Hiding lines after showing a pyplot figure

Question

I\'m using pyplot to display a line graph of up to 30 lines. I would like to add a way to quickly show and hide individual lines on the graph. Pyplot does have a menu wher

Answer 1

Thanks for the post! I extended the class above such that it can handle multiple legends - such as for example if you are using subplots. (I am sharing it here since i could not find any other example somewhere else... and it might be handy for someone else...)

    class InteractiveLegend(object):
 def __init__(self):

  self.legends = []
  self.figures = []
  self.lookup_artists = []
  self.lookup_handles = []

  self.host = socket.gethostname()

def add_legends(self, legend):

  self.legends.append(legend)

def init_legends(self):

    for legend in self.legends:

      self.figures.append(legend.axes.figure)

      lookup_artist, lookup_handle = self._build_lookups(legend)

      #print("init", type(lookup))

      self.lookup_artists.append(lookup_artist)
      self.lookup_handles.append(lookup_handle)

    self._setup_connections()
    self.update()

def _setup_connections(self):

    for legend in self.legends:
      for artist in legend.texts + legend.legendHandles:
          artist.set_picker(10) # 10 points tolerance

    for figs in self.figures:
      figs.canvas.mpl_connect('pick_event', self.on_pick)
      figs.canvas.mpl_connect('button_press_event', self.on_click)

def _build_lookups(self, legend):
    labels = [t.get_text() for t in legend.texts]

    handles = legend.legendHandles
    label2handle = dict(zip(labels, handles))
    handle2text = dict(zip(handles, legend.texts))

    lookup_artist = {}
    lookup_handle = {}
    for artist in legend.axes.get_children():
        if artist.get_label() in labels:
            handle = label2handle[artist.get_label()]
            lookup_handle[artist] = handle
            lookup_artist[handle] = artist
            lookup_artist[handle2text[handle]] = artist

    lookup_handle.update(zip(handles, handles))
    lookup_handle.update(zip(legend.texts, handles))

    #print("build", type(lookup_handle))

    return lookup_artist, lookup_handle

def on_pick(self, event):

    #print event.artist
    handle = event.artist
    for lookup_artist in self.lookup_artists:
      if handle in lookup_artist:
          artist = lookup_artist[handle]
          artist.set_visible(not artist.get_visible())
          self.update()

def on_click(self, event):
    if event.button == 3:
        visible = False
    elif event.button == 2:
        visible = True
    else:
        return

    for lookup_artist in self.lookup_artists:
      for artist in lookup_artist.values():
          artist.set_visible(visible)
    self.update()

def update(self):
    for idx, lookup_artist in enumerate(self.lookup_artists):
      for artist in lookup_artist.values():
          handle = self.lookup_handles[idx][artist]
          if artist.get_visible():
              handle.set_visible(True)
          else:
              handle.set_visible(False)
      self.figures[idx].canvas.draw()

def show(self):
    plt.show()

use it as follow:

leg1 = ax1.legend(loc='upper left', bbox_to_anchor=(1.05, 1), ncol=2, borderaxespad=0)
leg2 = ax2.legend(loc='upper left', bbox_to_anchor=(1.05, 1), ncol=2, borderaxespad=0)
fig.subplots_adjust(right=0.7)

interactive_legend = InteractiveLegend()

interactive_legend.add_legends(leg1)
interactive_legend.add_legends(leg2)
interactive_legend.init_legends()
interactive_legend.show()

Answer 2

If you'd like, you can hook up a callback to the legend that will show/hide lines when they're clicked. There's a simple example here: http://matplotlib.org/examples/event_handling/legend_picking.html

Here's a "fancier" example that should work without needing to manually specify the relationship of the lines and legend markers (Also has a few more features).

(Updated version in August 2019, as a response to repeated reports about this not working correctly; now it should! For the old version see version history)

import numpy as np
import matplotlib.pyplot as plt


def main():
    x = np.arange(10)
    fig, ax = plt.subplots()
    for i in range(1, 31):
        ax.plot(x, i * x, label=r'$y={}x$'.format(i))

    ax.legend(loc='upper left', bbox_to_anchor=(1.05, 1),
              ncol=2, borderaxespad=0)
    fig.subplots_adjust(right=0.55)
    fig.suptitle('Right-click to hide all\nMiddle-click to show all',
                 va='top', size='large')

    leg = interactive_legend()
    return fig, ax, leg

def interactive_legend(ax=None):
    if ax is None:
        ax = plt.gca()
    if ax.legend_ is None:
        ax.legend()

    return InteractiveLegend(ax.get_legend())

class InteractiveLegend(object):
    def __init__(self, legend):
        self.legend = legend
        self.fig = legend.axes.figure

