导入 matplotlib.pyplot 挂起

Question

我正在尝试在 OS X 10.8.4 上启动并运行 matplotlib。我已经安装了 matplotlib 和依赖项（libping、freetype、numpy、scipy）。我可以很好地导入 matplotlib。但是，如果我尝试导入 matplotlib.pyplot，它就会挂起。没有错误，只是什么也没发生。

>>> import matplotlib.pyplot

...我已经等了大概 20 分钟，没有任何反应。我使用的是 1.2.1 版，但我什至卸载了它并尝试了 1.2.0 版，但无济于事。我在 SO 上看到了一些关于 matplotlib.pyplot 导入错误的问题，但没有任何问题。然后我尝试使用 Enthought/Canopy python 发行版让它工作，但同样的悬而未决的问题。如果我终止导入，我会看到以下内容：

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/pyplot.py", line 26, in <module>
    from matplotlib.figure import Figure, figaspect
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/figure.py", line 34, in <module>
    import matplotlib.colorbar as cbar
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/colorbar.py", line 29, in <module>
    import matplotlib.collections as collections
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/collections.py", line 23, in <module>
    import matplotlib.backend_bases as backend_bases
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/backend_bases.py", line 37, in <module>
    import matplotlib.widgets as widgets
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/widgets.py", line 17, in <module>
    from lines import Line2D
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/lines.py", line 25, in <module>
    from matplotlib.font_manager import FontProperties
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/font_manager.py", line 1335, in <module>
    _rebuild()
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/font_manager.py", line 1322, in _rebuild
    fontManager = FontManager()
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/font_manager.py", line 980, in __init__
    self.ttffiles = findSystemFonts(paths) + findSystemFonts()
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/font_manager.py", line 317, in findSystemFonts
    for f in get_fontconfig_fonts(fontext):
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/site-packages/matplotlib/font_manager.py", line 274, in get_fontconfig_fonts
    output = pipe.communicate()[0]
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/subprocess.py", line 746, in communicate
    stdout = _eintr_retry_call(self.stdout.read)
  File "/Applications/Canopy.app/appdata/canopy-1.0.3.1262.macosx-x86_64/Canopy.app/Contents/lib/python2.7/subprocess.py", line 478, in _eintr_retry_call
    return func(*args)
KeyboardInterrupt

当我使用 OS X 自带的默认 python 2.7 时，输出是一样的。

更新

让import matplotlib.pyplot 运行几个小时然后中断导入现在给我这个输出：

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Library/Python/2.7/site-packages/matplotlib/pyplot.py", line 26, in <module>
    from matplotlib.figure import Figure, figaspect
  File "/Library/Python/2.7/site-packages/matplotlib/figure.py", line 34, in <module>
    import matplotlib.colorbar as cbar
  File "/Library/Python/2.7/site-packages/matplotlib/colorbar.py", line 29, in <module>
    import matplotlib.collections as collections
  File "/Library/Python/2.7/site-packages/matplotlib/collections.py", line 23, in <module>
    import matplotlib.backend_bases as backend_bases
  File "/Library/Python/2.7/site-packages/matplotlib/backend_bases.py", line 37, in <module>
    import matplotlib.widgets as widgets
  File "/Library/Python/2.7/site-packages/matplotlib/widgets.py", line 17, in <module>
    from lines import Line2D
  File "/Library/Python/2.7/site-packages/matplotlib/lines.py", line 25, in <module>
    from matplotlib.font_manager import FontProperties
  File "/Library/Python/2.7/site-packages/matplotlib/font_manager.py", line 1335, in <module>
    _rebuild()
  File "/Library/Python/2.7/site-packages/matplotlib/font_manager.py", line 1322, in _rebuild
    fontManager = FontManager()
  File "/Library/Python/2.7/site-packages/matplotlib/font_manager.py", line 980, in __init__
    self.ttffiles = findSystemFonts(paths) + findSystemFonts()
  File "/Library/Python/2.7/site-packages/matplotlib/font_manager.py", line 324, in findSystemFonts
    files = list_fonts(path, fontexts)
  File "/Library/Python/2.7/site-packages/matplotlib/font_manager.py", line 171, in list_fonts
    return cbook.listFiles(directory, pattern)
  File "/Library/Python/2.7/site-packages/matplotlib/cbook.py", line 944, in listFiles
    for dirname, dirs, files in os.walk(root):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 284, in walk
    if isdir(join(top, name)):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/genericpath.py", line 41, in isdir
    st = os.stat(s)
KeyboardInterrupt

有谁知道递归for x in walk(new_path, topdown, onerror, followlinks): 可能表示什么？

Answer 1

您可以通过执行以下操作来解决 Mac OS X Mavericks 和 Yosemite 上的问题：

cd ~/.matplotlib/
fc-list  # Should take a couple minutes.

fc-list 完成运行后，您将能够使用import matplotlib.pyplot as plt 导入包。这是带有解决方案的github issue。这个bug似乎和字体缓存有关。

Answer 2

我知道发生了什么。希望该解决方案对其他人有用。在/usr/X11/lib 文件夹中，有一个指向自身的目录的符号链接。这似乎创建了一个无限循环。当我删除链接时，导入工作正常。

Answer 3

我在 Linux 上遇到了同样的问题。

原来 matplotlib 在确定要使用的 GUI 后端时遇到了一些问题。

明确表示它使用 Tkinter 背景 - 默认情况下它使用以下命令解决了问题：

%matplotlib tk

接下来是导入

import matplotlib.pyplot as plt

按预期工作。