"""

=============

Span Selector

=============

The SpanSelector is a mouse widget to select a xmin/xmax range and plot the

detail view of the selected region in the lower axes

"""

import numpy as np

import matplotlib.pyplot as plt

from matplotlib.widgets import SpanSelector

# Fixing random state for reproducibility

np.random.seed(19680801)

fig, (ax1, ax2) = plt.subplots(2, figsize=(8, 6))

ax1.set(facecolor='#FFFFCC')

x = np.arange(0.0, 5.0, 0.01)

y = np.sin(2*np.pi*x) + 0.5*np.random.randn(len(x))

ax1.plot(x, y, '-')

ax1.set_ylim(-2, 2)

ax1.set_title('Press left mouse button and drag to test')

ax2.set(facecolor='#FFFFCC')

line2, = ax2.plot(x, y, '-')

def onselect(xmin, xmax):

indmin, indmax = np.searchsorted(x, (xmin, xmax))

indmax = min(len(x) - 1, indmax)

thisx = x[indmin:indmax]

thisy = y[indmin:indmax]

line2.set_data(thisx, thisy)

ax2.set_xlim(thisx[0], thisx[-1])

ax2.set_ylim(thisy.min(), thisy.max())

fig.canvas.draw()

#############################################################################

# .. note::

#

# If the SpanSelector object is garbage collected you will lose the

# interactivity. You must keep a hard reference to it to prevent this.

#

span = SpanSelector(ax1, onselect, 'horizontal', useblit=True,

rectprops=dict(alpha=0.5, facecolor='red'))

# Set useblit=True on most backends for enhanced performance.

plt.show()