Python 使用 matplotlib 和 numpy 在图像上绘制圆圈
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drawing circles on image with matplotlib and numpy
提问by orkan
I have numpy arrays which hold circle centers.
我有保存圆心的 numpy 数组。
import matplotlib.pylab as plt
import numpy as np
npX = np.asarray(X)
npY = np.asarray(Y)
plt.imshow(img)
// TO-DO
plt.show()
How can I show circles at the given positions on my image?
如何在图像上的给定位置显示圆圈？
采纳答案by tmdavison
You can do this with the matplotlib.patches.Circlepatch.
你可以用matplotlib.patches.Circle补丁来做到这一点。
For your example, we need to loop through the X and Y arrays, and then create a circle patch for each coordinate.
对于您的示例，我们需要遍历 X 和 Y 数组，然后为每个坐标创建一个圆形补丁。
Here's an example placing circles on top of an image (from the matplotlib.cbook)
这是在图像顶部放置圆圈的示例（来自matplotlib.cbook）
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.patches import Circle
# Get an example image
import matplotlib.cbook as cbook
image_file = cbook.get_sample_data('grace_hopper.png')
img = plt.imread(image_file)
# Make some example data
x = np.random.rand(5)*img.shape[1]
y = np.random.rand(5)*img.shape[0]
# Create a figure. Equal aspect so circles look circular
fig,ax = plt.subplots(1)
ax.set_aspect('equal')
# Show the image
ax.imshow(img)
# Now, loop through coord arrays, and create a circle at each x,y pair
for xx,yy in zip(x,y):
circ = Circle((xx,yy),50)
ax.add_patch(circ)
# Show the image
plt.show()
