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Issue in encode/decode in python 3 with non-ascii character

I am trying to use python3 unicode_escape to escape \n in my string, but the challenge is there are non-ascii characters present in the whole string, and if I use utf8 to encode and then decode the bytes using unicode_escape then the special character gets garbled. Is there any way to have the \n escaped with a new line without garbling the special character?
s = "hello\\nworld└--"
print(s.encode('utf8').decode('unicode_escape'))
Expected Result:
hello
world└--
Actual Result:
hello
worldâ--

As user wowcha observes, the unicode-escape codec assumes a latin-1 encoding, but your string contains a character that is not encodable as latin-1.
>>> s = "hello\\nworld└--"
>>> s.encode('latin-1')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'latin-1' codec can't encode character '\u2514' in position 12: ordinal not in range(256)
Encoding the string as utf-8 gets around the encoding problem, but results in mojibake when decoding from unicode-escape
The solution is to use the backslashreplace error handler when encoding. This will convert the problem character to an escape sequence that can be encoded as latin-1 and does not get mangled when decoded from unicode-escape.
>>> s.encode('latin-1', errors='backslashreplace')
b'hello\\nworld\\u2514--'
>>> s.encode('latin-1', errors='backslashreplace').decode('unicode-escape')
'hello\nworld└--'
>>> print(s.encode('latin-1', errors='backslashreplace').decode('unicode-escape'))
hello
world└--

Try removing the second escape backslash and decode using utf8:
>>> s = "hello\nworld└--"
>>> print(s.encode('utf8').decode('utf8'))
hello
world└--

I believe the problem you are having is that unicode_escape was deprecated in Python 3.3 and it seems to be assuming your code is 'latin-1' due to that being the original codec used within the unicode_excape function...
Looking at the python documentation for codecs we see that Encoding suitable as the contents of a Unicode literal in ASCII-encoded Python source code, except that quotes are not escaped. Decodes from Latin-1 source code. Beware that Python source code actually uses UTF-8 by default. which tells us that unicode_escape assumes that your text is ISO Latin-1.
So if we run your code with latin1 encoding we get this error:
s.encode('latin1')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'latin-1' codec can't encode character '\u2514' in position 12: ordinal not in range(256)
And the unicode character error is '\u2514' which when converted is '└' the simplest way to put it is the character cannot be used within a Latin-1 string hence why you get a different character.
I also think it's right to point out that within your string you have '\\n' and not just '\n' the extra backslash means this symbol is not carriage return but instead it is ignored the backward slash indicates to ignore the '\n'. Perhaps try not using the \\n...

Python Encoding error with some unicode characers

I am having some problems with encoding some unicode characters.
This is the code I am using:
test = raw_input("Test: ")
print test.encode("utf-8")
When I use now normal ASCII characters it works, same with some "strange" unicode characters like ☃.
But when I use characters like ß ä ö ü § it fails creating this error:
Traceback (most recent call last):
File "C:\###\Test.py", line 5, in <module>
print test.encode("utf-8")
UnicodeDecodeError: 'ascii' codec can't decode byte 0xdf in position 0: ordinal not in range(128)
Note that I am using a pc where German is the default language (so these characters are default characters).

raw_input() returns a byte string. You don't need to encode that byte string, it is already encoded.
What happens instead then is that Python will first decode to get a unicode value to encode; you asked Python to encode so it'll damn well try to get you something that can be encoded. It is the decoding that fails here. Implicit decoding uses ASCII, which is why you got a UnicodeDecodeError exception (note the Decode in the name) for that codec.
If you wanted to produce a unicode object you'd have to explicitly decode. Use the codec Python has detected for stdin:
import sys
test = raw_input("Test: ")
print test.decode(sys.stdin.encoding)
You don't need to do that here because you are printing, so writing right back to the same terminal which will use the same codec for input and output. Writing a byte string encoded with UTF-8 when you just received that byte string is then fine. Decoding to unicode is fine too, as printing will auto-encode to sys.stdout.encoding.

latin-1 vs unicode in python

I was reading this high rated post in SO on unicodes
Here is an `illustration given there :
$ python
>>> import sys
>>> print sys.stdout.encoding
UTF-8
>>> print '\xe9' # (1)
é
>>> print u'\xe9' # (2)
é
>>> print u'\xe9'.encode('latin-1') # (3)
é
>>>
and the explanation were given as
(1) python outputs binary string as is, terminal receives it and tries to match its value with latin-1 character map. In latin-1, 0xe9 or 233 yields the character "é" and so that's what the terminal displays.
My question is: why does the terminal match to the latin-1 character map when the encoding is 'UTF-8'?
Also when I tried
>>> print '\xe9'
?
>>> print u'\xe9'
é
I get different result for the first one than what is described above. why is this discrepancy and where does latin-1 come to play in this picture?

You are missing some important context; in that case the OP configured the terminal emulator (Gnome Terminal) to interpret output as Latin-1 but left the shell variables set to UTF-8. Python thus is told by the shell to use UTF-8 for Unicode output but the actual configuration of the terminal is to expect Latin-1 bytes.
The print output clearly shows the terminal is interpreting output using Latin-1, and is not using UTF-8.
When a terminal is set to UTF-8, the \xe9 byte is not valid (incomplete) UTF-8 and your terminal usually prints a question mark instead:
>>> import sys
>>> sys.stdout.encoding
'UTF-8'
>>> print '\xe9'
?
>>> print u'\xe9'
é
>>> print u'\xe9'.encode('utf8')
é
If you instruct Python to ignore such errors, it gives you the U+FFFD REPLACEMENT CHARACTER glyph � instead:
>>> '\xe9'.decode('utf8')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/mj/Development/venvs/stackoverflow-2.7/lib/python2.7/encodings/utf_8.py", line 16, in decode
return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0xe9 in position 0: unexpected end of data
>>> '\xe9'.decode('utf8', 'replace')
u'\ufffd'
>>> print '\xe9'.decode('utf8', 'replace')
�
That's because in UTF-8, \xe9 is the start byte of a 3-byte encoding, for the Unicode codepoints U+9000 through to U+9FFF, and if printed as just a single byte is invalid. This works:
>>> print '\xe9\x80\x80'
退
because that's the UTF-8 encoding of the U+9000 codepoint, a CJK Ideograph glyph.
If you want to understand the difference between encodings and Unicode, and how UTF-8 and other codecs work, I strongly recommend you read:
The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) by Joel Spolsky
The Python Unicode HOWTO
Pragmatic Unicode by Ned Batchelder

