Gnuplot internal error : STRING operator applied to undefined or non-STRING variable

Question

I was trying to plot a 18 line graph with gnuplot, so I used the code below and it shows the non-string variable error.

plot for [num = 4560 : 5072 : 64] \
    "graph_".num.".dat" using 1:4 with lines lw 2 title "".num.".fast", \
    "graph_".num.".dat" using 1:2 with lines lw 2 title "".num.".slow"
replot

But when I only use one, it works perfectly. I thought it could be because of a maximum number of lines in the legend or something. How can I plot these 18 lines in the same graph?

Sugar G. García · Accepted Answer · 2021-02-22 22:19:12Z

1

Ok, I found the problem, you have to set the loop twice, because they are different plots.

plot for [num = 4560 : 5072 : 64] \
   "graphs/tam_".num.".dat" using 1:4 with lines lw 2 title "".num.".fast", \
     for [num = 4560 : 5072 : 64] \
    "graphs/tam_".num.".dat" using 1:2 with lines lw 2 title "".num.".slow"
replot

edited Feb 22, 2021 at 22:19

answered Nov 27, 2020 at 15:44

Sugar G. García

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