Changing Default Encoding of Python

Changing default encoding of Python?

Here is a simpler method (hack) that gives you back the setdefaultencoding() function that was deleted from sys:

import sys
# sys.setdefaultencoding() does not exist, here!
reload(sys)  # Reload does the trick!
sys.setdefaultencoding('UTF8')

(Note for Python 3.4+: reload() is in the importlib library.)

This is not a safe thing to do, though: this is obviously a hack, since sys.setdefaultencoding() is purposely removed from sys when Python starts. Reenabling it and changing the default encoding can break code that relies on ASCII being the default (this code can be third-party, which would generally make fixing it impossible or dangerous).

PS: This hack doesn't seem to work with Python 3.9 anymore.

python change character encoding to utf_8

Can you check encoding by following method:

>>> import sys
>>> sys.getdefaultencoding()
'utf-8'
>>> 

If encoding is ascii then set to utf-8

1. open following file(I am using Python 2.7):

   /usr/lib/python2.7/sitecustomize.py

2. then update following to utf-8

   sys.setdefaultencoding("utf-8")

[Edit 2]

Can you add following in tour code(at start) and then check:-

>>> try:
...     import apport_python_hook
... except ImportError:
...     pass
... else:
...     apport_python_hook.install()
... 
>>> import sys
>>> 
>>> sys.setdefaultencoding("utf-8")
>>> 
>>>

Persist UTF-8 as Default Encoding

Please take a look into site.py library - it is the place where sys.setdefaultencoding happens. You could, I think, modify or substitute this module in order to make it permanent on your machine. Here is some of it's source code, comments explains something:

def setencoding():
    """Set the string encoding used by the Unicode implementation.  The
    default is 'ascii', but if you're willing to experiment, you can
    change this."""

    encoding = "ascii" # Default value set by _PyUnicode_Init()
    if 0:
        # Enable to support locale aware default string encodings.
        import locale
        loc = locale.getdefaultlocale()
        if loc[1]:
            encoding = loc[1]
    if 0:
        # Enable to switch off string to Unicode coercion and implicit
        # Unicode to string conversion.
        encoding = "undefined"
    if encoding != "ascii":
        # On Non-Unicode builds this will raise an AttributeError...
        sys.setdefaultencoding(encoding) # Needs Python Unicode build !

Full source https://hg.python.org/cpython/file/2.7/Lib/site.py.

This is the place where they delete the sys.setdefaultencoding function, if you were wondering:

def main():

    ...

    # Remove sys.setdefaultencoding() so that users cannot change the
    # encoding after initialization.  The test for presence is needed when
    # this module is run as a script, because this code is executed twice.
    if hasattr(sys, "setdefaultencoding"):
        del sys.setdefaultencoding

Change python 3.7 default encoding from cp1252 to cp65001 aka UTF-8

This is resolved when putting the following at the top of your Python script. I am able to print all characters without error.

import sys
import io

sys.stdout = io.TextIOWrapper(sys.stdout.detach(), encoding = 'utf-8')
sys.stderr = io.TextIOWrapper(sys.stderr.detach(), encoding = 'utf-8')

How to change default character encoding for Python IDLE?

For 2.7, 3.5, the command line you show responds, for me, with cp437 - the IBM PC or DOS encoding. Output to the Windows console is limited to a subset of Basic Multilingual Plane (BMP) Unicode characters.

For 3.6, Python's handling of the Windows console was drastically improved to use utf-8 and potentially print any unicode character, depending on font availability.

For all current versions, IDLE also reports, for me, cp1252 (Latin 1). Since there is an attempt to get the system encoding, I don't know why the difference. But it hardly makes any difference as it is a dummy or fake value. To me, it is deceptive in that non-latin1 chars cannot be encoded with latin1, whereas all BMP chars can be printed in IDLE. So I have thought about a replacement.

When (unicode) strings are written to sys.stdout (usually with print), the string object is pickled to bytes in the user process, sent through a socket (implementation detail subject to change) to the IDLE process, and unpickled back to a string object. The effect is as if the string was encoded and decoded with one of the non-lossy utf codings. UTF-32 might be the closest to what pickling does.

The IDLE process calls tkinter text.insert(index, string), which asks tk to insert the string in the widget. But that only works for BMP characters. The net effect is as if the output encoding were ucs-2, though I believe tk uses a truncated utf-8 internally.

Similarly, any BMP character you enter in the shell or editor can be sent to the user process stdin after being displayed.

Anyway, changing pseudofile.encoding has no effect, which is why it was made read-only by this part of the patch for issue 9290

-        self.encoding = encoding
+        self._encoding = encoding
+
+    @property
+    def encoding(self):
+        return self._encoding

The initial underscore means that _encoding is a private (not hidden) implementation detail that should be ignored by users.

Python default string encoding

There are multiple parts of Python's functionality involved here: reading the source code and parsing the string literals, transcoding, and printing. Each has its own conventions.

