From dc0c7503f78ca550e002bda9584a825953f29607 Mon Sep 17 00:00:00 2001 From: Thomas A Caswell Date: Sat, 5 Nov 2022 22:57:49 -0400 Subject: [PATCH] Backport PR #24366: DOC: Improve Image Slices Viewer example --- .../event_handling/image_slices_viewer.py | 46 ++++++++----------- lib/matplotlib/backend_bases.py | 8 ++++ 2 files changed, 28 insertions(+), 26 deletions(-) diff --git a/examples/event_handling/image_slices_viewer.py b/examples/event_handling/image_slices_viewer.py index 6431d38ac541..8a2860902bce 100644 --- a/examples/event_handling/image_slices_viewer.py +++ b/examples/event_handling/image_slices_viewer.py @@ -1,9 +1,10 @@ """ -=================== -Image Slices Viewer -=================== +============ +Scroll event +============ -Scroll through 2D image slices of a 3D array. +In this example a scroll wheel event is used to scroll through 2D slices of +3D data. .. note:: This example exercises the interactive capabilities of Matplotlib, and this @@ -18,42 +19,35 @@ import matplotlib.pyplot as plt -# Fixing random state for reproducibility -np.random.seed(19680801) - - class IndexTracker: def __init__(self, ax, X): - self.ax = ax - ax.set_title('use scroll wheel to navigate images') - + self.index = 0 self.X = X - rows, cols, self.slices = X.shape - self.ind = self.slices//2 - - self.im = ax.imshow(self.X[:, :, self.ind]) + self.ax = ax + self.im = ax.imshow(self.X[:, :, self.index]) self.update() def on_scroll(self, event): - print("%s %s" % (event.button, event.step)) - if event.button == 'up': - self.ind = (self.ind + 1) % self.slices - else: - self.ind = (self.ind - 1) % self.slices + print(event.button, event.step) + increment = 1 if event.button == 'up' else -1 + max_index = self.X.shape[-1] - 1 + self.index = np.clip(self.index + increment, 0, max_index) self.update() def update(self): - self.im.set_data(self.X[:, :, self.ind]) - self.ax.set_ylabel('slice %s' % self.ind) + self.im.set_data(self.X[:, :, self.index]) + self.ax.set_title( + f'Use scroll wheel to navigate\nindex {self.index}') self.im.axes.figure.canvas.draw() -fig, ax = plt.subplots(1, 1) - -X = np.random.rand(20, 20, 40) +x, y, z = np.ogrid[-10:10:100j, -10:10:100j, 1:10:20j] +X = np.sin(x * y * z) / (x * y * z) +fig, ax = plt.subplots() +# create an IndexTracker and make sure it lives during the whole +# lifetime of the figure by assigning it to a variable tracker = IndexTracker(ax, X) - fig.canvas.mpl_connect('scroll_event', tracker.on_scroll) plt.show() diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py index 6e603cafbef0..c93c6913f44e 100644 --- a/lib/matplotlib/backend_bases.py +++ b/lib/matplotlib/backend_bases.py @@ -2421,6 +2421,14 @@ def func(event: Event) -> Any be set to the mouse location in data coordinates. See `.KeyEvent` and `.MouseEvent` for more info. + .. note:: + + If func is a method, this only stores a weak reference to the + method. Thus, the figure does not influence the lifetime of + the associated object. Usually, you want to make sure that the + object is kept alive throughout the lifetime of the figure by + holding a reference to it. + Returns ------- cid pFad - Phonifier reborn

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