如何更新 Matplotlib 上的形状？

Question

我在图像上绘制了一个矩形。我想移动那个形状，即改变它的坐标，绘制新形状并删除旧形状（背景图像保持不变）

类似于此代码。它显示了一个矩形三次，但我希望在绘制绿色形状时删除红色形状，蓝色形状也类似。当蓝色出现时去除绿色。

import matplotlib.pyplot as plt
import numpy as np

# Get an example image
image_file = r"image_splash.jpg"
img = plt.imread(image_file)

# Make some example data
x = np.array([475, 475, 675, 675, 475])
y = np.array([100, 200, 200, 100, 100])

# Create a figure
_dpi = 72
fig = plt.figure(1, figsize=(1000/_dpi, 1000/_dpi), dpi=_dpi)
ax = fig.add_subplot(1, 1, 1)
ax.set_aspect('equal')

# Show the image
ax.imshow(img)

# Now, loop through the offset array and update the shape 
# (This obviously doesnt work, it plots all three shapes)
rgb = ['r', 'g', 'b']
offset = [0, 150, 300]
plt.plot(x, y + offset[0], c=rgb[0]) # draw the red rect
plt.plot(x, y + offset[1], c=rgb[1]) # should remove the red and draw the green
plt.plot(x, y + offset[2], c=rgb[2]) # should remove the green and draw the blue

Answer 1

你可以试试matplotlib的动画api如下图

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation

fig, ax = plt.subplots()
xdata, ydata = [], []
(ln,) = plt.plot([], [], "r")

x = np.array([475, 475, 675, 675, 475])
y = np.array([100, 200, 200, 100, 100])
offset = [0, 150, 300]
colors = {
    0: "red",
    150: "green",
    300: "blue",
}


def init():
    ax.set_xlim(0, 1000)
    ax.set_ylim(0, 1000)
    return (ln,)


def update(_offset):
    ln.set_data(x, y + _offset)
    ln.set_color(colors[_offset])
    return (ln,)


def gety():
    for i in range(1000):
        yield offset[i % 3]


ani = FuncAnimation(fig, update, frames=gety(), init_func=init, blit=True)
plt.show()

如何更新 Matplotlib 上的形状？

How to update a shape on Matplotlib?

python

matplotlib

matplotlib-animation