Re: [Gnuplot-info] Managing long/complicated plot commands?

[Bjorn B. <bjo...@gm...>]

Hi Hernán and thanks for the suggestion.

Do I understand correctly that you propose using a script written in
another language to generate the gnuplot script (the "configuration file")?
This may indeed be a good option, to generate a verbose and repetitive but
straight-forward gnuplot script.

I will admit that I was rather happy to have my plotting infrastructure
being only self-contained gnuplot code, but I will seriously consider this.

Thanks,
Bjorn





On Sun, Mar 29, 2026 at 12:23 PM Hernán De Angelis <
var...@gm...> wrote:

> You may already had this suggestion, as in using variables, but consider
> that given the length and complexity of your command, it is perhaps a
> better idea to use a script to do all steps from building your set of
> plot instructions, writing them to a configuration file, and then
> running the gnuplot command. I do this all the time to a good effect.
>
> /H.
>
> Den 2026-03-29 kl. 11:49, skrev Bjorn Buckwalter:
> > Thanks Jesper and Philpp. Jespers suggestion with variables can likely
> help
> > – I will try it!
> >
> > FYI here is an example plot command that fails:
> >
> > ```
> >    plot \
> >      'world_110m.txt' using (lon($1)):(filter_lat($2)) with lines
> linecolor
> > "gray" notitle , \
> >      lat(0) with lines black dashtype 2 title "Equator" , \
> >      lat(66.6) with lines black dashtype 5 title "Arctic/Antarctic
> circle", \
> >      lat(-66.6) with lines black dashtype 5 notitle , \
> >      for [orbit in orbits] \
> >        'data/Report'.orbit.'.txt' using (lon($7)):(filter_lat($6)) \
> >          with lines linecolor rgb next_color_t(n, 'cc') notitle, \
> >      for [orbit in orbits] \
> >        'data/Report'.orbit.'.txt' using (lon($7)):($3 == 2030 ?
> > filter_lat($6) : NaN) \
> >          with lines linecolor rgb next_color(n) title orbit, \
> >      lat(lat1) black notitle  # edge of plot
> > ```
> >
> > There is A LOT going on there with various custom functions, etc. I tried
> > to make a minimal and “dependency-free” example but failed to reproduce
> the
> > behavior. I could maybe try harder.
> >
> > Here is in any case the error from gnuplot. The command has been
> > concatenated at all baskslashes except the last:
> >
> > ```
> >    plot     'world_110m.txt' using (lon($1)):(filter_lat($2)) with lines
> > linecolor "gray" notitle ,     lat(0) with lines black dashtype 2 title
> > "Equator" ,     lat(66.6) with lines black dashtype 5 title
> > "Arctic/Antarctic circle",     lat(-66.6) with lines black dashtype 5
> > notitle ,     for [orbit in orbits]       'data/Report'.orbit.'.txt'
> using
> > (lon($7)):(filter_lat($6))         with lines linecolor rgb
> next_color_t(n,
> > 'cc') notitle,     for [orbit in orbits]       'data/Report'.orbit.'.txt'
> > using (lon($7)):($3 == 2030 ? filter_lat($6) : NaN)         with lines
> > linecolor rgb next_color(n) title orbit, \    lat(lat1) black notitle  #
> > edge of plot
> >
> >
> >
> >
> >
> >
> >
> >
> >     ^
> > "$plot_polar" line 15: invalid character \
> > ```
> >
> > There is nothing wrong with the backslash (no trailing spaces, etc.).
> >
> > If I change it as so (just shortening style definitions) it works:
> >
> > ```
> >    set style data lines
> >    plot \
> >      'world_110m.txt' using (lon($1)):(filter_lat($2)) lc "gray" notitle
> , \
> >      lat(0) black dt 2 title "Equator" , \
> >      lat(66.6) black dt 5 title "Arctic/Antarctic circle", \
> >      lat(-66.6) black dt 5 notitle , \
> >      for [orbit in orbits] \
> >        'data/Report'.orbit.'.txt' using (lon($7)):(filter_lat($6)) \
> >          lc rgb next_color_t(n, 'cc') notitle, \
> >      for [orbit in orbits] \
> >        'data/Report'.orbit.'.txt' using (lon($7)):($3 == 2030 ?
> > filter_lat($6) : NaN) \
> >          lc rgb next_color(n) title orbit, \
> >      lat(lat1) black notitle  # edge of plot
> > ```
> >
> > All I did was remove `with lines` (using `set style data lines` instead
> and
> > replace `linecolor` and `dashtype` with `lc` and `dt`, respectively. This
> > is why I say it seems to be somehow related to the length/number of
> > characters of a command.
> >
> > Thanks,
> > Bjorn
> >
> >
> > On Sun, Mar 29, 2026 at 5:28 AM Philipp K. Janert<ph...@ja...>
> wrote:
> >
> >> On Sat, 28 Mar 2026 22:13:40 +0100
> >> Bjorn Buckwalter<bjo...@gm...> wrote:
> >>
> >>> HI all,
> >> How long (in characters) are the command lines that
> >> you are using? Mine frequently run long, and it has
> >> never been a problem.
> >>
> >> Is it possible that you have problems with embedded
> >> newlines, or that something goes awry if your command
> >> line runs into a new line in your terminal?
> >>
> >> Best,
> >>
> >>                  Ph.
> >>
> >>> I rather often run into a problem of my plot commands being too long,
> >>> typically resulting in a not-very-helpful error message such as:
> >>>
> >>> "$plot_polar" line 21: invalid character \
> >>>
> >>> It took a lot of head scratching to realize the root of the problem. I
> >>> assume there are strong reasons for both the limitation on command
> >>> length and the poor error message.
> >>>
> >>> I cannot be the only one running into this problem. The situation
> >>> being what it is, what are the rest of you doing to manage when you
> >>> run up against this limit? Replacing `linecolor` with `lc`, etc, will
> >>> only get me so far and at the expense of readability.
> >>>
> >>> Many thanks,
> >>> Bjorn
> >>>
> >>> _______________________________________________
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> >>
> >>
> >> --
> >>
> >> Philipp K. Janert
> >> www.janert.me
> >>
> >>
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