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Re: How to display the value in the n-th column in the 3rd from the last row in the file on a chart?

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TonyG wrote:

> On Thursday, July 19, 2012 10:45:52 AM UTC-4, sfeam wrote:
>> TonyG wrote:
>> 
>> > I assume gnuplot 4.6 does not have a dedicated data file line
>> > addressing mechanism and I would have to use a script.  So, how do I
>> > display a specific value copied from a specific file (generated by a
>> > script) on a chart (using, for example, the 'set label 1
>> sprintf("a = > %3.4f", a) at 500,50' command, a
>> situation described in the title of > my post?
>> 
>> 
>> 
>> Foo = system("tail -3 filename")
>> Labeltext = word(Foo,N)
>> set label 1 Labeltext at some_x, some_y
> 
> At first, I jumped in joy at your suggestion (I was already fiddling with
> the 'system' command), but then, using your syntax on a Windows XP
> system--and similar expressions--I get
> 
> gnuplot> load 'test.gp'
>          "test.gp", line 15: warning: system evaluation not supported by
>          MS-Windows 32 bit

That error message is very misleading.  The actual problem is that the 
executable you are running was built without support for pipes.

I'm not a Windows user so I may have the details wrong, but my understanding
is that older gnuplot versions provided multiple Windows binaries with
different levels of pipe support.  The pipe-capable variants had names like
"pgnuplot.exe" or "wgnuplot_pipes.exe".  More recent versions of gnuplot can be 
built for Windows to provide a unified console-based executable called simply
"gnuplot.exe" that does support pipes.  I suggest you poke around a bit further
to see what options your particular installed version offers.

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How to display the value in the n-th column in the 3rd from the last row in the file on a chart? TonyG <tgozdz@gmail.com> - 2012-07-19 04:07 -0700
  Re: How to display the value in the n-th column in the 3rd from the last row in the file on a chart? sfeam <sfeam@users.sourceforge.net> - 2012-07-19 07:45 -0700
    Re: How to display the value in the n-th column in the 3rd from the last row in the file on a chart? TonyG <tgozdz@gmail.com> - 2012-07-19 08:13 -0700
      Re: How to display the value in the n-th column in the 3rd from the last row in the file on a chart? sfeam <sfeam@users.sourceforge.net> - 2012-07-19 13:32 -0700
        Re: How to display the value in the n-th column in the 3rd from the last row in the file on a chart? TonyG <tgozdz@gmail.com> - 2012-07-21 08:19 -0700

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