Strange behavior of string format in python 2.7

Working with svn logs in xml format i've accidentally got an error in my script.
Error message is:
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-9: ordinal not in range(128)
By debugging input data i have found what was wrong. Here is an example:
a=u'\u0440\u0435\u044c\u0434\u0437\u0444\u043a\u044b\u0443\u043a \u043c\u0443\u043a\u044b\u0448\u0449\u0442 \u0430\u0448\u0447'
>>> print a
реьдзфкыук мукышщт ашч
>>> print '{}'.format(a)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-9: ordinal not in range(128)
Can you please explain what is wrong with format?
Seems like it sees u before string bytes and try to decode it from UTF8.
However in Python 3 above example works without error.

You are mixing Unicode and byte string values. Use a unicode format:
print u'{}'.format(a)
Demo:
>>> a=u'\u0440\u0435\u044c\u0434\u0437\u0444\u043a\u044b\u0443\u043a \u043c\u0443\u043a\u044b\u0448\u0449\u0442 \u0430\u0448\u0447'
>>> print u'{}'.format(a)
реьдзфкыук мукышщт ашч
In Python 3, strings are unicode values by default; in Python 2, u"..." indicates a unicode value and regular strings ("...") are byte strings.
Mixing a byte strings and unicode value results in automatic encoding or decoding with the default codec (ASCII), and that's what happens here. The str.format() method has to encode the Unicode value to a byte string to interpolate.

Python: Sanitize a string for unicode? [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Python UnicodeDecodeError - Am I misunderstanding encode?
I have a string that I'm trying to make safe for the unicode() function:
>>> s = " foo “bar bar ” weasel"
>>> s.encode('utf-8', 'ignore')
Traceback (most recent call last):
File "<pyshell#8>", line 1, in <module>
s.encode('utf-8', 'ignore')
UnicodeDecodeError: 'ascii' codec can't decode byte 0x93 in position 5: ordinal not in range(128)
>>> unicode(s)
Traceback (most recent call last):
File "<pyshell#9>", line 1, in <module>
unicode(s)
UnicodeDecodeError: 'ascii' codec can't decode byte 0x93 in position 5: ordinal not in range(128)
I'm mostly flailing around here. What do I need to do to remove the unsafe characters from the string?
Somewhat related to this question, although I was unable to solve my problem from it.
This also fails:
>>> s
' foo \x93bar bar \x94 weasel'
>>> s.decode('utf-8')
Traceback (most recent call last):
File "<pyshell#13>", line 1, in <module>
s.decode('utf-8')
File "C:\Python25\254\lib\encodings\utf_8.py", line 16, in decode
return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0x93 in position 5: unexpected code byte

Good question. Encoding issues are tricky. Let's start with "I have a string." Strings in Python 2 aren't really "strings," they're byte arrays. So your string, where did it come from and what encoding is it in? Your example shows curly quotes in the literal, and I'm not even sure how you did that. I try to paste it into a Python interpreter, or type it on OS X with Option-[, and it doesn't come through.
Looking at your second example though, you have a character of hex 93. That can't be UTF-8, because in UTF-8, any byte higher than 127 is part of a multibyte sequence. So I'm guessing it's supposed to be Latin-1. The problem is, x93 isn't a character in the Latin-1 character set. There's this "invalid" range in Latin-1 from x7f to x9f that's considered illegal. However, Microsoft saw that unused range and decided to put "curly quotes" in there. In doing so they created this similar encoding called "windows-1252", which is like Latin-1 with stuff in that invalid range.
So, let's assume it is windows-1252. What now? String.decode converts bytes into Unicode, so that's the one you want. Your second example was on the right track, but it failed because the string wasn't UTF-8. Try:
>>> uni = 'foo \x93bar bar\x94 weasel'.decode("windows-1252")
u'foo \u201cbar bar\u201d weasel'
>>> print uni
foo “bar bar” weasel
>>> type(uni)
<type 'unicode'>
That's correct, because opening curly quote is Unicode U+201C. Now that you have Unicode, you can serialize it to bytes in any encoding you choose (if you need to pass it across the wire) or just keep it as Unicode if it's staying within Python. If you want to convert to UTF-8, use the oppose function, string.encode.
>>> uni.encode("utf-8")
'foo \xe2\x80\x9cbar bar \xe2\x80\x9d weasel'
Curly quotes take 3 bytes to encode in UTF-8. You could use UTF-16 and they'd only be two bytes. You can't encode as ASCII or Latin-1 though, because those don't have curly quotes.

EDIT. Looks like your string is encoded in such a way that “ (LEFT DOUBLE QUOTATION MARK) becomes \x93 and ” (RIGHT DOUBLE QUOTATION MARK) becomes \x94. There is a number of codepages with such a mapping, CP1250 is one of them, so you may use this:
s = s.decode('cp1250')
For all the codepages which map “ to \x93 see here (all of them also map ” to \x94, which can be verified here).