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Groups > comp.graphics.apps.gnuplot > #3662

Re: skipping values in a data file

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Op vrijdag 2 juni 2017 22:25:31 UTC+2 schreef Ethan A Merritt:
> hugocoolens@gmail.com wrote:
> 
> > Op donderdag 1 juni 2017 23:26:46 UTC+2 schreef Ethan A Merritt:
> >> hugocoolens@gmail.com wrote:
> >> 
> >> > I have a data file with measurements, each measurement has been
> >> > repeated 5 times. However because of a bug in the apparatus software
> >> > the first and the second measurement are always unreliable, therefore I
> >> > want to skip them i.e. I don't want to plot these unreliable data
> >> > points, neither do I want to use them for fitting to a function. This
> >> > is an example: 1
> >> > #unreliable 1.5 #unreliable 3 #reliable
> >> > 3.1 #reliable
> >> > 2.9 #reliable
> >> > #start of next 5 measurements:
> >> > 3 #unreliable
> >> > 3.1 #unreliable
> >> > 3.5 #reliable
> >> > 3.4 #reliable
> >> > 3.6 #reliable
> >> > 
> >> > Can anyone here show me how to do is from within Gnuplot?
> >> > kind regards,
> >> > Hugo
> >> 
> >> If it is always the first two measurements in the file, you can add "skip
> >> 2" to the plot or fit statement:
> >> 
> >>     plot "foo" skip 2 using 0:1
> >> 
> >> However your sample above seems to show that that there are multiple
> >> blocks of data in the file and in each block the first 2 records are bad.
> >> For this you could instead use
> >> 
> >>     plot "foo" every ::2 using 0:1
> >> 
> >> But note that you need a blank line between the data blocks for this to
> >> work (otherwise gnuplot does not know that new block of data is
> >> starting).
> >> 
> >> See "help every"
> >> 
> >> Ethan
> > 
> > Thanks a lot for the reply. Adding an extra blank line is no too
> > difficult. Can I also use the "every" syntax in a fit statement? 
> 
> Yes.  "plot" and "fit" both use exactly the same data input stage.
> 
> > Could you provide an example?
> 
> One of the examples in the fit demo uses "every 5" to select points
>    http://gnuplot.sourceforge.net/demo_cvs/fit.html
> 
> The demo "matrix_every.dem" may also be helpful (it's in the distributed
> demo collection but not one of the on-line examples).
> 
> 	Ethan

Thanks a lot for pointing me to the example
Kind regards,
Hugo

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skipping values in a data file "hugocoolens@gmail.com" <hugocoolens@gmail.com> - 2017-06-01 08:47 -0700
  Re: skipping values in a data file Ethan A Merritt <sfeam@users.sourceforge.net> - 2017-06-01 14:26 -0700
    Re: skipping values in a data file "hugocoolens@gmail.com" <hugocoolens@gmail.com> - 2017-06-02 02:39 -0700
      Re: skipping values in a data file Ethan A Merritt <sfeam@users.sourceforge.net> - 2017-06-02 13:25 -0700
        Re: skipping values in a data file "hugocoolens@gmail.com" <hugocoolens@gmail.com> - 2017-06-03 11:31 -0700

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