Pickle figures from matplotlib
The error with copy_reg was being caused by the write format in the code to pickle the figure, the correct code should include wb rather than w in the write statement as in:
# Save figure handle to disk
import pickle
with open('sinus.pickle', 'wb') as f: # should be 'wb' rather than 'w'
pickle.dump(fig_handle, f)
This was identified based on the copy_reg error and the solution provided in another question ImportError: No module named copy_reg pickle about copy_reg error when pickling.
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Updated on June 12, 2022Comments
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Admin almost 2 years
I am trying to recreate the simple pickle figure example from the question: Saving interactive Matplotlib figures, which is also sourced from Saving Matplotlib Figures Using Pickle. However, when I run the given codes the figures seems to pickle OK, but then I get an error when I try to load the pickled figure. I am running it using Canopy Enthought (v1.6.2.3262), using Matplotlib 1.5.1-1 and Numpy 1.9.2-3 on Python 2.7.3-1. The pickle code is:`
import numpy as np import matplotlib.pyplot as plt import pickle as pl # Plot simple sinus function fig_handle = plt.figure() x = np.linspace(0,2*np.pi) y = np.sin(x) plt.plot(x,y) # Save figure handle to disk pl.dump(fig_handle,file('sinus.pickle','w'))`
The code to load the figure is:
import matplotlib.pyplot as plt import pickle as pl import numpy as np # Load figure from disk and display fig_handle = pl.load(open('sinus.pickle','rb')) fig_handle.show()
and the error I get is:
%run "Z:\EFNHigh_Res\show_picklefig.py" --------------------------------------------------------------------------- ImportError Traceback (most recent call last) Z:\EFNHigh_Res\show_picklefig.py in <module>() 4 5 #plot simple sinus function ----> 6 fig_handle = pl.load(open('Z:\EFNHigh_Res\sinus.pickle','rb')) 7 fig_handle.show() C:\Users\Tom\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.6.2.3262.win-x86_64\lib\pickle.pyc in load(file) 1376 1377 def load(file): -> 1378 return Unpickler(file).load() 1379 1380 def loads(str): C:\Users\Tom\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.6.2.3262.win-x86_64\lib\pickle.pyc in load(self) 856 while 1: 857 key = read(1) --> 858 dispatch[key](self) 859 except _Stop, stopinst: 860 return stopinst.value C:\Users\Tom\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.6.2.3262.win-x86_64\lib\pickle.pyc in load_global(self) 1088 module = self.readline()[:-1] 1089 name = self.readline()[:-1] -> 1090 klass = self.find_class(module, name) 1091 self.append(klass) 1092 dispatch[GLOBAL] = load_global C:\Users\Tom\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.6.2.3262.win-x86_64\lib\pickle.pyc in find_class(self, module, name) 1122 def find_class(self, module, name): 1123 # Subclasses may override this -> 1124 __import__(module) 1125 mod = sys.modules[module] 1126 klass = getattr(mod, name) ImportError: No module named copy_reg
I know that there is a difference between Python 3 and 2, in that file instead of open should be used in the dump (and I presume the pickle load) for Python 2, so I have tried both combinations in the code.
I am unsure what the error is telling me, so I haven't been able to get any further with this, any help on understanding the errors or fixing the problem appreciated.