René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Figure is unpicklable after `savefig`","articleBody":"``` python\nimport matplotlib.pyplot as plt\nimport pickle\nfrom io import BytesIO\n\ndef test_pickle_after_savefig():\n    fig = plt.figure()\n    fig.add_subplot(111)\n    for fmt in ['pdf', 'png', 'svg']:\n        fig.savefig(BytesIO(), format=fmt)\n        try:\n            pickle.dump(fig, BytesIO())\n        except:\n            print('Unpickable after \"%s\"' % fmt)\n            raise\n\ntest_pickle_after_savefig()\n```\n\n```\n\u003epython test_pickle_after_savefig.py\nUnpickable after \"svg\"\nTraceback (most recent call last):\n  File \"test_pickle_after_savefig.py\", line 16, in \u003cmodule\u003e\n    test_pickle_after_savefig()\n  File \"test_pickle_after_savefig.py\", line 11, in test_pickle_after_savefig\n    pickle.dump(fig, BytesIO())\nTypeError: cannot serialize '_io.TextIOWrapper' object\n```\n\nI think those warnings from pytest are maybe related:\n\n```\n\u003epy.test -n 4 lib/matplotlib/tests/test_backend_svg.py::test_fill_black_with_alpha\n============================= test session starts =============================\nplatform win32 -- Python 3.5.2, pytest-2.9.2, py-1.4.31, pluggy-0.3.1\nrootdir: C:\\Working\\Repositories\\matplotlib, inifile: pytest.ini\nplugins: xdist-1.14\ngw0 [1] / gw1 [1] / gw2 [1] / gw3 [1]\nscheduling tests via LoadScheduling\n.sys:1: ResourceWarning: unclosed file \u003c_io.TextIOWrapper name=0 mode='r' encoding='cp866'\u003e\nsys:1: ResourceWarning: unclosed file \u003c_io.TextIOWrapper name=1 mode='w' encoding='cp866'\u003e\nsys:1: ResourceWarning: unclosed file \u003c_io.TextIOWrapper name=0 mode='r' encoding='cp866'\u003e\nsys:1: ResourceWarning: unclosed file \u003c_io.TextIOWrapper name=0 mode='r' encoding='cp866'\u003e\nsys:1: ResourceWarning: unclosed file \u003c_io.TextIOWrapper name=1 mode='w' encoding='cp866'\u003e\nsys:1: ResourceWarning: unclosed file \u003c_io.TextIOWrapper name=1 mode='w' encoding='cp866'\u003e\nsys:1: ResourceWarning: unclosed file \u003c_io.TextIOWrapper name=0 mode='r' encoding='cp866'\u003e\nsys:1: ResourceWarning: unclosed file \u003c_io.TextIOWrapper name=1 mode='w' encoding='cp866'\u003e\n```\n\nWith a file name pickle fails in the pdf backend (and svg too):\n\n``` python\nimport matplotlib.pylab as plt\nimport pickle\nfrom io import BytesIO\n\ndef test_pickle_after_savefig2():\n    fig = plt.figure()\n    fig.add_subplot(111)\n    for fmt in ['pdf', 'png', 'svg']:\n        fig.savefig('test.%s' % fmt, format=fmt)\n        try:\n            pickle.dump(fig, BytesIO())\n        except:\n            print('Unpickable format is \"%s\"' % fmt)\n            raise\n\ntest_pickle_after_savefig2()\n```\n\n```\n\u003epython test_pickle_after_savefig2.py\nUnpickable format is \"pdf\"\nTraceback (most recent call last):\n  File \"test_pickle_after_savefig2.py\", line 16, in \u003cmodule\u003e\n    test_pickle_after_savefig()\n  File \"test_pickle_after_savefig2.py\", line 11, in test_pickle_after_savefig\n    pickle.dump(fig, BytesIO())\nTypeError: cannot serialize '_io.BufferedWriter' object\n```\n","author":{"url":"https://github.com/Kojoley","@type":"Person","name":"Kojoley"},"datePublished":"2016-07-31T18:35:33.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":7},"url":"https://github.com/6870/matplotlib/issues/6870"}