保存为.pdf时,Matplotlib图失去透明度

Question

我看到与此问题完全相同的问题:Matplotlib Plots在保存为.ps/.eps时失去透明度,除了我试图输出到PDF而不是ps/eps.

上一个问题的答案指出,eps不支持透明度,并建议光栅化或保存为PDF.当我保存为png时,我确实得到正确的输出,所以看起来好像matplotlib正确处理透明度,但后端失败了.显然,PDF 确实支持透明度,因此我尝试使用的格式不是问题.

我使用默认的MacOSX matplotlib后端并使用matplotlib 1.4.1在OS X(Yosemite)中运行.是否有任何理由说明此设置无法生成透明的PDF输出？

这曾经在过去工作(使用OS X Mavericks和早期版本的matplotlib),但我不确定究竟是什么变化导致了这个问题.

如果运行以下代码,则问题可以在with_hatch.pdf中看到,但不能在任何其他输出文件中看到.

#! /usr/bin/env python
import matplotlib.pyplot as plt

fig = plt.figure( figsize=(6, 6), dpi=100, facecolor='white' )
ax = fig.add_axes( [0.15, 0.1, 0.8, 0.85] )

bin_edges = [0.0, 0.5, 0.5, 1.0, 1.0, 1.5, 1.5, 2.0, 2.0, 2.5, 2.5, 3.0, 3.0, 3.5, 3.5, 4.0, 4.0, 4.5, 4.5, 5.0, 5.0, 5.5, 5.5, 6.0, 6.0, 7.0, 7.0, 8.0]
y_low     = [0.9581631739289882, 0.9581631739289882, 0.8966054746563691, 0.8966054746563691, 0.8369962202270926, 0.8369962202270926, 0.7824880045351325, 0.7824880045351325, 0.7231695683685057, 0.7231695683685057, 0.6673767757896321, 0.6673767757896321, 0.6083447707111752, 0.6083447707111752, 0.5602384968623321, 0.5602384968623321, 0.5109567893600544, 0.5109567893600544, 0.4707872827805316, 0.4707872827805316, 0.4304527769718274, 0.4304527769718274, 0.39024135798617826, 0.39024135798617826, 0.3593458738615755, 0.3593458738615755, 0.3275704585658484, 0.3275704585658484]
y_high    = [0.9762065896798683, 0.9762065896798683, 0.9227253843496172, 0.9227253843496172, 0.8738222849514, 0.8738222849514, 0.8299500683866315, 0.8299500683866315, 0.7810616940586165, 0.7810616940586165, 0.7357506442258693, 0.7357506442258693, 0.6852756294051707, 0.6852756294051707, 0.6441575476130643, 0.6441575476130643, 0.5987788803224889, 0.5987788803224889, 0.5630257208701298, 0.5630257208701298, 0.5274860424153797, 0.5274860424153797, 0.4915335923551736, 0.4915335923551736, 0.46502435263727837, 0.46502435263727837, 0.43196895235913746, 0.43196895235913746]

ax.fill_between( bin_edges, y_low, y_high, facecolor='green', edgecolor='white', alpha=0.4 )

plt.savefig( 'without_hatch.pdf' )
plt.savefig( 'without_hatch.png' )

ax.fill_between( bin_edges, y_low, y_high, facecolor='green', edgecolor='white', hatch='xxxx', alpha=0.4 )

plt.savefig( 'with_hatch.pdf' )
plt.savefig( 'with_hatch.png' )

现在提交给matplotlib bug跟踪器:https://github.com/matplotlib/matplotlib/issues/3841

Answer 1

在过去 7 年的某个时候，这个问题在matplotlib. 请参阅 matplotlib GitHub 上的讨论： https ://github.com/matplotlib/matplotlib/issues/3841 。