René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"format error saving eps figure using custom linestyle","articleBody":"\u003c!--To help us understand and resolve your issue, please fill out the form to the best of your ability.--\u003e\r\n\u003c!--You can feel free to delete the sections that do not apply.--\u003e\r\n\r\n### Bug report\r\n\r\n**Bug summary**\r\n\r\nWhen the `linestyle` is changed from a predefined value to on-off tuple, the resulting figure cannot be saved as eps file format.\r\n\r\n**Code for reproduction**\r\n\r\n\u003c!--A minimum code snippet required to reproduce the bug.\r\nPlease make sure to minimize the number of dependencies required, and provide\r\nany necessary plotted data.\r\nAvoid using threads, as Matplotlib is (explicitly) not thread-safe.--\u003e\r\n\r\n```python\r\n    import numpy as np\r\n    import matplotlib.pyplot as plt\r\n    x = y = np.linspace(-5, 5)\r\n    x, y = np.meshgrid(x, y)\r\n    z = x**2 + y**2 - 10\r\n    \r\n    plt.rcParams['contour.negative_linestyle'] = [7.0, 7.0]\r\n    f = plt.figure()\r\n    plt.contour(x, y, z, colors='k', levels=20)\r\n    f.savefig('test.eps')\r\n```\r\n\r\n**Actual outcome**\r\n\r\n\u003c!--The output produced by the above code, which may be a screenshot, console output, etc.--\u003e\r\n\r\n```\r\nTraceback (most recent call last):\r\n\r\n  File \"\u003cipython-input-12-d73b5c362b1b\u003e\", line 1, in \u003cmodule\u003e\r\n    f.savefig('test.eps')\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\figure.py\", line 2180, in savefig\r\n    self.canvas.print_figure(fname, **kwargs)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\backends\\backend_qt5agg.py\", line 88, in print_figure\r\n    super().print_figure(*args, **kwargs)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\backend_bases.py\", line 2082, in print_figure\r\n    **kwargs)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\backends\\backend_ps.py\", line 842, in print_eps\r\n    return self._print_ps(outfile, 'eps', *args, **kwargs)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\backends\\backend_ps.py\", line 871, in _print_ps\r\n    **kwargs)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\backends\\backend_ps.py\", line 966, in _print_figure\r\n    self.figure.draw(renderer)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\figure.py\", line 1709, in draw\r\n    renderer, self, artists, self.suppressComposite)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\image.py\", line 135, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\axes\\_base.py\", line 2647, in draw\r\n    mimage._draw_list_compositing_images(renderer, self, artists)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\image.py\", line 135, in _draw_list_compositing_images\r\n    a.draw(renderer)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\artist.py\", line 38, in draw_wrapper\r\n    return draw(artist, renderer, *args, **kwargs)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\collections.py\", line 329, in draw\r\n    self._offset_position)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\backends\\backend_ps.py\", line 492, in draw_path_collection\r\n    offset_position)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\backend_bases.py\", line 245, in draw_path_collection\r\n    self.draw_path(gc0, path, transform, rgbFace)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\backends\\backend_ps.py\", line 414, in draw_path\r\n    self._draw_ps(ps, gc, rgbFace)\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\backends\\backend_ps.py\", line 759, in _draw_ps\r\n    self.set_linedash(*gc.get_dashes())\r\n\r\n  File \"C:\\Users\\mhossein\\Anaconda3\\lib\\site-packages\\matplotlib\\backends\\backend_ps.py\", line 276, in set_linedash\r\n    s = \"[%s] %d setdash\\n\" % (_nums_to_str(*seq), offset)\r\n\r\nTypeError: %d format: a number is required, not NoneType\r\n```\r\n\r\n**Expected outcome**\r\n\r\nThe above snippet works when png extension is used, or when `[7.0, 7.0]` is replaced with `'dashed'`\r\n\r\n**Matplotlib version**\r\n\u003c!--Please specify your platform and versions of the relevant libraries you are using:--\u003e\r\n  * Operating system: windows 7.0\r\n  * Matplotlib version: 3.1.1\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): Qt5Agg\r\n  * Python version: 3.7.1\r\n  * Jupyter version (if applicable):\r\n  * Other libraries: \r\n\r\n\u003c!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda--\u003e\r\n\u003c!--If you installed from conda, please specify which channel you used if not the default--\u003e\r\n\r\n","author":{"url":"https://github.com/Mahdi-Hosseinali","@type":"Person","name":"Mahdi-Hosseinali"},"datePublished":"2019-08-06T20:13:40.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":6},"url":"https://github.com/14996/matplotlib/issues/14996"}