How to get all legends from a plot?

Question

I have a Plot with 2 or more legends. How can I "get" all the legends to change (for example) the color and linestyle in the legend?

handles, labels = ax.get_legend_handles_labels() only gives me the "first" legend, which I added to the plot with plt.legend(). But I want the others legends too, which I added with plt.gca().add_artist(leg2) How can I do that?

Answer 1

Solution

An alternative: ax.get_legend()

legends = ax.get_legends()

To access the properties of the legends:

legends = ax.get_legend()
dict_legends = {'Legends': dict()}
if not isinstance(legends, list):
    legends = [legends]
for i, legend in enumerate(legends):     
    dict_legend = dict()                                                           
    for j, obj in enumerate(lgnd.get_texts()):
        dict_obj = dict()
        dict_fp = dict()
        text = obj.get_text()
        position = obj.get_position()
        color = obj.get_color()    
        dict_obj.update({'Text': text, 
                         'Position': tuple(position), 
                         'Color': color})
        obj_fp = obj.get_font_properties()
        dict_fp.update({'Font_Name': obj_fp.get_name()})
        fontconfig_pattern = obj_fp.get_fontconfig_pattern()
        font_properties = str.split(fontconfig_pattern,":")
        for fp in font_properties:
            if not (fp.strip()==''):
                key, value = fp.split("=")
                dict_fp.update({str.title(key): value})        
        dict_fp.update({'fontconfig_pattern': fontconfig_pattern})
        dict_obj.update({'Font_Properties': dict_fp})    
        dict_legend.update({'Text_Object_{}'.format(j+1): dict_obj})    
    dict_legends['Legends'].update({'Legend_{}'.format(i): {'Legend_Object': legend, 
                                                            'Contents': dict_legend}})

print(dict_legends)

Configuration:

#  Windows: 10  
#  Python: 3.6  
#  Matplotlib: 2.2.2  

Answer 2

You can get all children from an axes and filter on the legend type with:

legends = [c for c in ax.get_children() if isinstance(c, mpl.legend.Legend)]

But does that work at all? If i add more legends like you mention, i see multiple Legend children, but all are pointing to the same object.

edit:

The axes itself keeps the last legend added, so if you add the previous with .add_artist(), you see multiple different legends:

For example:

fig, ax = plt.subplots()

l1, = ax.plot(x,y, 'k', label='l1')
leg1 = plt.legend([l1],['l1'])

l2, = ax.plot(x,y, 'k', label='l2')
leg2 = plt.legend([l2],['l2'])

ax.add_artist(leg1)

print(ax.get_children())

Returns these objects:

[<matplotlib.axis.XAxis at 0xd0e6eb8>,
 <matplotlib.axis.YAxis at 0xd0ff7b8>,
 <matplotlib.lines.Line2D at 0xd0f73c8>,
 <matplotlib.lines.Line2D at 0xd5c1a58>,
 <matplotlib.legend.Legend at 0xd5c1860>,
 <matplotlib.legend.Legend at 0xd5c4b70>,
 <matplotlib.text.Text at 0xd5b1dd8>,
 <matplotlib.text.Text at 0xd5b1e10>,
 <matplotlib.text.Text at 0xd5b1e48>,
 <matplotlib.patches.Rectangle at 0xd5b1e80>,
 <matplotlib.spines.Spine at 0xd0e6da0>,
 <matplotlib.spines.Spine at 0xd0e6ba8>,
 <matplotlib.spines.Spine at 0xd0e6208>,
 <matplotlib.spines.Spine at 0xd0f10f0>]

It remains to be seen whether this is something you want to do!? You can also store the lines (or other types) yourself separately from the axes.