Customize legend in object interface

[Auerilas]

Hi,
Is it possible to customize the legend of an object interface? Right now I'm trying a variety of ways to access it via the matplotlib axes and figures, but nothing changes the legend.

g = (so.Plot(ange_surv, x='Week ', y='GWC',
color='Treatment ')
.add(so.Dot(alpha = 0.35), so.Jitter(), so.Dodge())
.add(so.Range(linewidth=2), so.Est(errorbar=('se', 1)), so.Dodge())
.add(so.Dot(pointsize=12), so.Agg(), so.Dodge())
.label(x='Week of Experiment', y='GWC')
.theme(sns_theme)
)
f = plt.figure()
res = g.on(f).plot()
ax = f.axes[0]
ax.legend(ncols=2, loc=2, bbox_to_anchor=(1.01, 1.01))
plt.show()

And the matplotlib rcparams don't allow for fine-tuning.

[thuiop]

See issue #2994 but tl;dr, legends are a pain and matplotlib does not really have an interface for modifying them.

I currently use this function for moving the legend around :

def move_legend_fig_to_ax(fig, ax, loc, bbox_to_anchor=None, **kwargs):
    if fig.legends:
        old_legend = fig.legends[-1]
    else:
        raise ValueError("Figure has no legend attached.")

    old_boxes = old_legend.get_children()[0].get_children()

    legend_kws = inspect.signature(mpl.legend.Legend).parameters
    props = {
        k: v for k, v in old_legend.properties().items() if k in legend_kws
    }

    props.pop("bbox_to_anchor")
    title = props.pop("title")
    if "title" in kwargs:
        title.set_text(kwargs.pop("title"))
    title_kwargs = {k: v for k, v in kwargs.items() if k.startswith("title_")}
    for key, val in title_kwargs.items():
        title.set(**{key[6:]: val})
        kwargs.pop(key)
    kwargs.setdefault("frameon", old_legend.legendPatch.get_visible())

    # Remove the old legend and create the new one
    props.update(kwargs)
    fig.legends = []
    new_legend = ax.legend(
        [], [], loc=loc, bbox_to_anchor=bbox_to_anchor, **props
    )
    new_legend.get_children()[0].get_children().extend(old_boxes)

(it is custom made but largely inspired by move_legend)

[Auerilas]

I understand. It's unfortunate that mpl makes it so difficult, because modifying the legend is the one thing I desperately need to do. Otherwise, the plot object interface is amazing.

…

On Tue, Feb 7, 2023 at 6:59 AM thuiop ***@***.***> wrote: See issue #2994 <#2994> but tl;dr, legends are a pain and matplotlib does not really have an interface for modifying them. I currently use this function for moving the legend around : def move_legend_fig_to_ax(fig, ax, loc, bbox_to_anchor=None, **kwargs): if fig.legends: old_legend = fig.legends[-1] else: raise ValueError("Figure has no legend attached.") old_boxes = old_legend.get_children()[0].get_children() legend_kws = inspect.signature(mpl.legend.Legend).parameters props = { k: v for k, v in old_legend.properties().items() if k in legend_kws } props.pop("bbox_to_anchor") title = props.pop("title") if "title" in kwargs: title.set_text(kwargs.pop("title")) title_kwargs = {k: v for k, v in kwargs.items() if k.startswith("title_")} for key, val in title_kwargs.items(): title.set(**{key[6:]: val}) kwargs.pop(key) kwargs.setdefault("frameon", old_legend.legendPatch.get_visible()) # Remove the old legend and create the new one props.update(kwargs) fig.legends = [] new_legend = ax.legend( [], [], loc=loc, bbox_to_anchor=bbox_to_anchor, **props ) new_legend.get_children()[0].get_children().extend(old_boxes) (it is custom made but largely inspired by move_legend <https://seaborn.pydata.org/generated/seaborn.move_legend.html>) — Reply to this email directly, view it on GitHub <#3247 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACHQESS3B2GMMZ2J5FTXNXDWWJBLTANCNFSM6AAAAAAUTOI3RE> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[mwaskom]

Yep, very aware of the need for this, but want to get it right. Legends are tricky, they're basically their own plot within a plot. Going to close as a duplicate of #2994 (but thanks @thuiop for that handy recipe).