[R] read.table: check.names arg - feature request

Tony Plate tplate at blackmesacapital.com
Thu Sep 4 19:50:47 CEST 2003

If you have a special need, it probably far more time effective on your 
part to write a special function rather than attempt to convince the very 
busy R developers that they should add a new feature to a very old function 
(is this a better use of their time than, say, fixing long identified bugs 
that have not yet been fixed for lack of time?).

You should be able to do something like:

my.read.table <- function(..., header=T, comment.char="", check.names=F) {
      x <- read.table(..., header=header, comment.char=comment.char, 
      colnames(x)[1] <- gsub("#", "", colnames(x)[1])

And with your example on my clipboard:

 > readLines("clipboard", -1)
[1] "#key    value" "foo     1.2"   "boo     1.3"
 > read.table("clipboard", header=T, comment.char="", check.names=F)
   #key value
1  foo   1.2
2  boo   1.3
 > my.read.table("clipboard")
   key value
1 foo   1.2
2 boo   1.3

hope this helps,

Tony Plate

At Thursday 10:00 AM 9/4/2003 -0700, Vadim Ogranovich wrote:
>I admit I should have been more clear in my original posting. Let me try 
>again (and I do know that by deafulat read.table discards everything after 
>'#' which is why I use comment.char="", my bad not to mention this).
>Here is a typical example of my data file:
>#key    value
>foo     1.2
>boo     1.3
>As you see the header line begins with '#' and then lists the column 
>names, however make.names will convert the raw names  c("#key", "value") 
>to c(".key", "value") while I need c("key", "value"), i.e. no dot before 
>key. So I am asking to give us a hook to specify the function that will 
>handle this situation.
>I am not sure I understand how having this hook can result in an invalid 
>data frame? It can return invalid names, but check.names=FALSE can too.
>-----Original Message-----
>From: Martin Maechler [mailto:maechler at stat.math.ethz.ch]
>Sent: Thursday, September 04, 2003 1:28 AM
>To: Vadim Ogranovich
>Cc: R-Help (E-mail)
>Subject: Re: [R] read.table: check.names arg - feature request
> >>>>> "Vadim" == Vadim Ogranovich <vograno at evafunds.com>
> >>>>>     on Wed, 3 Sep 2003 14:29:25 -0700 writes:
>     Vadim> Hi, I thought it would be convenient if the
>     Vadim> check.names argument to read.table, which currently
>     Vadim> can only be TRUE/FALSE, could take a function value
>     Vadim> as well. If the function is supplied it should be
>     Vadim> used instead of the default make.names.
>One could, but it's not necessary in your case (see below), and
>it's a potential pit to fall in..  We want read.table() to
>return valid  data frames.
>     Vadim> Here is an example where it can come in handy. I tend
>     Vadim> to keep my data in coma-separated files with a header
>     Vadim> line. The header line is prefixed with a comment sign
>     Vadim> '#' to simplify identification of these lines. Now
>     Vadim> when I read.table the files the '#' is converted to
>     Vadim> '.' while I want it to be discarded.
>Hmm, are you using a very old version of R,
>or haven't you seen the `comment.char = "#"' argument of
>Reading "?read.table", also note the note about
>`blank.lines.skip' , and then realize that the default for
>blank.lines.skip is  ` !fill ' and that `fill = TRUE' for all
>the read.csv* and read.delim* incantation of read.table().
>In sum, it's very easy to use current read.table() for your
>     Vadim> P.S. I don't know if r-help is the right place for
>     Vadim> feature requests. If it's not please let me know
>     Vadim> where the right one is.
>Since your proposal can be interpreted as "How do I use
>read.table() when my file has comment lines?",
>r-help has been very appropriate.
>Otherwise, and particularly if the proposal is more technical,
>R-devel would be better suited.
>Martin Maechler <maechler at stat.math.ethz.ch>    http://stat.ethz.ch/~maechler/
>Seminar fuer Statistik, ETH-Zentrum  LEO C16    Leonhardstr. 27
>ETH (Federal Inst. Technology)  8092 Zurich     SWITZERLAND
>phone: x-41-1-632-3408          fax: ...-1228                   <><
>R-help at stat.math.ethz.ch mailing list

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