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

[Werner L. <wer...@pe...>]

I use plot-commands ext6ending over 200 - 300 lines, never had a problem.

Just my 5 Cents.


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On 29 Mar 2026, at 11:49, Bjorn Buckwalter <bjo...@gm...> wrote:

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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