Re: New warning about inline data and multiplots

[Ethan A M. <me...@uw...>]

On Wed, Dec 3, 2025 at 9:02 AM Dima Kogan <gn...@di...>
wrote:

>
> I just ran the gnuplotlib unit test, and I see lots of warnings with one
> of the tests. The plots are still made, but there's A LOT of console
> chatter now:
>
>   "/tmp/tst.gp" line 17: warning: Reading from '-' inside a multiplot not
> supported; use a datablock instead
>   "/tmp/tst.gp" line 18: warning: Reading from '-' inside a multiplot not
> supported; use a datablock instead
>   "/tmp/tst.gp" line 19: warning: Reading from '-' inside a multiplot not
> supported; use a datablock instead
>   "/tmp/tst.gp" line 20: warning: Reading from '-' inside a multiplot not
> supported; use a datablock instead
>   "/tmp/tst.gp" line 21: warning: Reading from '-' inside a multiplot not
> supported; use a datablock instead
>
> This keeps repeating many times.

The resulting gnuplot script is attached. It clearly shows the warnings.
>
> What isn't supported here?


Exactly what it says.  The current (since version 6.0) implementation of
multiplot does not support placing inline data inside a multiplot block.
This is because the full set of commands inside `set multiplot .... unset
multiplot` is saved for replay during mousing or by a replot command, and
inline data would mess that up badly.


> I've been doing this for years with great
> success, and it appears to still work today.


It does not work today.  What you see is the first execution, with a
warning, while it is reading in the multiplot block. But it does not become
part of the multiplot and the program fails to exit the block cleanly.


> Should I be doing something different?

Yes.

$DATA << EOD
line 1
line 2
...
line N
EOD

set multiplot
plot $DATA with lp
unset multiplot


I use gnuplot constantly, every day. But 99% of my usage is
> either through feedgnuplot or gnuplotlib, both of which use inline data.
> Should those tools be using a datablock? Can they?
>

For use with gnuplot version 6 they should.

The output script, as attached, was also incorrect in that it did not
contain an "unset multiplot" command.  For that matter, I don't think the
script should be using multiplot at all.  Why is it using multiplot?  There
was nothing in the input you showed that requested multiplot.  If "set
multiplot" appears in the output gnuplot script I think that must be a bug
in the program that generated the script.

   Ethan