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Re: How can I do a "grep -v" equivalent in Import[]?

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  • Subject: [mg91806] Re: How can I do a "grep -v" equivalent in Import[]?
  • From: David Bailey <dave at>
  • Date: Mon, 8 Sep 2008 06:10:29 -0400 (EDT)
  • References: <g9t6mq$j8s$>

Jason Ledbetter wrote:
> Folk,
> I have some data that is column formatted with a dual line header every few
> lines; there may also be a variable number of lines between each header
> output. The first line is readily identifiable with say "grep ^FOO", but the
> second line in the header has white space at the beginning.
> So what I need to do is the equivalent of "grep -v" to get rid of the
> headers. My ultimate goal is to create a named List[] variable for each
> "column" in the data, but I need to get rid of the headers.
> Alternatively, I could regex match on the lines I DO want I think.. just
> trying to wrap my head around how to do this in Mathematica.
> For example, "egrep '^[0-9]+' foo.txt" gets me what I need in most shells...
> I'd just like mathematica to do the same on import.
> Do I need to process the import procedurally and dump the data I want into a
> new Table[]?
> I've been able to figure out how to get columnar data out of the import
> using "foo=data[[All,{1}]" and so on (e.g., first column in the data)... I
> just need to pre-filter the headers out.
> I apologize for the junior level of the question. :/
> Thanks!
> -jbl
I think that if you post a TINY example of your input file, together 
with the corresponding output that you wish to obtain, someone will give 
you an answer. As it is, your question is a bit vague.

David Bailey

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