Python 如何将图像作为背景添加到 matplotlib 图(不是绘图，而是空白ala set_face() )

发布于09月30日

我试图将一幅图像添加到matplotlib图形的各个子情节后面的"空白"中.

大多数类似这一主题的讨论都是为情节本身添加图像，但我还没有遇到改变整体画布背景的方法.

我找到的最相似的函数是set_facecolor()，但这只允许将单一 colored颜色设置为背景.

fig, ax = plt.subplots(2,2)
fig.patch.set_facecolor('xkcd:mint green')
plt.show()

然而，我正在寻找一种解决方案，以导入情节背后的图像，类似于此(手动制作):

我已经在谷歌上搜索过了，搜索过了，并查看了matplotlib文档，但我只能得到plt.imshow(image)或set_facecolor()或类似的结果.

推荐答案

您可以使用与图大小相同的虚拟子图，并将背景绘制到该子图上.

import matplotlib as mpl
import matplotlib.pyplot as plt
import numpy as np

image = plt.imread('test.jpg') 

# make ticks white, for readability on colored background
mpl.rcParams.update({'xtick.color': "white",
                     'ytick.color': "white",
                     'axes.labelcolor': "white"}) 
# create a figure with 4 subplots, with the same aspect ratio as the image
width = 8
fig, axs = plt.subplots(nrows=2, ncols=2, figsize=(width, width * image.shape[0] / image.shape[1]))
for ax in np.ravel(axs):
    ax.patch.set_alpha(0.7) # make subplots semi-transparent

background_ax = plt.axes([0, 0, 1, 1]) # create a dummy subplot for the background
background_ax.set_zorder(-1) # set the background subplot behind the others
background_ax.imshow(image, aspect='auto') # show the backgroud image

# plot something onto the subplots
t = np.linspace(0, 8 * np.pi, 2000)
for i in range(2):
    for j in range(2):
        axs[i, j].plot(np.sin(t * (i + 2)), np.sin(t * (j + 4)))

# plt.tight_layout() gives a warning, as the background ax won't be taken into account,
# but normally the other subplots will be rearranged to nicely fill the figure
plt.tight_layout() 
plt.show()