Plotting "tail" of data file

Plotting "tail" of data file

Post by sos » Sat, 18 Mar 2000 04:00:00



I am trying to find a way to plot only the last n records of a data file.  I
figured I would ask here before writing something in perl.

I was thinking along the lines of plot the whole data file with xrange
autoscaled, then somehow readback the xmax value from gnuplot and then set
xrange [xmax - delta:] and replot.  It is not obvious to me how to read back
the xmin and xmax values.

Any tips?

--

 
 
 

Plotting "tail" of data file

Post by Hans-Bernhard Broeke » Sat, 18 Mar 2000 04:00:00



> I am trying to find a way to plot only the last n records of a data file.  I
> figured I would ask here before writing something in perl.

A first shot for Unix-like systems might be:

        plot '< tail -20 datafile'

You can't use a variable instead of that '20'.

Quote:> I was thinking along the lines of plot the whole data file with xrange
> autoscaled, then somehow readback the xmax value from gnuplot and then set
> xrange [xmax - delta:] and replot.  It is not obvious to me how to read back
> the xmin and xmax values.

It's not possible in current gnuplot, so stop searching. You can't get
at the autoscaled axis ranges as user-visible variables, currently.
Not without writing out a 'save' file and analysing it with external
tools, at least.

--

Even if all the snow were burnt, ashes would remain.

 
 
 

Plotting "tail" of data file

Post by sos » Sat, 18 Mar 2000 04:00:00


Thanks - the tail pipe worked nicely.

--




> A first shot for Unix-like systems might be:

> plot '< tail -20 datafile'

 
 
 

1. Plotting "missing" data

Does anyone know of a method to indicate missing data in a plot?  Gnuplot
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Example data:

19991010    1
19991011    4
19991012    -
19991013    4

It is of course possible to preprocess the datafile before plotting and add
a third column etc. etc.

/Jens

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