        self.lookup_artist, self.lookup_handle = self._build_lookups(legend)
        self._setup_connections()

        self.update()

    def _setup_connections(self):
        for artist in self.legend.texts + self.legend.legendHandles:
            artist.set_picker(10) # 10 points tolerance

        self.fig.canvas.mpl_connect('pick_event', self.on_pick)
        self.fig.canvas.mpl_connect('button_press_event', self.on_click)

    def _build_lookups(self, legend):
        labels = [t.get_text() for t in legend.texts]
        handles = legend.legendHandles
        label2handle = dict(zip(labels, handles))
        handle2text = dict(zip(handles, legend.texts))

        lookup_artist = {}
        lookup_handle = {}
        for artist in legend.axes.get_children():
            if artist.get_label() in labels:
                handle = label2handle[artist.get_label()]
                lookup_handle[artist] = handle
                lookup_artist[handle] = artist
                lookup_artist[handle2text[handle]] = artist

        lookup_handle.update(zip(handles, handles))
        lookup_handle.update(zip(legend.texts, handles))

        return lookup_artist, lookup_handle

    def on_pick(self, event):
        handle = event.artist
        if handle in self.lookup_artist:

            artist = self.lookup_artist[handle]
            artist.set_visible(not artist.get_visible())
            self.update()

    def on_click(self, event):
        if event.button == 3:
            visible = False
        elif event.button == 2:
            visible = True
        else:
            return

        for artist in self.lookup_artist.values():
            artist.set_visible(visible)
        self.update()

    def update(self):
        for artist in self.lookup_artist.values():
            handle = self.lookup_handle[artist]
            if artist.get_visible():
                handle.set_visible(True)
            else:
                handle.set_visible(False)
        self.fig.canvas.draw()

    def show(self):
        plt.show()

if __name__ == '__main__':
    fig, ax, leg = main()
    plt.show()

This allows you to click on legend items to toggle their corresponding artists on/off. For example, you can go from this:

To this:

Answer 3

Inspired by @JoeKington's answer, here is what I use (a slightly modified version, that doesn't require ax, fig but can work directly with plt.plot(...); also plt.legend() is kept outside out the scope of the main object):

Ready-to-use example pltinteractivelegend.py:

import numpy as np
import matplotlib.pyplot as plt

class InteractiveLegend(object):
    def __init__(self, legend=None):
        if legend == None:
            legend = plt.gca().get_legend()
        self.legend = legend
        self.fig = legend.axes.figure
        self.lookup_artist, self.lookup_handle = self._build_lookups(legend)
        self._setup_connections()
        self.update()
    def _setup_connections(self):
        for artist in self.legend.texts + self.legend.legendHandles:
            artist.set_picker(10) # 10 points tolerance
        self.fig.canvas.mpl_connect('pick_event', self.on_pick)
        self.fig.canvas.mpl_connect('button_press_event', self.on_click)
    def _build_lookups(self, legend):
        labels = [t.get_text() for t in legend.texts]
        handles = legend.legendHandles
        label2handle = dict(zip(labels, handles))
        handle2text = dict(zip(handles, legend.texts))
        lookup_artist = {}
        lookup_handle = {}
        for artist in legend.axes.get_children():
            if artist.get_label() in labels:
                handle = label2handle[artist.get_label()]
                lookup_handle[artist] = handle
                lookup_artist[handle] = artist
                lookup_artist[handle2text[handle]] = artist
        lookup_handle.update(zip(handles, handles))
        lookup_handle.update(zip(legend.texts, handles))
        return lookup_artist, lookup_handle
    def on_pick(self, event):
        handle = event.artist
        if handle in self.lookup_artist:
            artist = self.lookup_artist[handle]
            artist.set_visible(not artist.get_visible())
            self.update()
    def on_click(self, event):
        if event.button == 3:
            visible = False
        elif event.button == 2:
            visible = True
        else:
            return
        for artist in self.lookup_artist.values():
            artist.set_visible(visible)
        self.update()
    def update(self):
        for artist in self.lookup_artist.values():
            handle = self.lookup_handle[artist]
            if artist.get_visible():
                handle.set_visible(True)
            else:
                handle.set_visible(False)
        self.fig.canvas.draw()

if __name__ == '__main__':
    for i in range(20):
        plt.plot(np.random.randn(1000), label=i)
    plt.legend()    
    leg = InteractiveLegend()
    plt.show()

Usage as a library:

import numpy as np
import matplotlib.pyplot as plt
import pltinteractivelegend

for i in range(20):
    plt.plot(np.random.randn(1000), label=i)
plt.legend()    
leg = pltinteractivelegend.InteractiveLegend()  # mandatory: keep the object with leg = ...; else it won't work
plt.show()