Question

HeJ小鼠，

我正在使用与macports一起发布的matplotlib的最新版本（1.2.0）。我遇到了运行此代码的AssertionError（我猜这源于内部测试）

#!/usr/bin/env python

import numpy as np
import matplotlib.pyplot as plt

X,Y = np.meshgrid(np.arange(0, 2*np.pi, .2), np.arange(0, 2*np.pi, .2))
U = np.cos(X)
V = np.sin(Y)

Q = plt.quiver(U, V)
plt.quiverkey(Q, 0.5, .9, 1., 'Label')

plt.gca().add_patch(plt.Circle((10, 10), 1))
plt.savefig('test.pdf')

我需要以下三部分代码来重现错误：

箭袋图必须有一个用箭头键创建的密钥
必须为当前轴添加额外的补丁
我必须将图形保存为PDF（我可以很好地显示）

该错误不依赖于后端。我得到的回溯读取

Traceback (most recent call last):
  File "./test_quiver.py", line 15, in <module>
    plt.savefig('test.pdf')
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/pyplot.py", line 472, in savefig
    return fig.savefig(*args, **kwargs)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/figure.py", line 1363, in savefig
    self.canvas.print_figure(*args, **kwargs)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backend_bases.py", line 2093, in print_figure
    **kwargs)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backend_bases.py", line 1845, in print_pdf
    return pdf.print_pdf(*args, **kwargs)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/backend_pdf.py", line 2301, in print_pdf
    self.figure.draw(renderer)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/artist.py", line 54, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/figure.py", line 999, in draw
    func(*args)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/artist.py", line 54, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/axes.py", line 2086, in draw
    a.draw(renderer)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/artist.py", line 54, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/quiver.py", line 306, in draw
    self.vector.draw(renderer)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/artist.py", line 54, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/collections.py", line 755, in draw
    return Collection.draw(self, renderer)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/artist.py", line 54, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/collections.py", line 259, in draw
    self._offset_position)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/backend_pdf.py", line 1548, in draw_path_collection
    output(*self.gc.pop())
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/backend_pdf.py", line 2093, in pop
    assert self.parent is not None
AssertionError

如果它很重要：我使用的是Mac OS X 10.7.5，使用python 2.7.3和matplotlib 1.2.0。你也得到这个错误吗？这是matplotlib中的错误吗？它是系统依赖的吗？有一些解决方法吗？

Answer 1

您可以另存为eps或svg并转换为pdf。我发现制作小型pdf文件的最佳方法是在matplotlib中保存为eps，然后使用epstopdf。

svg也可以，你可以使用Inkscape转换为pdf。 svg的副作用是文本被转换为路径（没有嵌入字体），这在某些情况下可能是合乎需要的。

Answer 2

与Ubuntu 13.04（raring）一起发布的matplotlib（v 1.2.1）也有这个bug。我不知道在新版本中它是否仍然存在问题。

另一种解决方法（似乎对我有用）是完全删除draw_path_collection中的.../matplotlib/backends/backend_pdf.py功能。

在matplotlib 1.20中显示quvier键和补丁的bug的解决方法

2 个答案: