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How to decode chars in Python respectively?

I have tried this problem
# -*- coding: utf-8 -*-
s = "Ñ ÑÑÑаÑ! Ð½ÐµÑ Ñил"
e = s.encode('ascii')
print e
but it gives me this error.
Traceback (most recent call last):
File "C:/Users/username/Desktop/unicode.py", line 3, in <module>
e = s.encode('ascii')
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 0: ordinal not in range(128)
How do I get the text to be readable? I have been trying for hours! Not sure how to fix this. Any help would be greatly appreciated!

You have a whole slew of problems here.
First, you've stuck Unicode characters into a str literal instead of a unicode literal. That's almost always a bad idea.
Second, you've called encode on a str. But encode is for converting unicode to str.* In order to do that, Python has to first decode your str to a unicode so that it can call encode on it. And if you force Python to decode for you without telling it which codec to use, it will use sys.getdefaultencoding(), which is almost never what you want. (In particular, it's not going to be UTF-8 just because your source encoding is.)
You can fix those first two problems just by adding one letter:
s = u"Ñ ÑÑÑаÑ! Ð½ÐµÑ Ñил"
But it's still not going to work. Why? Because you're asking it to encode non-ASCII characters into the ASCII character set. Which is impossible. So it's going to call the error handler. Since you didn't specify an error handler, you get the default, called strict. As the name implies, strict raises an exception when you ask it do something impossible.
There are other error handlers—see the str.encode docs for a full list. I'm not sure what output you were expecting, but you can get backslash-escaped text, or text with all the non-ASCII characters replaced by ?s, or a few other possibilities. For example:
e = s.encode('ascii', 'replace')
Of course if you didn't actually want ASCII, but rather UTF-8, then everything is easy: just tell Python you want UTF-8 instead of ASCII:
e = s.encode('utf-8')
* There are a few special codecs, like hex and gzip, that convert str to str, unicode to unicode, or str to unicode, but ascii isn't one of them.

Converting Unicode to in python [duplicate]

This question already has an answer here:
Closed 10 years ago.
Possible Duplicate:
Convert Unicode to UTF-8 Python
I'm a very new python programmer, working on my first script. the script pulls in text from a plist string, then does some things to it, then packages it up as an HTML email.
from a few of the entries, I'm getting the dreaded Unicode "outside ordinal 128" error.
Having read as much as I can find about encoding, and decoding, I know that it is important for me to get the encoded, but I'm having a difficult time understanding when or how exactly to do this.
The offending variable is first pulled in using plistlib, and converted to HTML from markdown, like this:
entry = result['Entry Text']
donotecontent = markdown2.markdown(entry)
Later, it is put in the email like this:
html = donotecontent + '<br /><br />' + var3
part1 = MIMEText(html, 'html')
msg.attach(part1)
My question is, what is the best way for me to make sure that Unicode characters in this content doesn't cause this to throw an error. I prefer not to ignore the characters.

Sorry for my broken english. I am speaking Chinese/Japanese, and using CJK characters everyday.
Ceron solved almost of this problem, thus I won't talk about how to use encode()/decode() again.
When we use str() to cast any unicode object, it will encode unicode string to bytedata; when we use unicode() to cast str object, it will decode bytedata to unicode character.
And, the encoding must be what returned from sys.getdefaultencoding().
In default, sys.getdefaultencoding() return 'ascii' by default, the encoding/decoding exception may be thrown when doing str()/unicode() casting.
If you want to do str <-> unicode conversion by str() or unicode(), and also, implicity encoding/decoding with 'utf-8', you can execute the following statement:
import sys # sys.setdefaultencoding is cancelled by site.py
reload(sys) # to re-enable sys.setdefaultencoding()
sys.setdefaultencoding('utf-8')
and it will cause later execution of str() and unicode() convert any basestring object with encoding utf-8.
However, I would prefer to use encode()/decode() explicitly, because it makes code maintenance easier for me.

