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Joe
Asked: 2024-05-21 23:45:51 +0800 CST

如何将 matplotlib imshow 嵌入另一个中

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这是一个代表

import urllib # to retrieve the file from the internet
from PIL import Image # to interpret the bytes as an image
import numpy as np # to work with arrays of numbers (the image is an array of pixels)
import matplotlib.pyplot as plt # for general plotting

# The URL for the file
url = r"https://upload.wikimedia.org/wikipedia/en/9/9d/The_Tilled_Field.jpg"

img = np.array(Image.open(urllib.request.urlopen(url)))

# Make a figure and axes
fig, ax = plt.subplots(figsize=(4.5, 6.4))

# Add the image to the axes
ax.imshow(img);

# Say where to put the ticks on the axes
ax.set_xticks(range(0,1300,100), minor=False)
ax.set_xticks(range(0,1300,20), minor=True)
ax.set_yticks(range(0,900,100), minor=False)
ax.set_yticks(range(0,900,20), minor=True)

# Add some gridlines
ax.grid(which='minor', color='grey');


# I want this figure to be inlayed inside the bigger figure
ax.imshow(img, extent=[400,528,200,290]);

我认为范围会使第二个ax.imshow图像放入第一个图像内，但事实并非如此。

如果我删除该行，它就会完全符合我的预期。但是当我使用这条线时，而不是在指定范围内绘制在上一张图像之上，它似乎创建了一个全新的绘图。

有谁知道我做错了什么？

matplotlib

1 个回答

  1. Best Answer

    我认为这里的解决方案是为镶嵌创建一个新的轴。图像通常不共享公共坐标系，并且如果图像不透明，则在同一轴上绘制时它们不会显示在彼此的顶部。棘手的部分是将坐标从参考图像转换为图形坐标，特别是因为 matplotlib 中的图像的原点位于顶部，导致 y 轴倒转。

    然而，这是一个最小的例子：

    import urllib
from PIL import Image
import numpy as np
import matplotlib.pyplot as plt

url = r"https://upload.wikimedia.org/wikipedia/en/9/9d/The_Tilled_Field.jpg"
img = np.array(Image.open(urllib.request.urlopen(url)))

img_height, img_width = img.shape[:2]

fig_width = 6.4
fig, ax = plt.subplots(figsize=(fig_width, fig_width / img_width * img_height))

ax.imshow(img.sum(axis=2), cmap='gray');
ax.axis('off');

data_to_fig = ax.transData + ax.figure.transFigure.inverted()

# this is given in coordinates of the first image, with origin at the bottom left in units of pixels
left, bottom, width = 0, 0, 300 
height = width / img_width * img_height

(left, bottom), (right, upper)  = data_to_fig.transform([(left, img_height - bottom), (left + width, img_height - bottom - height)])

ax_inlay = fig.add_axes((left, bottom, right - left, upper - bottom))
ax_inlay.axis('off')

ax_inlay.imshow(img);

    这会创建：

    在此输入图像描述

    我希望这有帮助！

    • 1

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