Python3 UnicodeDecodeError with readlines() method

Question

Trying to create a twitter bot that reads lines and posts them. Using Python3 and tweepy, via a virtualenv on my shared server space. This is the part of the code that seems to have trouble:

#!/foo/env/bin/python3

import re
import tweepy, time, sys

argfile = str(sys.argv[1])

filename=open(argfile, 'r')
f=filename.readlines()
filename.close()

this is the error I get:

UnicodeDecodeError: 'ascii' codec can't decode byte 0xfe in position 0: ordinal not in range(128)

The error specifically points to f=filename.readlines() as the source of the error. Any idea what might be wrong? Thanks.

Answer 1

I think the best answer (in Python 3) is to use the errors= parameter:

with open('evil_unicode.txt', 'r', errors='replace') as f:
    lines = f.readlines()

Proof:

>>> s = b'\xe5abc\nline2\nline3'
>>> with open('evil_unicode.txt','wb') as f:
...     f.write(s)
...
16
>>> with open('evil_unicode.txt', 'r') as f:
...     lines = f.readlines()
...
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/codecs.py", line 319, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe5 in position 0: invalid continuation byte
>>> with open('evil_unicode.txt', 'r', errors='replace') as f:
...     lines = f.readlines()
...
>>> lines
['�abc\n', 'line2\n', 'line3']
>>>

Note that the errors= can be replace or ignore. Here's what ignore looks like:

>>> with open('evil_unicode.txt', 'r', errors='ignore') as f:
...     lines = f.readlines()
...
>>> lines
['abc\n', 'line2\n', 'line3']