Assuming you're using Python 2.x, remember: there are two types of strings: str and unicode. str are byte strings, whereas unicode are unicode strings. unicode strings can be used to represent text in any language, but to store text in a computer or to send it via email, you need to represent that text using bytes. To represent text using bytes, you need an coding format. There are many coding formats, Python uses ascii by default, but ascii can only represent a few characters, mostly english letters. If you try to encode a text with other letters using ascii, you will get the famous "outside ordinal 128". For example:
>>> u'Cerón'.encode('ascii')
Traceback (most recent call last):
File "<input>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode character u'\xf3' in position 3:
ordinal not in range(128)
The same happens if you use str(u'Cerón'), because Python uses ascii by default to convert unicode to str.
To make this work, you have to use a different coding format. UTF-8 is a coding format that can express any unicode text as bytes. To convert the u'Cerón' unicode string to bytes you have to use:
>>> u'Cerón'.encode('utf-8')
'Cer\xc3\xb3n'
No errors this time.
Now, back to your email problem. I can see that you're using MIMEText, which accepts an already encoded str argument, in your case is the html variable. MIMEText also accepts an argument specifying what kind of encoding is being used. So, in your case, if html is a unicode string, you have to encode it as utf-8 and pass the charset parameter too (because HTMLText uses ascii by default):
part1 = MIMEText(html.encode('utf-8'), 'html', 'utf-8')
But be careful, because if html is already a str instead of unicode, then the encoding will fail. This is one of the problems of Python 2.x, it allows you to encode an already encoded string but it throws an error.
Another problem to add to the list is that utf-8 is compatible with ascii characters, and Python will always try to automatically encode/decode strings using ascii. If you're not properly encoding your strings, but you only use ascii characters, things will work fine. However, if for some reason some non-ascii characters slips into your message, you will get the error, this makes errors harder to detect.

Remember: You can't decode a unicode, and you can't encode a str
>>> u"\xa0".decode("ascii", "ignore")
Traceback (most recent call last):
File "<pyshell#7>", line 1, in <module>
u"\xa0".decode("ascii", "ignore")
UnicodeEncodeError: 'ascii' codec can't encode character u'\xa0' in position 0: ordinal not in range(128)
>>> "\xc2".encode("ascii", "ignore")
Traceback (most recent call last):
File "<pyshell#6>", line 1, in <module>
"\xc2".encode("ascii", "ignore")
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2 in position 0: ordinal not in range(128)
Checkout this excellent tutorial

Printing escaped Unicode in Python

>>> s = 'auszuschließen'
>>> print(s.encode('ascii', errors='xmlcharrefreplace'))
b'auszuschließen'
>>> print(str(s.encode('ascii', errors='xmlcharrefreplace'), 'ascii'))
auszuschließen
Is there a prettier way to print any string without the b''?
EDIT:
I'm just trying to print escaped characters from Python, and my only gripe is that Python adds "b''" when i do that.
If i wanted to see the actual character in a dumb terminal like Windows 7's, then i get this:
Traceback (most recent call last):
File "Mailgen.py", line 378, in <module>
marked_copy = mark_markup(language_column, item_row)
File "Mailgen.py", line 210, in mark_markup
print("TP: %r" % "".join(to_print))
File "c:\python32\lib\encodings\cp437.py", line 19, in encode
return codecs.charmap_encode(input,self.errors,encoding_map)[0]
UnicodeEncodeError: 'charmap' codec can't encode character '\u2026' in position 29: character maps to <undefined>

>>> s='auszuschließen…'
>>> s
'auszuschließen…'
>>> print(s)
auszuschließen…
>>> b=s.encode('ascii','xmlcharrefreplace')
>>> b
b'auszuschließen…'
>>> print(b)
b'auszuschließen…'
>>> b.decode()
'auszuschließen…'
>>> print(b.decode())
auszuschließen…
You start out with a Unicode string. Encoding it to ascii creates a bytes object with the characters you want. Python won't print it without converting it back into a string and the default conversion puts in the b and quotes. Using decode explicitly converts it back to a string; the default encoding is utf-8, and since your bytes only consist of ascii which is a subset of utf-8 it is guaranteed to work.

