Basic legend

This section show how to convert your matplotlib legend into interactive legend.

MatplotlibInteractiveLegend function

To activate the interactive matplotlib legend feature, you need to use the MatplotlibInteractiveLegend function. This can be import as follow:

from kivy_matplotlib_widget.uix.legend_widget import MatplotlibInteractiveLegend 

This function require 1 input, the figure instance

MatplotlibInteractiveLegend(fig)

other options are also available with this function

• legend_instance (obj or list) : matplotlib legend instance (optional)
• custom_handlers (list) : list of matplotlib plot instances (line,scatter,bar...)

touch behavior

• single tap : hide or show selected line
• double tap : show all lines if selected line is the only visible line, otherwise it isolate the selected line

Example

based on 'example_legend_matplotlib' example

import matplotlib as mpl
import matplotlib.pyplot as plt
from kivy.metrics import dp

#optimized draw on Agg backend
mpl.rcParams['path.simplify'] = True
mpl.rcParams['path.simplify_threshold'] = 1.0
mpl.rcParams['agg.path.chunksize'] = 1000

font_size_axis_title=dp(13)
font_size_axis_tick=dp(12)        

seaborn_package=True
try:
    import seaborn as sns
except:
    seaborn_package=False

#avoid conflict between mouse provider and touch (very important with touch device)
from kivy.config import Config
Config.set('input', 'mouse', 'mouse,disable_on_activity')

from kivy.lang import Builder
from kivy.app import App
from kivy.core.window import Window
import numpy as np
from random import randint
from kivy_matplotlib_widget.uix.legend_widget import MatplotlibInteractiveLegend  #also register all widgets to kivy register

KV = '''

Screen
    figure_wgt1:figure_wgt1
    figure_wgt2:figure_wgt2
    figure_wgt3:figure_wgt3
    figure_wgt4:figure_wgt4

    BoxLayout:
        orientation:'vertical'
        BoxLayout:
            size_hint_y:0.3
            Button:
                text:"home"
                on_release:app.home()
            ToggleButton:
                group:'touch_mode'
                state:'down'
                text:"pan" 
                on_release:
                    app.set_touch_mode('pan')
                    self.state='down'
            ToggleButton:
                group:'touch_mode'
                text:"zoom box"  
                on_release:
                    app.set_touch_mode('zoombox')
                    self.state='down' 
            ToggleButton:
                group:'touch_mode'
                text:"drag legend"  
                on_release:
                    app.set_touch_mode('drag_legend')
                    self.state='down'                     

        BoxLayout:
            orientation:'vertical'
            BoxLayout:
                MatplotFigure:
                    id:figure_wgt1
                    legend_do_scroll_x:False
                MatplotFigure:
                    id:figure_wgt2
            BoxLayout:
                MatplotFigure:
                    id:figure_wgt3

                MatplotFigure:
                    id:figure_wgt4                  

'''


class Test(App):
    lines = []
    instance_dict = dict()

    def build(self):  
        self.screen=Builder.load_string(KV)
        return self.screen

    def on_start(self, *args):


        fig, ax = plt.subplots(1, 1)
        fig.subplots_adjust(right=0.7)


        for i in range(10):
            x=[randint(0, 9) for p in range(0, 10)]
            x.sort()
            y=[randint(0, 9) for p in range(0, 10)]
            ax.plot(x, y,label='line' + str(i+1))

        self.screen.figure_wgt1.figure = ax.figure
        ax.legend(loc=(1.04, -0.2))

        MatplotlibInteractiveLegend(self.screen.figure_wgt1)

        fig2, ax2 = plt.subplots(1, 1)

        x = [2,4,5,7,6,8,9,11,12,12]
        y = [1,2,3,4,5,6,7,8,9,10]

        sc1 = ax2.scatter(x, y, s=30, color='magenta', alpha=0.7, marker='x', picker=3,label='scatter')
        sc2 = ax2.scatter(np.array(x)+2, np.array(y)+1, s=30, color='r', alpha=0.7, marker='x', picker=3,label='scatter2')
        sc3 = ax2.scatter(np.array(x)+3, np.array(y)+3, s=30, color='k', alpha=0.7, marker='x', picker=3,label='scatter3')
        ax2.legend(loc=4)

        self.screen.figure_wgt2.figure = ax2.figure
        self.screen.figure_wgt2.fast_draw = False #update axis during pan/zoom

        MatplotlibInteractiveLegend(self.screen.figure_wgt2)

        fig3, ax3 = plt.subplots(1, 1)
        x = np.linspace(0, 1)

        # Plot the lines y=x**n for n=1..4.
        for n in range(1, 5):
            ax3.plot(x, x**n, label="n={0}".format(n))
        ax3.legend(loc="upper left",
                    ncol=2, shadow=True, title="Legend", fancybox=True)
        ax3.get_legend().get_title().set_color("red")

        self.screen.figure_wgt3.figure = ax3.figure

        MatplotlibInteractiveLegend(self.screen.figure_wgt3)

        fig4, ax4 = plt.subplots(1, 1)
        if seaborn_package:
            df = sns.load_dataset("penguins")
            sns.barplot(ax=ax4,data=df, x="island", y="body_mass_g", hue="sex")
        self.screen.figure_wgt4.figure = ax4.figure
        self.screen.figure_wgt4.fast_draw = False #update axis during pan/zoom 
        ax4.legend(title="sex",loc=1)                            
        MatplotlibInteractiveLegend(self.screen.figure_wgt4,legend_handles='variante')


    def set_touch_mode(self,mode):
        self.screen.figure_wgt1.touch_mode=mode
        self.screen.figure_wgt2.touch_mode=mode
        self.screen.figure_wgt3.touch_mode=mode
        self.screen.figure_wgt4.touch_mode=mode

    def home(self):
        self.screen.figure_wgt1.home()
        self.screen.figure_wgt2.home()
        self.screen.figure_wgt3.home()
        self.screen.figure_wgt4.home()

Test().run()