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Re: comments in import files

• To: mathgroup at smc.vnet.net
• Subject: [mg74929] Re: comments in import files
• From: "Szabolcs" <szhorvat at gmail.com>
• Date: Wed, 11 Apr 2007 02:03:50 -0400 (EDT)
• References: <eudd45$sdc$1@smc.vnet.net><eufr25$7rm$1@smc.vnet.net>

This is an old thread, but this might be useful for someone:

I just figured out that you can Import[] from pipes directly, like
this:
Import["!grep -c ^# " <> filename, "Table"]

Szabolcs

http://documents.wolfram.com/mathematica/book/section-1.11.10

On Mar 30, 10:04 am, "beheiger" <beheiger at hotmail.com> wrote:
> Hi Szabolcs,
>
> I took up your approach in the following form:
>
> ImportTableNoComments[filename_] := Module[{tempfilename, res},
>       tempfilename = filename <> "~";
>       Run["grep", "-v", "^#", filename, ">", tempfilename];
>       res = Import[tempfilename, "Table"];
>       DeleteFile[tempfilename];
>       Return[res];
>       ];
>
> Works for me! Thanks,
>
> Andy
>
> "Szabolcs" <szhorvat at gmail.com> schrieb im Newsbeitragnews:eufr25$7rm$1 at smc.vnet.net...
>
> > On Mar 28, 11:39 am, "beheiger" <beheiger at hotmail.com> wrote:
> >> Hi,
>
> >> I would like to know if Mathematica can handlecommentsin import files.
> >> In particular, I would like to add lines ofcommentsto an
> >> <emptyspace>-separated
> >> ASCII table (say, "results.dat") that I produced with other programs.
> >> However,
> >> I can't seem to find anything on how to write thesecommentsin such a
> >> way
> >> that
> >> Mathematica's function, used as
>
> >> Import["results.dat","Table"];
>
> >> does not complain. Help is appreciated.
>
> >> Regards, Andy
>
> > If nobody else posts a better solution (I hope that someone will), you
> > can use the grep program to strip out thecomments, e.g.
> > readTable[filename_] := (Run["grep", "-v", "^#", filename, ">", "c:\
> > \temp\\tmpfile"]; Import["tmpfile", "Table"])
>
> > (This will remove lines starting with #.)
>
> > Of course you can also use Mathematica to read the file line by line
> > and strip out thecomments, but it may be slow with large datasets.