To see ascii representation (like repr() on Python 2) for debugging:
print(ascii('auszuschließen…'))
# -> 'auszuschlie\xdfen\u2026'
To print bytes:
sys.stdout.buffer.write('auszuschließen…'.encode('ascii', 'xmlcharrefreplace'))
# -> auszuschließen…

Not all terminals can handle more than some sort of 8-bit character set, that's true. But they won't handle that no matter what you do, really.
Printing a Unicode string will, assuming that your OS set's up the terminal properly, result in the best result possible, which means that the characters that the terminal can not print will be replaced with some character, like a question mark or similar. Doing that translation yourself will not really improve things.
Update:
Since you want to know what characters are in the string, you actually want to know the Unicode codes for them, or the XML equivalent in this case. That's more inspecting than printing, and then usually the b'' part isn't a problem per se.
But you can get rid of it easily and hackily like so:
print(repr(s.encode('ascii', errors='xmlcharrefreplace'))[2:-1])

Since you're using Python 3, you're afforded the ability to write print(s) to the console.
I can agree that, depending on the console, it may not be able to print properly, but I would imagine that most modern OSes since 2006 can handle Unicode strings without too much of an issue. I'd encourage you to give it a try and see if it works.
Alternatively, you can enforce a coding by placing this before any lines in a file (similar to a shebang):
# -*- coding: utf-8 -*-
This will force the interpreter to render it as UTF-8.

Double-decoding unicode in python

I am working against an application that seems keen on returning, what I believe to be, double UTF-8 encoded strings.
I send the string u'XüYß' encoded using UTF-8, thus becoming X\u00fcY\u00df (equal to X\xc3\xbcY\xc3\x9f).
The server should simply echo what I sent it, yet returns the following: X\xc3\x83\xc2\xbcY\xc3\x83\xc2\x9f (should be X\xc3\xbcY\xc3\x9f). If I decode it using str.decode('utf-8') becomes u'X\xc3\xbcY\xc3\x9f', which looks like a ... unicode-string, containing the original string encoded using UTF-8.
But Python won't let me decode a unicode string without re-encoding it first - which fails for some reason, that escapes me:
>>> ret = 'X\xc3\x83\xc2\xbcY\xc3\x83\xc2\x9f'.decode('utf-8')
>>> ret
u'X\xc3\xbcY\xc3\x9f'
>>> ret.decode('utf-8')
# Throws UnicodeEncodeError: 'ascii' codec can't encode ...
How do I persuade Python to re-decode the string? - and/or is there any (practical) way of debugging what's actually in the strings, without passing it though all the implicit conversion print uses?
(And yes, I have reported this behaviour with the developers of the server-side.)

ret.decode() tries implicitly to encode ret with the system encoding - in your case ascii.
If you explicitly encode the unicode string, you should be fine. There is a builtin encoding that does what you need:
>>> 'X\xc3\xbcY\xc3\x9f'.encode('raw_unicode_escape').decode('utf-8')
'XüYß'
Really, .encode('latin1') (or cp1252) would be OK, because that's what the server is almost cerainly using. The raw_unicode_escape codec will just give you something recognizable at the end instead of raising an exception:
>>> '€\xe2\x82\xac'.encode('raw_unicode_escape').decode('utf8')
'\\u20ac€'
>>> '€\xe2\x82\xac'.encode('latin1').decode('utf8')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'latin-1' codec can't encode character '\u20ac' in position 0: ordinal not in range(256)
In case you run into this sort of mixed data, you can use the codec again, to normalize everything:
>>> '€\xe2\x82\xac'.encode('raw_unicode_escape').decode('utf8')
'\\u20ac€'
>>> '\\u20ac€'.encode('raw_unicode_escape')
b'\\u20ac\\u20ac'
>>> '\\u20ac€'.encode('raw_unicode_escape').decode('raw_unicode_escape')
'€€'

What you want is the encoding where Unicode code point X is encoded to the same byte value X. For code points inside 0-255 you have this in the latin-1 encoding:
def double_decode(bstr):
return bstr.decode("utf-8").encode("latin-1").decode("utf-8")

