gargle.HOWL>
Message-ID: <32h3r0h4hkapvs2htc73ga72712ten2bcf@4ax.com>

On Sat, 4 Dec 2004 13:51:55 +0100, Martin Maechler
<maechler@stat.math.ethz.ch> wrote:

>>>>>> "Duncan" == Duncan Murdoch <murdoch@stats.uwo.ca>
>>>>>>     on Sat,  4 Dec 2004 01:55:26 +0100 (CET) writes:
>
>    Duncan> There's an as.matrix() call in write.table that means the formatting
>    Duncan> of numeric columns changes depending on whether there are any
>    Duncan> non-numeric columns in the table or not.  
>
>yes, I think I had seen this (a while ago in the source code)
>and then wondered if one shouldn't have used
>   data.matrix()  instead of  as.matrix()   
>- something I actually do advocate more generally, as "good
>programming style".  It also does solve the problem in the
>example here -- HOWEVER, the lines *before* as.matrix() have
>
>    ## as.matrix might turn integer or numeric columns into a complex matrix
>    cmplx <- sapply(x, is.complex)
>    if(any(cmplx) && !all(cmplx)) x[cmplx] <- lapply(x[cmplx], as.character)
>    x <- as.matrix(x)
>
>which makes you see that  write.table(.) should also work when
>the data frame has complex variables {or some other kinds of
>non-numeric as you've said above} -- something which
>data.matrix() can't handle....
>As soon as you have a complex or a character variable (together
>with others) in your data.frame,  as.matrix() will have to
>return "character" and apply format() to the numeric variables, as well...
>
>So, to make this consistent in your sense, i.e. formatting of a
>column shouldn't depend on the presence of other columns, we
>can't use as.matrix() nor data.matrix() but have to basically
>replicate an altered version of as.matrix inside write.table.
>
>I propose to do this, but expose the altered version as
>something like
>   as.charMatrix(.)
>
>and replace the 4 lines {of code in write.table()} above by the
>single line
>   as.charMatrix(x)

That sounds good.  Which version of the formatting would you choose,
leading spaces or not?  My preference would be to leave off the
leading spaces, in the belief that write.table is usually used for
data storage rather than data display, but it is sometimes used for
data display (e.g. in utils::upgrade.packageStatus, which would not be
affected by your choice).

Duncan Murdoch


[Rd] write.table inconsistency (PR#7403)
Duncan Murdoch