Figure is unpicklable after savefig #6870
Description
import matplotlib.pyplot as plt
import pickle
from io import BytesIO
def test_pickle_after_savefig():
fig = plt.figure()
fig.add_subplot(111)
for fmt in ['pdf', 'png', 'svg']:
fig.savefig(BytesIO(), format=fmt)
try:
pickle.dump(fig, BytesIO())
except:
print('Unpickable after "%s"' % fmt)
raise
test_pickle_after_savefig()>python test_pickle_after_savefig.py
Unpickable after "svg"
Traceback (most recent call last):
File "test_pickle_after_savefig.py", line 16, in <module>
test_pickle_after_savefig()
File "test_pickle_after_savefig.py", line 11, in test_pickle_after_savefig
pickle.dump(fig, BytesIO())
TypeError: cannot serialize '_io.TextIOWrapper' object
I think those warnings from pytest are maybe related:
>py.test -n 4 lib/matplotlib/tests/test_backend_svg.py::test_fill_black_with_alpha
============================= test session starts =============================
platform win32 -- Python 3.5.2, pytest-2.9.2, py-1.4.31, pluggy-0.3.1
rootdir: C:\Working\Repositories\matplotlib, inifile: pytest.ini
plugins: xdist-1.14
gw0 [1] / gw1 [1] / gw2 [1] / gw3 [1]
scheduling tests via LoadScheduling
.sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=0 mode='r' encoding='cp866'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=1 mode='w' encoding='cp866'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=0 mode='r' encoding='cp866'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=0 mode='r' encoding='cp866'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=1 mode='w' encoding='cp866'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=1 mode='w' encoding='cp866'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=0 mode='r' encoding='cp866'>
sys:1: ResourceWarning: unclosed file <_io.TextIOWrapper name=1 mode='w' encoding='cp866'>
With a file name pickle fails in the pdf backend (and svg too):
import matplotlib.pylab as plt
import pickle
from io import BytesIO
def test_pickle_after_savefig2():
fig = plt.figure()
fig.add_subplot(111)
for fmt in ['pdf', 'png', 'svg']:
fig.savefig('test.%s' % fmt, format=fmt)
try:
pickle.dump(fig, BytesIO())
except:
print('Unpickable format is "%s"' % fmt)
raise
test_pickle_after_savefig2()>python test_pickle_after_savefig2.py
Unpickable format is "pdf"
Traceback (most recent call last):
File "test_pickle_after_savefig2.py", line 16, in <module>
test_pickle_after_savefig()
File "test_pickle_after_savefig2.py", line 11, in test_pickle_after_savefig
pickle.dump(fig, BytesIO())
TypeError: cannot serialize '_io.BufferedWriter' object