Don't use this! Use #hop's solution.
My nasty hack: (cringe! but quietly. It's not my fault, it's the server developers' fault)
def double_decode_unicode(s, encoding='utf-8'):
return ''.join(chr(ord(c)) for c in s.decode(encoding)).decode(encoding)
Then,
>>> double_decode_unicode('X\xc3\x83\xc2\xbcY\xc3\x83\xc2\x9f')
u'X\xfcY\xdf'
>>> print _
XüYß

Here's a little script that might help you, doubledecode.py --
https://gist.github.com/1282752

SQLite, python, unicode, and non-utf data

I started by trying to store strings in sqlite using python, and got the message:
sqlite3.ProgrammingError: You must
not use 8-bit bytestrings unless you
use a text_factory that can interpret
8-bit bytestrings (like text_factory =
str). It is highly recommended that
you instead just switch your
application to Unicode strings.
Ok, I switched to Unicode strings. Then I started getting the message:
sqlite3.OperationalError: Could not
decode to UTF-8 column 'tag_artist'
with text 'Sigur Rós'
when trying to retrieve data from the db. More research and I started encoding it in utf8, but then 'Sigur Rós' starts looking like 'Sigur Rós'
note: My console was set to display in 'latin_1' as #John Machin pointed out.
What gives? After reading this, describing exactly the same situation I'm in, it seems as if the advice is to ignore the other advice and use 8-bit bytestrings after all.
I didn't know much about unicode and utf before I started this process. I've learned quite a bit in the last couple hours, but I'm still ignorant of whether there is a way to correctly convert 'ó' from latin-1 to utf-8 and not mangle it. If there isn't, why would sqlite 'highly recommend' I switch my application to unicode strings?
I'm going to update this question with a summary and some example code of everything I've learned in the last 24 hours so that someone in my shoes can have an easy(er) guide. If the information I post is wrong or misleading in any way please tell me and I'll update, or one of you senior guys can update.
Summary of answers
Let me first state the goal as I understand it. The goal in processing various encodings, if you are trying to convert between them, is to understand what your source encoding is, then convert it to unicode using that source encoding, then convert it to your desired encoding. Unicode is a base and encodings are mappings of subsets of that base. utf_8 has room for every character in unicode, but because they aren't in the same place as, for instance, latin_1, a string encoded in utf_8 and sent to a latin_1 console will not look the way you expect. In python the process of getting to unicode and into another encoding looks like:
str.decode('source_encoding').encode('desired_encoding')
or if the str is already in unicode
str.encode('desired_encoding')
For sqlite I didn't actually want to encode it again, I wanted to decode it and leave it in unicode format. Here are four things you might need to be aware of as you try to work with unicode and encodings in python.
The encoding of the string you want to work with, and the encoding you want to get it to.
The system encoding.
The console encoding.
The encoding of the source file
Elaboration:
(1) When you read a string from a source, it must have some encoding, like latin_1 or utf_8. In my case, I'm getting strings from filenames, so unfortunately, I could be getting any kind of encoding. Windows XP uses UCS-2 (a Unicode system) as its native string type, which seems like cheating to me. Fortunately for me, the characters in most filenames are not going to be made up of more than one source encoding type, and I think all of mine were either completely latin_1, completely utf_8, or just plain ascii (which is a subset of both of those). So I just read them and decoded them as if they were still in latin_1 or utf_8. It's possible, though, that you could have latin_1 and utf_8 and whatever other characters mixed together in a filename on Windows. Sometimes those characters can show up as boxes, other times they just look mangled, and other times they look correct (accented characters and whatnot). Moving on.
(2) Python has a default system encoding that gets set when python starts and can't be changed during runtime. See here for details. Dirty summary ... well here's the file I added:
\# sitecustomize.py
\# this file can be anywhere in your Python path,
\# but it usually goes in ${pythondir}/lib/site-packages/
