Matplotlib.axes.Axes.set_contains() in Python

Matplotlib is a library in Python and it is numerical – mathematical extension for NumPy library. The Axes Class contains most of the figure elements: Axis, Tick, Line2D, Text, Polygon, etc., and sets the coordinate system. And the instances of Axes supports callbacks through a callbacks attribute.

matplotlib.axes.Axes.set_contains() Function

The Axes.set_contains() function in axes module of matplotlib library is used to define a custom contains test for the artist.

Syntax: Axes.set_contains(self, picker)

Parameters: This method accept the following parameters as discussed below:

• picker : This parameter is the custom picker function to evaluate if an event is within the artist.

Returns: This method does not return any value.

Below examples illustrate the matplotlib.axes.Axes.set_contains() function in matplotlib.axes:

Example 1:

# Implementation of matplotlib function
import matplotlib.pyplot as plt
from matplotlib.lines import Line2D
from matplotlib.patches import Rectangle
from matplotlib.text import Text
from matplotlib.image import AxesImage
import numpy as np
from numpy.random import rand


fig, (ax1, ax2) = plt.subplots(2, 1)
ax1.set_ylabel('ylabel', picker = True,
               bbox = dict(facecolor ='red'))

line, = ax1.plot(rand(100), 'go-')

ax2.bar(range(10), rand(10), picker = True)

for label in ax2.get_xticklabels():
    label.set_picker(True)

def onpick1(event):

    if isinstance(event.artist, Line2D):
        thisline = event.artist
        xdata = thisline.get_xdata()
        ydata = thisline.get_ydata()
        ind = event.ind
        print('onpick1 line:', np.column_stack([xdata[ind],
                                                ydata[ind]]))

    elif isinstance(event.artist, Rectangle):
        patch = event.artist
        print('onpick1 patch:', patch.get_path())

    elif isinstance(event.artist, Text):
        text = event.artist
        print('onpick1 text:', text.get_text())

ax2.set_contains(onpick1)
fig.suptitle('matplotlib.axes.Axes.set_contains() function\
Example', fontweight ="bold")

plt.show()

Output:

Example 2:

# Implementation of matplotlib function
import matplotlib.pyplot as plt
from matplotlib.lines import Line2D
from matplotlib.patches import Rectangle
from matplotlib.text import Text
from matplotlib.image import AxesImage
import numpy as np
from numpy.random import rand


def line_picker(line, mouseevent):

    if mouseevent.xdata is None:
        return False, dict()

    xdata = line.get_xdata()
    ydata = line.get_ydata()
    maxd = 0.05
    d = np.sqrt(
        (xdata - mouseevent.xdata)**2 + (ydata - mouseevent.ydata)**2)

    ind, = np.nonzero(d <= maxd)

    if len(ind):

        pickx = xdata[ind]
        picky = ydata[ind]
        props = dict(ind = ind, pickx = pickx, picky = picky)
        return True, props

    else:
        return False, dict()

def onpick2(event):

    print('Result :', event.pickx, event.picky)

fig, ax = plt.subplots()
ax.plot(rand(100), rand(100), 'o')

ax.set_contains(picker = line_picker)

fig.canvas.mpl_connect('pick_event', onpick2)

fig.suptitle('matplotlib.axes.Axes.set_contains()\
function Example', fontweight ="bold")

plt.show()

Output: