python - savefig PGF - 运行时错误 : Cannot get window extent w/o renderer

Question

我正在尝试在 pyplot 中保存一个边距很小的图形。

以下代码与 PDF 输出完美配合:

from matplotlib import pyplot as plt
plt.plot(1)
plt.savefig('test.pdf', bbox_inches='tight')

但不支持 PGF 输出

plt.savefig('test.pgf', bbox_inches='tight')

因为它返回运行时错误:无法获取没有渲染器的窗口范围。

为什么会发生这种情况？有办法解决吗？

Ubuntu 13.04 上的 matplotlib 1.3.0rc2

python -c "from matplotlib import pyplot as plt; plt.plot(1); plt.savefig('test.pgf', bbox_inches='tight');"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "PYTHONPATH/matplotlib-1.3.0rc2-py2.7-linux-x86_64.egg/matplotlib/pyplot.py", line 561, in savefig
    return fig.savefig(*args, **kwargs)
  File "PYTHONPATH/matplotlib-1.3.0rc2-py2.7-linux-x86_64.egg/matplotlib/figure.py", line 1410, in savefig
    self.canvas.print_figure(*args, **kwargs)
  File "PYTHONPATH/matplotlib-1.3.0rc2-py2.7-linux-x86_64.egg/matplotlib/backends/backend_qt4agg.py", line 161, in print_figure
    FigureCanvasAgg.print_figure(self, *args, **kwargs)
  File "PYTHONPATH/matplotlib-1.3.0rc2-py2.7-linux-x86_64.egg/matplotlib/backend_bases.py", line 2169, in print_figure
    bbox_inches = self.figure.get_tightbbox(renderer)
  File "PYTHONPATH/matplotlib-1.3.0rc2-py2.7-linux-x86_64.egg/matplotlib/figure.py", line 1551, in get_tightbbox
    bb.append(ax.get_tightbbox(renderer))
  File "PYTHONPATH/matplotlib-1.3.0rc2-py2.7-linux-x86_64.egg/matplotlib/axes.py", line 9153, in get_tightbbox
    bb_xaxis = self.xaxis.get_tightbbox(renderer)
  File "PYTHONPATH/matplotlib-1.3.0rc2-py2.7-linux-x86_64.egg/matplotlib/axis.py", line 1055, in get_tightbbox
    renderer)
  File "PYTHONPATH/matplotlib-1.3.0rc2-py2.7-linux-x86_64.egg/matplotlib/axis.py", line 1038, in _get_tick_bboxes
    extent = tick.label1.get_window_extent(renderer)
  File "PYTHONPATH/matplotlib-1.3.0rc2-py2.7-linux-x86_64.egg/matplotlib/text.py", line 751, in get_window_extent
    raise RuntimeError('Cannot get window extent w/o renderer')
RuntimeError: Cannot get window extent w/o renderer

Answer 1

顺便说一句，有一个解决方法。通常 PGF/TikZ 图像的范围会自动调整，以使其与绘图相匹配。为了保留 matplotlib 预期的图形大小，这些行被添加到输出中:

\pgfpathrectangle{\pgfpointorigin}{\pgfqpoint{8.000000in}{6.000000in}}%
\pgfusepath{use as bounding box}%

如果从 PGF 输出中删除最顶部的这些行，您应该删除图形周围的任何额外空间。

在 1.3 版本中使用 plt.tight_layout() 或更好的 plt.figure(tight_layout=True) 是另一种方法(与 PGF 完美配合)和 PGF->PDF)，尽管有点不同。它重新计算图形的布局，使其适合给定的图形尺寸。我通常更喜欢这种方法，因为它还消除了文本元素重叠等问题。