import sys
sys.setdefaultencoding('utf_8')
This system encoding is the one that gets used when you use the unicode("str") function without any other encoding parameters. To say that another way, python tries to decode "str" to unicode based on the default system encoding.
(3) If you're using IDLE or the command-line python, I think that your console will display according to the default system encoding. I am using pydev with eclipse for some reason, so I had to go into my project settings, edit the launch configuration properties of my test script, go to the Common tab, and change the console from latin-1 to utf-8 so that I could visually confirm what I was doing was working.
(4) If you want to have some test strings, eg
test_str = "ó"
in your source code, then you will have to tell python what kind of encoding you are using in that file. (FYI: when I mistyped an encoding I had to ctrl-Z because my file became unreadable.) This is easily accomplished by putting a line like so at the top of your source code file:
# -*- coding: utf_8 -*-
If you don't have this information, python attempts to parse your code as ascii by default, and so:
SyntaxError: Non-ASCII character '\xf3' in file _redacted_ on line 81, but no encoding declared; see http://www.python.org/peps/pep-0263.html for details
Once your program is working correctly, or, if you aren't using python's console or any other console to look at output, then you will probably really only care about #1 on the list. System default and console encoding are not that important unless you need to look at output and/or you are using the builtin unicode() function (without any encoding parameters) instead of the string.decode() function. I wrote a demo function I will paste into the bottom of this gigantic mess that I hope correctly demonstrates the items in my list. Here is some of the output when I run the character 'ó' through the demo function, showing how various methods react to the character as input. My system encoding and console output are both set to utf_8 for this run:
'�' = original char <type 'str'> repr(char)='\xf3'
'?' = unicode(char) ERROR: 'utf8' codec can't decode byte 0xf3 in position 0: unexpected end of data
'ó' = char.decode('latin_1') <type 'unicode'> repr(char.decode('latin_1'))=u'\xf3'
'?' = char.decode('utf_8') ERROR: 'utf8' codec can't decode byte 0xf3 in position 0: unexpected end of data
Now I will change the system and console encoding to latin_1, and I get this output for the same input:
'ó' = original char <type 'str'> repr(char)='\xf3'
'ó' = unicode(char) <type 'unicode'> repr(unicode(char))=u'\xf3'
'ó' = char.decode('latin_1') <type 'unicode'> repr(char.decode('latin_1'))=u'\xf3'
'?' = char.decode('utf_8') ERROR: 'utf8' codec can't decode byte 0xf3 in position 0: unexpected end of data
Notice that the 'original' character displays correctly and the builtin unicode() function works now.
Now I change my console output back to utf_8.
'�' = original char <type 'str'> repr(char)='\xf3'
'�' = unicode(char) <type 'unicode'> repr(unicode(char))=u'\xf3'
'�' = char.decode('latin_1') <type 'unicode'> repr(char.decode('latin_1'))=u'\xf3'
'?' = char.decode('utf_8') ERROR: 'utf8' codec can't decode byte 0xf3 in position 0: unexpected end of data
Here everything still works the same as last time but the console can't display the output correctly. Etc. The function below also displays more information that this and hopefully would help someone figure out where the gap in their understanding is. I know all this information is in other places and more thoroughly dealt with there, but I hope that this would be a good kickoff point for someone trying to get coding with python and/or sqlite. Ideas are great but sometimes source code can save you a day or two of trying to figure out what functions do what.
Disclaimers: I'm no encoding expert, I put this together to help my own understanding. I kept building on it when I should have probably started passing functions as arguments to avoid so much redundant code, so if I can I'll make it more concise. Also, utf_8 and latin_1 are by no means the only encoding schemes, they are just the two I was playing around with because I think they handle everything I need. Add your own encoding schemes to the demo function and test your own input.
One more thing: there are apparently crazy application developers making life difficult in Windows.
