Ali Sina wrote:
I have Python 3.0 and I'm trying to learn from a pdf document. I followed its
instructions >>but I've encountered a problem in its Pickling chapter. This is
the code I've written:
import pickle, shelve
print('Pickling list.')
variety=['sweet','hot','dill']
shape=['whole','spear','chip']
brand=['Claussen','Heinz','Vlassic']
pickle_file=open('pickles1.dat','w')
pickle.dump(variety, pickle_file)
pickle.dump(shape, pickle_file)
pickle.dump(brand, pickle_file)
pickle_file.close()
print('\nUnpickling list.')
pickle_file=open('pickles1.dat','r')
variety=pickle.load(pickle_file)
shape=pickle.load(pickle_file)
brand=pickle.load(pickle_file)
print(variety,'\n',shape,'\n',brand)
pickle_file.close()
But it gives this error:
Traceback (most recent call last):
File "E:/Python/pickle it.py", line 11, in <module>
pickle.dump(variety, pickle_file)
File "C:\Python31\lib\pickle.py", line 1354, in dump
Pickler(file, protocol, fix_imports=fix_imports).dump(obj)
TypeError: write() argument 1 must be str, not bytes
I read Python Docs but it didn't help me either. I hoping anyone of you could guide
me or >>send the revised code itself. Thank you.
Regards
Three guesses, then a suggestion:
I'd guess that the pdf document you're learning from is aimed at Python
2.x, not Python 3.x
In Python 3, all strings are in Unicode, and there's a distinct type,
bytes, which serves to store non-Unicode versions of strings. How that
fits, I don't know.
I'd upgrade to Python 3.1, Python 3.0 has a lot of known problems.
But I think your real problem is:
the Pickler constructor expects a binary file, so you'll want "wb"
instead of "w" on the open().
With that change, it works for me:
Unpickling list.
['sweet', 'hot', 'dill']
['whole', 'spear', 'chip']
['Claussen', 'Heinz', 'Vlassic']
DaveA
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