Short answer:

• For the purpose of code parsing:
  
  • str (Py2) -- not applicable, raw bytes from the file are taken
  • unicode (Py2)/str (Py3) -- "source encoding", defaults are ascii (Py2) and utf-8 (Py3)
  • bytes (Py3) -- none, non-ASCII characters are prohibited in the literal
• For the purpose of transcoding:
  
  • both (Py2) -- sys.getdefaultencoding() (ascii almost always)
    
    • there are implicit conversions which often result in a UnicodeDecodeError/UnicodeEncodeError
  • both (Py3) -- none, must specify encoding explicitly when converting
• For the purpose of I/O:
  
  • unicode (Py2) -- <file>.encoding if set, otherwise sys.getdefaultencoding()
  • str (Py2) -- not applicable, raw bytes are written
  • str (Py3) -- <file>.encoding, always set and defaults to locale.getpreferredencoding()
  • bytes (Py3) -- none, printing produces its repr() instead

---

First of all, some terminology clarification so that you understand the rest correctly. Decoding is translation from bytes to characters (Unicode or otherwise), and encoding (as a process) is the reverse. See The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) – Joel on Software to get the distinction.

Now...

Reading the source and parsing string literals

At the start of a source file, you can specify the file's "source encoding" (its exact effect is described later). If not specified, the default is ascii for Python 2 and utf-8 for Python 3. A UTF-8 BOM has the same effect as a utf-8 encoding declaration.

Python 2

Python 2 reads the source as raw bytes. It only uses the "source encoding" to parse a Unicode literal when it sees one. (It's more complicated than that under the hood, but this is the net effect.)

> type t.py
# Encoding: cp1251
s = "абвгд"
us = u"абвгд"
print repr(s), repr(us)
> py -2 t.py
'\xe0\xe1\xe2\xe3\xe4' u'\u0430\u0431\u0432\u0433\u0434'

<change encoding declaration in the file to cp866, do not change the contents>
> py -2 t.py
'\xe0\xe1\xe2\xe3\xe4' u'\u0440\u0441\u0442\u0443\u0444'

<transcode the file to utf-8, update declaration or replace with BOM>
> py -2 t.py
'\xd0\xb0\xd0\xb1\xd0\xb2\xd0\xb3\xd0\xb4' u'\u0430\u0431\u0432\u0433\u0434'

So, regular strings will contain the exact bytes that are in the file. And Unicode strings will contain the result of decoding the file's bytes with the "source encoding".

If the decoding fails, you will get a SyntaxError. Same if there is a non-ASCII character in the file when there's no encoding specified. Finally, if unicode_literals future is used, any regular string literals (in that file only) are treated as Unicode literals when parsing, with all what that means.

Python 3

Python 3 decodes the entire source file with the "source encoding" into a sequence of Unicode characters. Any parsing is done after that. (In particular, this makes it possible to have Unicode in identifiers.) Since all string literals are now Unicode, no additional transcoding is needed. In byte literals, non-ASCII characters are prohibited (such bytes must be specified with escape sequences), evading the issue altogether.

Transcoding

As per the clarification at the start:

• str (Py2)/bytes (Py3) -- bytes => can only be decoded _{(directly, that is; details follow)}
• unicode (Py2)/str (Py3) -- characters => can only be encoded

Python 2

In both cases, if the encoding is not specified, sys.getdefaultencoding() is used. It is ascii _{(unless you uncomment a code chunk in site.py, or do some other hacks which are a recipe for disaster)}. So, for the purpose of transcoding, sys.getdefaultencoding() is the "string's default encoding".

Now, here's a caveat:

• a decode() and encode() -- with the default encoding -- is done implicitly when converting str<->unicode:

  • in string formatting (a third of UnicodeDecodeError/UnicodeEncodeError questions on Stack Overflow are about this)
  • when trying to encode() a str or decode() a unicode (the second third of the Stack Overflow questions)

Python 3

There's no "default encoding" at all: implicit conversion between str and bytes is now prohibited.

• bytes can only be decoded and str -- encoded, and the encoding argument is mandatory.
• converting bytes->str (incl. implicitly) produces its repr() instead (which is only useful for debug printing), evading the encoding issue entirely
• converting str->bytes is prohibited

Printing

This matter is unrelated to a variable's value but related to what you would see on the screen when it's printed -- and whether you will get a UnicodeEncodeError when printing.

Python 2

• A unicode is encoded with <file>.encoding if set; otherwise, it's implicitly converted to str as per the above. (The final third of the UnicodeEncodeError SO questions fall into here.)
  
  • For standard streams, the stream's encoding is guessed at startup from various environment-specific sources, and can be overridden with the PYTHONIOENCODING environment variable.
• str's bytes are sent to the OS stream as-is. What specific glyphs you will see on the screen depends on your terminal's encoding settings (if it's something like UTF-8, you may see nothing at all if you print a byte sequence that is invalid UTF-8).

Python 3

The changes are:

• Now files opened with text vs. binary mode natively accept str or bytes, correspondingly, and outright refuse to process the wrong type. Text-mode files always have an encoding set, locale.getpreferredencoding(False) being the default.
• print for text streams still implicitly converts everything to str, which in the case of bytes prints its repr() as per the above, evading the encoding issue altogether

Is there a way to change the default encoding for all run configurations within Pydev?

You can change the default encoding at window > preferences > general > workspace > text file encoding (set it to other > us-ascii).

Why i can't change my python default encoding?

You need to read following:

1. Why should we NOT use sys.setdefaultencoding("utf-8") in a py script?
2. How to print UTF-8 encoded text to the console in Python < 3?

I recommend using # -*- coding: utf-8 -*- to top of your .py file.

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