Encoding issues when converting Pyhon 2 to Python 3 (using lmdb)











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I'm trying to convert some code in Python 2 to Python 3. I'm not too familiar with the changes in how encoding works between the two versions of Python, so was not exactly sure how to word the question.



Basically in Python 2 the code looks like this:



image_key = "image_3"
env = lmdb.open(some arguments here)

with env.begin(write=False) as txn:
img_tmp = txn.get(image_key)
img = Image.open(StringIO(img_tmp))


In Python 2, "img_tmp" would be a string object with unreadable characters (printing it gives me a mess: �PNGIHDR � �A�� gAMA ���acHRMz&��� ��u0�`...). And the next line would open the image as a pillow image.



In Python 3, the line txn.get() would give me an error "TypeError: Won't implicitly convert Unicode to bytes; use .encode()" so I I followed the suggestion and converted the line to:



img_tmp = txn.get(img_key.encode())


However, img_tmp is now a bytes object that reads something like this: "b'x89PNGrnx1anx00 ..."



And the next line would no longer open the image. Any suggestions on how to change the code to get it to work?










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  • I was able to generate a string object that looks similar to what I get in Python 2 using txn.get(image_key.encode()).decode("ascii", "replace") or txn.get(image_key.encode()).decode("utf-8", "replace") However i still can't open the pillow image.
    – matohak
    Nov 9 at 15:08

















up vote
1
down vote

favorite












I'm trying to convert some code in Python 2 to Python 3. I'm not too familiar with the changes in how encoding works between the two versions of Python, so was not exactly sure how to word the question.



Basically in Python 2 the code looks like this:



image_key = "image_3"
env = lmdb.open(some arguments here)

with env.begin(write=False) as txn:
img_tmp = txn.get(image_key)
img = Image.open(StringIO(img_tmp))


In Python 2, "img_tmp" would be a string object with unreadable characters (printing it gives me a mess: �PNGIHDR � �A�� gAMA ���acHRMz&��� ��u0�`...). And the next line would open the image as a pillow image.



In Python 3, the line txn.get() would give me an error "TypeError: Won't implicitly convert Unicode to bytes; use .encode()" so I I followed the suggestion and converted the line to:



img_tmp = txn.get(img_key.encode())


However, img_tmp is now a bytes object that reads something like this: "b'x89PNGrnx1anx00 ..."



And the next line would no longer open the image. Any suggestions on how to change the code to get it to work?










share|improve this question






















  • I was able to generate a string object that looks similar to what I get in Python 2 using txn.get(image_key.encode()).decode("ascii", "replace") or txn.get(image_key.encode()).decode("utf-8", "replace") However i still can't open the pillow image.
    – matohak
    Nov 9 at 15:08















up vote
1
down vote

favorite









up vote
1
down vote

favorite











I'm trying to convert some code in Python 2 to Python 3. I'm not too familiar with the changes in how encoding works between the two versions of Python, so was not exactly sure how to word the question.



Basically in Python 2 the code looks like this:



image_key = "image_3"
env = lmdb.open(some arguments here)

with env.begin(write=False) as txn:
img_tmp = txn.get(image_key)
img = Image.open(StringIO(img_tmp))


In Python 2, "img_tmp" would be a string object with unreadable characters (printing it gives me a mess: �PNGIHDR � �A�� gAMA ���acHRMz&��� ��u0�`...). And the next line would open the image as a pillow image.



In Python 3, the line txn.get() would give me an error "TypeError: Won't implicitly convert Unicode to bytes; use .encode()" so I I followed the suggestion and converted the line to:



img_tmp = txn.get(img_key.encode())


However, img_tmp is now a bytes object that reads something like this: "b'x89PNGrnx1anx00 ..."



And the next line would no longer open the image. Any suggestions on how to change the code to get it to work?










share|improve this question













I'm trying to convert some code in Python 2 to Python 3. I'm not too familiar with the changes in how encoding works between the two versions of Python, so was not exactly sure how to word the question.



Basically in Python 2 the code looks like this:



image_key = "image_3"
env = lmdb.open(some arguments here)

with env.begin(write=False) as txn:
img_tmp = txn.get(image_key)
img = Image.open(StringIO(img_tmp))


In Python 2, "img_tmp" would be a string object with unreadable characters (printing it gives me a mess: �PNGIHDR � �A�� gAMA ���acHRMz&��� ��u0�`...). And the next line would open the image as a pillow image.



In Python 3, the line txn.get() would give me an error "TypeError: Won't implicitly convert Unicode to bytes; use .encode()" so I I followed the suggestion and converted the line to:



img_tmp = txn.get(img_key.encode())


However, img_tmp is now a bytes object that reads something like this: "b'x89PNGrnx1anx00 ..."



And the next line would no longer open the image. Any suggestions on how to change the code to get it to work?







python python-3.x python-2.7 lmdb






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asked Nov 9 at 15:00









matohak

244




244












  • I was able to generate a string object that looks similar to what I get in Python 2 using txn.get(image_key.encode()).decode("ascii", "replace") or txn.get(image_key.encode()).decode("utf-8", "replace") However i still can't open the pillow image.
    – matohak
    Nov 9 at 15:08




















  • I was able to generate a string object that looks similar to what I get in Python 2 using txn.get(image_key.encode()).decode("ascii", "replace") or txn.get(image_key.encode()).decode("utf-8", "replace") However i still can't open the pillow image.
    – matohak
    Nov 9 at 15:08


















I was able to generate a string object that looks similar to what I get in Python 2 using txn.get(image_key.encode()).decode("ascii", "replace") or txn.get(image_key.encode()).decode("utf-8", "replace") However i still can't open the pillow image.
– matohak
Nov 9 at 15:08






I was able to generate a string object that looks similar to what I get in Python 2 using txn.get(image_key.encode()).decode("ascii", "replace") or txn.get(image_key.encode()).decode("utf-8", "replace") However i still can't open the pillow image.
– matohak
Nov 9 at 15:08














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You’re almost there: just use BytesIO instead of StringIO, since your binary data is a bytes and not a str.






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    up vote
    1
    down vote



    accepted










    You’re almost there: just use BytesIO instead of StringIO, since your binary data is a bytes and not a str.






    share|improve this answer

























      up vote
      1
      down vote



      accepted










      You’re almost there: just use BytesIO instead of StringIO, since your binary data is a bytes and not a str.






      share|improve this answer























        up vote
        1
        down vote



        accepted







        up vote
        1
        down vote



        accepted






        You’re almost there: just use BytesIO instead of StringIO, since your binary data is a bytes and not a str.






        share|improve this answer












        You’re almost there: just use BytesIO instead of StringIO, since your binary data is a bytes and not a str.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 9 at 22:21









        Davis Herring

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