matplotlib:添加一个图片作为注解并旋转它

Question

我尝试在matplotlib图的某个位置添加一些图像。

图像应独立于底层图形的缩放因子，但应具有一定的旋转。(实际上，我想显示一个飞机符号和一个带有正确航向的跑道符号，作为计算出的路径的叠加，这是一个普通的matplotlib线状图。)

我按照这里的建议将图像插入到了正确的位置和正确的大小：How to insert an image (a picture or a photo) in a matplotlib figure，但我还不能将显示的图像旋转到正确的标题中。

有什么想法吗？老实说，我对Matplotlib注解是个新手，所以我不知道用谷歌搜索什么。

干杯,

费利克斯

Answer 1

我不确定这是否回答了你的问题，但希望它能给你一个起点！我还没有完成角度的计算，但再次，希望它能给你一些想法。

import matplotlib.pyplot as plt
from matplotlib.offsetbox import OffsetImage, AnnotationBbox
import numpy as np
from scipy import interpolate, ndimage

# Set x value of image centre
x_image = 7


# Set up matplotlib figure with axis
fig, ax = plt.subplots()


# Create arbitrary curve for path
def f_curve(x):
    return 0.1*x**2

x = np.arange(0,10,0.01)   # start,stop,step
y = f_curve(x)

plt.plot(x, y)


# create spline function (to get image centre y-value and derivative at that point)
f = interpolate.InterpolatedUnivariateSpline(x, y, k=1)
xs = np.linspace(min(x), max(x), 100)
plt.plot(xs, f(xs), 'g', lw=3)


# Get y-value for image centre 
# (replace this with your own y-value if you already know it)
y_image = f(x_image)


# Read in image
img = plt.imread('batman.png')

# Convert image into numpy array
image_arr = np.array(img)

# Calculate the derivative of the path curve at x_image to get the angle of rotation required
angle = np.rad2deg(f.derivative()(x_image))-90

# Rotate image
image_arr = ndimage.rotate(image_arr, angle, reshape=True)

# inspired by 
# https://moonbooks.org/Articles/How-to-insert-an-image-a-picture-or-a-photo-in-a-matplotlib-figure/
imagebox = OffsetImage(image_arr, zoom=0.2)
ab = AnnotationBbox(imagebox, (x_image, y_image),bboxprops={'edgecolor':'none','alpha':0.1})
ax.add_artist(ab)
plt.draw()

plt.show()

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