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How to convert a string to utf-8 in Python

I have a browser which sends utf-8 characters to my Python server, but when I retrieve it from the query string, the encoding that Python returns is ASCII. How can I convert the plain string to utf-8?

NOTE: The string passed from the web is already UTF-8 encoded, I just want to make Python to treat it as UTF-8 not ASCII.

I think a better title would be How to coerce a string to unicode without translation?
In 2018, python 3 if you get ascii decode error do "some_string".encode('utf-8').decode('utf-8')

M
Maxime

In Python 2

>>> plain_string = "Hi!"
>>> unicode_string = u"Hi!"
>>> type(plain_string), type(unicode_string)
(<type 'str'>, <type 'unicode'>)

^ This is the difference between a byte string (plain_string) and a unicode string.

>>> s = "Hello!"
>>> u = unicode(s, "utf-8")

^ Converting to unicode and specifying the encoding.

In Python 3

All strings are unicode. The unicode function does not exist anymore. See answer from @Noumenon


,I am getting the following error: UnicodeDecodeError: 'utf8' codec can't decode byte 0xb0 in position 2: invalid start byte This is my code: ret=[] for line in csvReader: cline=[] for elm in line: unicodestr = unicode(elm, 'utf-8') cline.append(unicodestr) ret.append(cline)
None of this applies in Python 3, all strings are unicode and unicode() doesn't exist.
How to you convert u back to a str format (convert u back to s)?
This code will only work as long as the text does not contain non-ascii characters; a simple accented character on the string will make it fail.
Hi, if you have "2340" in a string variable, and you want to print the unicode character U+2340 (⍀), is there any way to do that?
d
duhaime

If the methods above don't work, you can also tell Python to ignore portions of a string that it can't convert to utf-8:

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

Got AttributeError: 'str' object has no attribute 'decode'
@saran3h it sounds like you're using Python 3, in which case Python should handle encoding issues for you. Have you tried reading your document without specifying an encoding?
Python by default picks system encoding. In windows 10 it's cp1252 which is different from utf-8. I wasted few hours on it while using codecs.open() in py 3.8
T
Thavas Antonio

Might be a bit overkill, but when I work with ascii and unicode in same files, repeating decode can be a pain, this is what I use:

def make_unicode(inp):
    if type(inp) != unicode:
        inp =  inp.decode('utf-8')
    return inp

This no longer works, as written... the unicode type doesn't exist in python3
f
famousgarkin

Adding the following line to the top of your .py file:

# -*- coding: utf-8 -*-

allows you to encode strings directly in your script, like this:

utfstr = "ボールト"

It is not what OP asks. But avoid such string literals anyway. It creates Unicode string in Python 3 (good) but it is a bytestring in Python 2 (bad). Either add from __future__ import unicode_literals at the top or use u'' prefix. Don't use non-ascii characters in bytes literals. To get utf-8 bytes, you could utf8bytes = unicode_text.encode('utf-8') later if it is necessary.
@jfs how will from __future__ import unicode_literals help me to convert a string with non-ascii characters to utf-8?
@OrtalTurgeman I'm not answering the question. Look, it is a comment, not an answer. My comment addresses the issue with the code in the answer. It tries to create a bytestring with non-ascii characters on Python 2 (it is a SyntaxError on Python 3 — bytes literals forbid that).
c
codeape

If I understand you correctly, you have a utf-8 encoded byte-string in your code.

Converting a byte-string to a unicode string is known as decoding (unicode -> byte-string is encoding).

You do that by using the unicode function or the decode method. Either:

unicodestr = unicode(bytestr, encoding)
unicodestr = unicode(bytestr, "utf-8")

Or:

unicodestr = bytestr.decode(encoding)
unicodestr = bytestr.decode("utf-8")

W
Willem
city = 'Ribeir\xc3\xa3o Preto'
print city.decode('cp1252').encode('utf-8')

P
Pradeep R

In Python 3.6, they do not have a built-in unicode() method. Strings are already stored as unicode by default and no conversion is required. Example:

my_str = "\u221a25"
print(my_str)
>>> √25

J
Joe9008

Translate with ord() and unichar(). Every unicode char have a number asociated, something like an index. So Python have a few methods to translate between a char and his number. Downside is a ñ example. Hope it can help.

>>> C = 'ñ'
>>> U = C.decode('utf8')
>>> U
u'\xf1'
>>> ord(U)
241
>>> unichr(241)
u'\xf1'
>>> print unichr(241).encode('utf8')
ñ

s
shioko

First, str in Python is represented in Unicode.

Second, UTF-8 is an encoding standard to encode Unicode string to bytes. There are many encoding standards out there (e.g. UTF-16, ASCII, SHIFT-JIS, etc.).

When the client sends data to your server and they are using UTF-8, they are sending a bunch of bytes not str.

You received a str because the "library" or "framework" that you are using, has implicitly converted some random bytes to str.

Under the hood, there is just a bunch of bytes. You just need ask the "library" to give you the request content in bytes and you will handle the decoding yourself (if library can't give you then it is trying to do black magic then you shouldn't use it).

Decode UTF-8 encoded bytes to str: bs.decode('utf-8')

Encode str to UTF-8 bytes: s.encode('utf-8')


K
Kevin

you can also do this:

from unidecode import unidecode
unidecode(yourStringtoDecode)

What is unidecode? Is it this pypi.org/project/Unidecode? Please provide info if it's a 3rd-party package, and how to install/use it.
h
haccks

You can use python's standard library codecs module.

import codecs
codecs.decode(b'Decode me', 'utf-8')

D
David Buck

Yes, You can add

# -*- coding: utf-8 -*-

in your source code's first line.

You can read more details here https://www.python.org/dev/peps/pep-0263/