[Matplotlib-devel] New Axes.lines interface

[Gregor Mönke]

Hello Adrien,

yes of course it's the obvious thing! I should have inspected the
ArtistList object further, thanks a lot for the quick response.

The interface still looks a lot like that of a <list> type of object, the
doc says "these artist lists will likely be replaced by tuples".  Do you
know if that .clear() method will be available for the foreseeable future?!

Cheers,
Gregor

On Wed, Feb 23, 2022 at 11:05 AM vincent.adrien at gmail.com <
vincent.adrien at gmail.com> wrote:

> Hello Gregor,
>
> I am not that much familiar with the very last updates of Matplotlib but
> it looks like the `ax.lines.clear()` method might be worth a try. The
> following snippet of code might achieve the kind of behavior that you are
> looking for (if I understood your needs correctly):
>
> ```python
> import matplotlib.pyplot as plt
>
> def replace_line(ax, xs, ys, **kwargs):
>      # Former method:
>      # there was already a line drawn
>      #if ax.lines:
>      #    ax.lines = []
>      # New method:
>      ax.lines.clear()
>      # (re-)draw
>      ax.plot(xs, ys, **kwargs)
>
>      return ax
>
> if __name__ == "__main__":
>      plt.ion()
>
>      fig, ax = plt.subplots(num="test", clear=True, layout="constrained")
>
>      # Initial line
>      xs0 = [0, 1]
>      ys0 = [0, 1]
>      ax.plot(xs0, ys0, color="tab:red")
>
>      # New line that should replace the previous one(s)
>      xs1 = [1, 0]
>      ys1 = [-1, 2]
>      replace_line(ax, xs1, ys1, color="tab:gray")
> ```
>
> Regards,
> Adrien
>
> Le 23/02/2022 à 10:29, Gregor Mönke a écrit :
> > Hello,
> >
> > I am using interactive matplotlib figures inside a PyQT application (
> https://github.com/tensionhead/pyboat <
> https://github.com/tensionhead/pyboat>), and often I want to re-draw
> lines upon new user input onto an Axis which also has other elements
> (generated by imshow() in my case). For the last years that basically
> worked like this:
> >
> > def draw():
> >      # there was already a line drawn
> >      if ax.lines:
> >          ax.lines = []
> >      # (re-)draw
> >      ax.plot(...)
> >
> > Now (matplotlib 3.5.1) this does not seem to work anymore, as I get an
> Attribute error:
> > AttributeError: can't set attribute 'lines'
> >
> > When I inspect the ax.lines I formerly got a list holding
> `matplotlib.lines.lines2D` objects, now I have a <Axes.ArtistList of 1
> lines>. I looked into the API (
> https://matplotlib.org/devdocs/api/axes_api.html#other <
> https://matplotlib.org/devdocs/api/axes_api.html#other>), and what I got
> from there is that this is a transitional class and I should use this 'as
> it was a tuple already`. I am stuck here now, I tried to `del` the whole
> ax.lines attribute or setting it to an empty tuple but nothing worked.
> >
> > How can I remove a line from an axis without clearing it? Thanks for
> your help!
> >
> > Best,
> > Gregor
> >
> > _______________________________________________
> > Matplotlib-devel mailing list
> > Matplotlib-devel at python.org
> > https://mail.python.org/mailman/listinfo/matplotlib-devel
>
>
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