#!/usr/bin/env python
# -*- coding: utf_8 -*-
import os
import sys
def encodingDemo(str):
validStrings = ()
try:
print "str =",str,"{0} repr(str) = {1}".format(type(str), repr(str))
validStrings += ((str,""),)
except UnicodeEncodeError as ude:
print "Couldn't print the str itself because the console is set to an encoding that doesn't understand some character in the string. See error:\n\t",
print ude
try:
x = unicode(str)
print "unicode(str) = ",x
validStrings+= ((x, " decoded into unicode by the default system encoding"),)
except UnicodeDecodeError as ude:
print "ERROR. unicode(str) couldn't decode the string because the system encoding is set to an encoding that doesn't understand some character in the string."
print "\tThe system encoding is set to {0}. See error:\n\t".format(sys.getdefaultencoding()),
print ude
except UnicodeEncodeError as uee:
print "ERROR. Couldn't print the unicode(str) because the console is set to an encoding that doesn't understand some character in the string. See error:\n\t",
print uee
try:
x = str.decode('latin_1')
print "str.decode('latin_1') =",x
validStrings+= ((x, " decoded with latin_1 into unicode"),)
try:
print "str.decode('latin_1').encode('utf_8') =",str.decode('latin_1').encode('utf_8')
validStrings+= ((x, " decoded with latin_1 into unicode and encoded into utf_8"),)
except UnicodeDecodeError as ude:
print "The string was decoded into unicode using the latin_1 encoding, but couldn't be encoded into utf_8. See error:\n\t",
print ude
except UnicodeDecodeError as ude:
print "Something didn't work, probably because the string wasn't latin_1 encoded. See error:\n\t",
print ude
except UnicodeEncodeError as uee:
print "ERROR. Couldn't print the str.decode('latin_1') because the console is set to an encoding that doesn't understand some character in the string. See error:\n\t",
print uee
try:
x = str.decode('utf_8')
print "str.decode('utf_8') =",x
validStrings+= ((x, " decoded with utf_8 into unicode"),)
try:
print "str.decode('utf_8').encode('latin_1') =",str.decode('utf_8').encode('latin_1')
except UnicodeDecodeError as ude:
print "str.decode('utf_8').encode('latin_1') didn't work. The string was decoded into unicode using the utf_8 encoding, but couldn't be encoded into latin_1. See error:\n\t",
validStrings+= ((x, " decoded with utf_8 into unicode and encoded into latin_1"),)
print ude
except UnicodeDecodeError as ude:
print "str.decode('utf_8') didn't work, probably because the string wasn't utf_8 encoded. See error:\n\t",
print ude
except UnicodeEncodeError as uee:
print "ERROR. Couldn't print the str.decode('utf_8') because the console is set to an encoding that doesn't understand some character in the string. See error:\n\t",uee
print
print "Printing information about each character in the original string."
for char in str:
try:
print "\t'" + char + "' = original char {0} repr(char)={1}".format(type(char), repr(char))
except UnicodeDecodeError as ude:
print "\t'?' = original char {0} repr(char)={1} ERROR PRINTING: {2}".format(type(char), repr(char), ude)
except UnicodeEncodeError as uee:
print "\t'?' = original char {0} repr(char)={1} ERROR PRINTING: {2}".format(type(char), repr(char), uee)
print uee
try:
x = unicode(char)
print "\t'" + x + "' = unicode(char) {1} repr(unicode(char))={2}".format(x, type(x), repr(x))
except UnicodeDecodeError as ude:
print "\t'?' = unicode(char) ERROR: {0}".format(ude)
except UnicodeEncodeError as uee:
print "\t'?' = unicode(char) {0} repr(char)={1} ERROR PRINTING: {2}".format(type(x), repr(x), uee)
try:
x = char.decode('latin_1')
print "\t'" + x + "' = char.decode('latin_1') {1} repr(char.decode('latin_1'))={2}".format(x, type(x), repr(x))
except UnicodeDecodeError as ude:
print "\t'?' = char.decode('latin_1') ERROR: {0}".format(ude)
except UnicodeEncodeError as uee:
print "\t'?' = char.decode('latin_1') {0} repr(char)={1} ERROR PRINTING: {2}".format(type(x), repr(x), uee)
try:
x = char.decode('utf_8')
print "\t'" + x + "' = char.decode('utf_8') {1} repr(char.decode('utf_8'))={2}".format(x, type(x), repr(x))
except UnicodeDecodeError as ude:
print "\t'?' = char.decode('utf_8') ERROR: {0}".format(ude)
except UnicodeEncodeError as uee:
print "\t'?' = char.decode('utf_8') {0} repr(char)={1} ERROR PRINTING: {2}".format(type(x), repr(x), uee)
print
x = 'ó'
encodingDemo(x)
Much thanks for the answers below and especially to #John Machin for answering so thoroughly.

