Unicode error handling with Python 3's readlines()

Question

I keep getting this error while reading a text file. Is it possible to handle/ignore it and proceed?

UnicodeEncodeError: ‘charmap’ codec can’t decode byte 0x81 in position 7827: character maps to undefined.

Answer 1

In Python 3, pass an appropriate errors= value (such as errors=ignore or errors=replace) on creating your file object (presuming it to be a subclass of io.TextIOWrapper -- and if it isn't, consider wrapping it in one!); also, consider passing a more likely encoding than charmap (when you aren't sure, utf-8 is always a good place to start).

For instance:

f = open('misc-notes.txt', encoding='utf-8', errors='ignore')

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In Python 2, the read() operation simply returns bytes; the trick, then, is decoding them to get them into a string (if you do, in fact, want characters as opposed to bytes). If you don't have a better guess for their real encoding:

your_string.decode('utf-8', 'replace')

...to replace unhandled characters, or

your_string.decode('utf-8', 'ignore')

to simply ignore them.

That said, finding and using their real encoding (rather than guessing utf-8) would be preferred.

Answer 2

You should open the file with a codecs to make sure that the file gets interpreted as UTF8.

import codecs
fd = codecs.open(filename,'r',encoding='utf-8')
data = fd.read()