导出具有透明背景的matplotlib

Question

我正在尝试导出一个带有透明背景的matplotlib绘图，因为它是一个圆，我需要粘贴到另一个画布上（没有角）。

我遵循了这里的示例：如何使用透明背景从matplotlib导出绘图？

示例代码：

import matplotlib.pyplot as plt
from PIL import Image, ImageFont, ImageDraw

path = '...'

SomeCanvas1 = Image.new('RGB', (750, 750), '#36454F')

fig, ax = plt.subplots(figsize=(6, 6))
wedgeprops = {'width':0.3, 'edgecolor':'white', 'linewidth':2}
ax.pie([1-0.33,0.33], wedgeprops=wedgeprops, startangle=90, colors=['#BABABA', '#0087AE'])
plt.text(0, 0, '33%', ha='center', va='center', fontsize=42)
fig.savefig(path+'donut1.png', transparent=True)

imgDonut = Image.open(path+'donut1.png')
w,h = imgDonut.size

SomeCanvas1.paste(imgDonut, (int(0.5*(750-w)),int(0.5*(750-h))))
SomeCanvas1.save(path+'test1.png')

这里给出的示例是：如何使用Matplotlib设置图形背景颜色的不透明度

示例代码：

SomeCanvas2 = Image.new('RGB', (750, 750), '#36454F')

fig, ax = plt.subplots(figsize=(6, 6))
fig.patch.set_facecolor('None')
fig.patch.set_alpha(0)
wedgeprops = {'width':0.3, 'edgecolor':'white', 'linewidth':2}
ax.pie([1-0.33,0.33], wedgeprops=wedgeprops, startangle=90, colors=['#BABABA', '#0087AE'])
plt.text(0, 0, '33%', ha='center', va='center', fontsize=42)
fig.savefig(path+'donut2.png', facecolor=fig.get_facecolor(), edgecolor='none')

imgDonut = Image.open(path+'donut2.png')
w,h = imgDonut.size

SomeCanvas2.paste(imgDonut, (int(0.5*(750-w)),int(0.5*(750-h))))
SomeCanvas2.save(path+'test2.png')

以及这里的例子：导出图在. png与透明背景

但这对我不起作用。当我粘贴到画布上时，我最终得到：

我需要它紧紧地围绕着油炸圈饼，没有方形的角落。

我的代码出了什么问题？

编辑：我在Windows 10和使用原子IDE。我不确定这是否会有所不同...

Answer 1

这对我很有用：

import matplotlib.pyplot as plt
from PIL import Image, ImageFont, ImageDraw

path = '...'

SomeCanvas1 = Image.new('RGB', (750, 750), '#36454F')

fig, ax = plt.subplots(figsize=(6, 6))
wedgeprops = {'width':0.3, 'edgecolor':'white', 'linewidth':2}
ax.pie([1-0.33,0.33], wedgeprops=wedgeprops, startangle=90, colors=['#BABABA', '#0087AE'])
plt.text(0, 0, '33%', ha='center', va='center', fontsize=42)
fig.savefig(path+'donut1.png', transparent=True)

imgDonut = Image.open(path+'donut1.png')
w,h = imgDonut.size

SomeCanvas1.paste(imgDonut, (int(0.5*(750-w)),int(0.5*(750-h))))
SomeCanvas1.save(path+'test1.png')
fig.patch.set_alpha(0)

输出是（我有黑色背景-

----edit---

设法让它透明！

import matplotlib.pyplot as plt
from PIL import Image, ImageFont, ImageDraw

path = '...'

SomeCanvas1 = Image.new('RGB', (750, 750), '#36454F')

fig, ax = plt.subplots(figsize=(6, 6))
wedgeprops = {'width':0.3, 'edgecolor':'white', 'linewidth':2}
ax.pie([1-0.33,0.33], wedgeprops=wedgeprops, startangle=90, colors=['#BABABA', '#0087AE'])
plt.text(0, 0, '33%', ha='center', va='center', fontsize=42)
fig.savefig(path+'donut1.png', transparent=True)
fig.patch.set_alpha(0)

SomeCanvas1.save(path+'test1.png')

foreground = path+'donut1.png'
imgfore = Image.open(foreground, 'r')
background = path+'test1.png'
imgback = Image.open(background, 'r')

merged = Image.new('RGBA', (w,h), (0, 0, 0, 0))
merged.paste(imgback, (0,0))
merged.paste(imgfore, (0,0), mask=imgfore)
merged.save((path+"merged.png"), format="png")

在这种情况下，您将产生3个图像文件。这是合并文件：