1"""
2===================
3Image Slices Viewer
4===================
5
6Scroll through 2D image slices of a 3D array.
7"""
8
9import numpy as np
10import matplotlib.pyplot as plt
11
12
13# Fixing random state for reproducibility
14np.random.seed(19680801)
15
16
17class IndexTracker:
18    def __init__(self, ax, X):
19        self.ax = ax
20        ax.set_title('use scroll wheel to navigate images')
21
22        self.X = X
23        rows, cols, self.slices = X.shape
24        self.ind = self.slices//2
25
26        self.im = ax.imshow(self.X[:, :, self.ind])
27        self.update()
28
29    def on_scroll(self, event):
30        print("%s %s" % (event.button, event.step))
31        if event.button == 'up':
32            self.ind = (self.ind + 1) % self.slices
33        else:
34            self.ind = (self.ind - 1) % self.slices
35        self.update()
36
37    def update(self):
38        self.im.set_data(self.X[:, :, self.ind])
39        self.ax.set_ylabel('slice %s' % self.ind)
40        self.im.axes.figure.canvas.draw()
41
42
43fig, ax = plt.subplots(1, 1)
44
45X = np.random.rand(20, 20, 40)
46
47tracker = IndexTracker(ax, X)
48
49
50fig.canvas.mpl_connect('scroll_event', tracker.on_scroll)
51plt.show()
52