I'm still ignorant of whether there is a way to correctly convert 'ó' from latin-1 to utf-8 and not mangle it
repr() and unicodedata.name() are your friends when it comes to debugging such problems:
>>> oacute_latin1 = "\xF3"
>>> oacute_unicode = oacute_latin1.decode('latin1')
>>> oacute_utf8 = oacute_unicode.encode('utf8')
>>> print repr(oacute_latin1)
'\xf3'
>>> print repr(oacute_unicode)
u'\xf3'
>>> import unicodedata
>>> unicodedata.name(oacute_unicode)
'LATIN SMALL LETTER O WITH ACUTE'
>>> print repr(oacute_utf8)
'\xc3\xb3'
>>>
If you send oacute_utf8 to a terminal that is set up for latin1, you will get A-tilde followed by superscript-3.
I switched to Unicode strings.
What are you calling Unicode strings? UTF-16?
What gives? After reading this, describing exactly the same situation I'm in, it seems as if the advice is to ignore the other advice and use 8-bit bytestrings after all.
I can't imagine how it seems so to you. The story that was being conveyed was that unicode objects in Python and UTF-8 encoding in the database were the way to go. However Martin answered the original question, giving a method ("text factory") for the OP to be able to use latin1 -- this did NOT constitute a recommendation!
Update in response to these further questions raised in a comment:
I didn't understand that the unicode characters still contained an implicit encoding. Am I saying that right?
No. An encoding is a mapping between Unicode and something else, and vice versa. A Unicode character doesn't have an encoding, implicit or otherwise.
It looks to me like unicode("\xF3") and "\xF3".decode('latin1') are the same when evaluated with repr().
Say what? It doesn't look like it to me:
>>> unicode("\xF3")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xf3 in position 0: ordinal
not in range(128)
>>> "\xF3".decode('latin1')
u'\xf3'
>>>
Perhaps you meant: u'\xf3' == '\xF3'.decode('latin1') ... this is certainly true.
It is also true that unicode(str_object, encoding) does the same as str_object.decode(encoding) ... including blowing up when an inappropriate encoding is supplied.
Is that a happy circumstance
That the first 256 characters in Unicode are the same, code for code, as the 256 characters in latin1 is a good idea. Because all 256 possible latin1 characters are mapped to Unicode, it means that ANY 8-bit byte, ANY Python str object can be decoded into unicode without an exception being raised. This is as it should be.
However there exist certain persons who confuse two quite separate concepts: "my script runs to completion without any exceptions being raised" and "my script is error-free". To them, latin1 is "a snare and a delusion".
In other words, if you have a file that's actually encoded in cp1252 or gbk or koi8-u or whatever and you decode it using latin1, the resulting Unicode will be utter rubbish and Python (or any other language) will not flag an error -- it has no way of knowing that you have commited a silliness.
or is unicode("str") going to always return the correct decoding?
Just like that, with the default encoding being ascii, it will return the correct unicode if the file is actually encoded in ASCII. Otherwise, it'll blow up.
Similarly, if you specify the correct encoding, or one that's a superset of the correct encoding, you'll get the correct result. Otherwise you'll get gibberish or an exception.
In short: the answer is no.
If not, when I receive a python str that has any possible character set in it, how do I know how to decode it?
If the str object is a valid XML document, it will be specified up front. Default is UTF-8.
If it's a properly constructed web page, it should be specified up front (look for "charset"). Unfortunately many writers of web pages lie through their teeth (ISO-8859-1 aka latin1, should be Windows-1252 aka cp1252; don't waste resources trying to decode gb2312, use gbk instead). You can get clues from the nationality/language of the website.
UTF-8 is always worth trying. If the data is ascii, it'll work fine, because ascii is a subset of utf8. A string of text that has been written using non-ascii characters and has been encoded in an encoding other than utf8 will almost certainly fail with an exception if you try to decode it as utf8.
All of the above heuristics and more and a lot of statistics are encapsulated in chardet, a module for guessing the encoding of arbitrary files. It usually works well. However you can't make software idiot-proof. For example, if you concatenate data files written some with encoding A and some with encoding B, and feed the result to chardet, the answer is likely to be encoding C with a reduced level of confidence e.g. 0.8. Always check the confidence part of the answer.
If all else fails:
(1) Try asking here, with a small sample from the front of your data ... print repr(your_data[:400]) ... and whatever collateral info about its provenance that you have.
(2) Recent Russian research into techniques for recovering forgotten passwords appears to be quite applicable to deducing unknown encodings.
Update 2 BTW, isn't it about time you opened up another question ?-)
One more thing: there are apparently characters that Windows uses as Unicode for certain characters that aren't the correct Unicode for that character, so you may have to map those characters to the correct ones if you want to use them in other programs that are expecting those characters in the right spot.
It's not Windows that's doing it; it's a bunch of crazy application developers. You might have more understandably not paraphrased but quoted the opening paragraph of the effbot article that you referred to:
Some applications add CP1252 (Windows, Western Europe) characters to documents marked up as ISO 8859-1 (Latin 1) or other encodings. These characters are not valid ISO-8859-1 characters, and may cause all sorts of problems in processing and display applications.
Background:
The range U+0000 to U+001F inclusive is designated in Unicode as "C0 Control Characters". These exist also in ASCII and latin1, with the same meanings. They include such familar things as carriage return, line feed, bell, backspace, tab, and others that are used rarely.
The range U+0080 to U+009F inclusive is designated in Unicode as "C1 Control Characters". These exist also in latin1, and include 32 characters that nobody outside unicode.org can imagine any possible use for.
Consequently, if you run a character frequency count on your unicode or latin1 data, and you find any characters in that range, your data is corrupt. There is no universal solution; it depends on how it became corrupted. The characters may have the same meaning as the cp1252 characters at the same positions, and thus the effbot's solution will work. In another case that I've been looking at recently, the dodgy characters appear to have been caused by concatenating text files encoded in UTF-8 and another encoding which needed to be deduced based on letter frequencies in the (human) language the files were written in.

