[SOLVED] gnuplot - plotting multiple files some may have no data

Quakeboy02 · 10-08-2013, 09:58 PM

Subject says it. I have multiple files I need to plot overlaying each other. Some of them may be empty. Is there a way to have it ignore the "Skipping data file with no valid points" error and just continue plotting? Here is my plot statement. the 9682 and/or 967E data files may be empty, but I need to see any data in either that is there. I don't know ahead of time which, if either, will have data.

Code:

plot  './fll.dat' using 1:14 axes x1y2 title 'Integrator Err' with points \ 
        pt 5 ps .3 lc rgb "green", \ 
      './fll.dat' using 1:5 axes x1y1 title 'DAC' with lines \
         lw 1 lc rgb "blue", \
       './integ.dat' using 1:5 axes x1y1 title 'Integrator Updates' \
        with points pt 5 ps .2 lw 1 lc rgb "red", \
       './9682.dat' using 1:5 axes x1y1 title '9682 Sample' \
        with points pt 5 ps .2 lw 1 lc rgb "black", \
       './967E.dat' using 1:5 axes x1y1 title '967E Sample' \
         with points pt 5 ps .2 lw 1 lc rgb "purple"

Quakeboy02 · 10-09-2013, 12:59 PM

I figured out a solution so I thought I'd post it. Its seems overly complicated for what should be a simple switch in the gnuplot program. This creates two strings, $F967E and $F9682 which are appended to the part of the plot statement that always has data. If the file is empty, then the string is null for that file and no attempt is made to plot it.

In the scripting section of the script I added this:

Code:

if [ `stat --print="%s" 967E.dat` -ne 0 ]
then
   F967E=" ,\
         '967E.dat' using 1:5 axes x1y1 title '967E Sample'\
          with points pt 5 ps .2 lw 1 lc rgb \"purple\""
fi

if [ `stat --print="%s" 9682.dat` -ne 0 ]
then
   F9682=" ,\
         '9682.dat' using 1:5 axes x1y1 title '9682 Sample'\
         with points pt 5 ps .2 lw 1 lc rgb \"black\""
fi

In the gnuplot section of the script I changed this:

Code:

plot  './fll.dat' using 1:14 axes x1y2 title 'Integrator Err' with points \
        pt 5 ps .3 lc rgb "green", \
      './fll.dat' using 1:5 axes x1y1 title 'DAC' with lines \
         lw 1 lc rgb "blue", \
       './integ.dat' using 1:5 axes x1y1 title 'Integrator Updates' \
         with points pt 5 ps .2 lw 1 lc rgb "red" $F967E $F9682

bigrigdriver · 10-09-2013, 12:59 PM

Try a google search for "gnuplot empty data points". The first three or four returns should answer your question.

The consensus seems to be: for empty data points, substitute non-numerical data such as a dash.

Quakeboy02 · 10-09-2013, 01:01 PM

Hi bigrigdriver. Thanks for the response. I had done many searches and found no answers. But as I was looking at my post after I made it, I realized the empty string trick would work, and so here it is, above.