UTF-8 is the default encoding of SQLite databases. This shows up in situations like "SELECT CAST(x'52C3B373' AS TEXT);". However, the SQLite C library doesn't actually check whether a string inserted into a DB is valid UTF-8.
If you insert a Python unicode object (or str object in 3.x), the Python sqlite3 library will automatically convert it to UTF-8. But if you insert a str object, it will just assume the string is UTF-8, because Python 2.x "str" doesn't know its encoding. This is one reason to prefer Unicode strings.
However, it doesn't help you if your data is broken to begin with.
To fix your data, do
db.create_function('FIXENCODING', 1, lambda s: str(s).decode('latin-1'))
db.execute("UPDATE TheTable SET TextColumn=FIXENCODING(CAST(TextColumn AS BLOB))")
for every text column in your database.

I fixed this pysqlite problem by setting:
conn.text_factory = lambda x: unicode(x, 'utf-8', 'ignore')
By default text_factory is set to unicode(), which will use the current default encoding (ascii on my machine)

Of course there is. But your data is already broken in the database, so you'll need to fix it:
>>> print u'Sigur Rós'.encode('latin-1').decode('utf-8')
Sigur Rós

My unicode problems with Python 2.x (Python 2.7.6 to be specific) fixed this:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
import sys
reload(sys)
sys.setdefaultencoding('utf-8')
It also solved the error you are mentioning right at the beginning of the post:
sqlite3.ProgrammingError: You must not use 8-bit bytestrings unless
...
EDIT
sys.setdefaultencoding is a dirty hack. Yes, it can solve UTF-8 issues, but everything comes with a price. For more details refer to following links:
Why sys.setdefaultencoding() will break code
Why we need sys.setdefaultencoding(“utf-8”) in a py script?