Develop Reference

FPDF encoding error when reading a UTF8 txt file in Python [duplicate]

I'm having some brain failure in understanding reading and writing text to a file (Python 2.4).
# The string, which has an a-acute in it.
ss = u'Capit\xe1n'
ss8 = ss.encode('utf8')
repr(ss), repr(ss8)
("u'Capit\xe1n'", "'Capit\xc3\xa1n'")
print ss, ss8
print >> open('f1','w'), ss8
>>> file('f1').read()
'Capit\xc3\xa1n\n'
So I type in Capit\xc3\xa1n into my favorite editor, in file f2.
Then:
>>> open('f1').read()
'Capit\xc3\xa1n\n'
>>> open('f2').read()
'Capit\\xc3\\xa1n\n'
>>> open('f1').read().decode('utf8')
u'Capit\xe1n\n'
>>> open('f2').read().decode('utf8')
u'Capit\\xc3\\xa1n\n'
What am I not understanding here? Clearly there is some vital bit of magic (or good sense) that I'm missing. What does one type into text files to get proper conversions?
What I'm truly failing to grok here, is what the point of the UTF-8 representation is, if you can't actually get Python to recognize it, when it comes from outside. Maybe I should just JSON dump the string, and use that instead, since that has an asciiable representation! More to the point, is there an ASCII representation of this Unicode object that Python will recognize and decode, when coming in from a file? If so, how do I get it?
>>> print simplejson.dumps(ss)
'"Capit\u00e1n"'
>>> print >> file('f3','w'), simplejson.dumps(ss)
>>> simplejson.load(open('f3'))
u'Capit\xe1n'

Rather than mess with .encode and .decode, specify the encoding when opening the file. The io module, added in Python 2.6, provides an io.open function, which allows specifying the file's encoding.
Supposing the file is encoded in UTF-8, we can use:
>>> import io
>>> f = io.open("test", mode="r", encoding="utf-8")
Then f.read returns a decoded Unicode object:
>>> f.read()
u'Capit\xe1l\n\n'
In 3.x, the io.open function is an alias for the built-in open function, which supports the encoding argument (it does not in 2.x).
We can also use open from the codecs standard library module:
>>> import codecs
>>> f = codecs.open("test", "r", "utf-8")
>>> f.read()
u'Capit\xe1l\n\n'
Note, however, that this can cause problems when mixing read() and readline().

In the notation u'Capit\xe1n\n' (should be just 'Capit\xe1n\n' in 3.x, and must be in 3.0 and 3.1), the \xe1 represents just one character. \x is an escape sequence, indicating that e1 is in hexadecimal.
Writing Capit\xc3\xa1n into the file in a text editor means that it actually contains \xc3\xa1. Those are 8 bytes and the code reads them all. We can see this by displaying the result:
# Python 3.x - reading the file as bytes rather than text,
# to ensure we see the raw data
>>> open('f2', 'rb').read()
b'Capit\\xc3\\xa1n\n'
# Python 2.x
>>> open('f2').read()
'Capit\\xc3\\xa1n\n'
Instead, just input characters like á in the editor, which should then handle the conversion to UTF-8 and save it.
In 2.x, a string that actually contains these backslash-escape sequences can be decoded using the string_escape codec:
# Python 2.x
>>> print 'Capit\\xc3\\xa1n\n'.decode('string_escape')
Capitán
The result is a str that is encoded in UTF-8 where the accented character is represented by the two bytes that were written \\xc3\\xa1 in the original string. To get a unicode result, decode again with UTF-8.
In 3.x, the string_escape codec is replaced with unicode_escape, and it is strictly enforced that we can only encode from a str to bytes, and decode from bytes to str. unicode_escape needs to start with a bytes in order to process the escape sequences (the other way around, it adds them); and then it will treat the resulting \xc3 and \xa1 as character escapes rather than byte escapes. As a result, we have to do a bit more work:
# Python 3.x
>>> 'Capit\\xc3\\xa1n\n'.encode('ascii').decode('unicode_escape').encode('latin-1').decode('utf-8')
'Capitán\n'

Now all you need in Python3 is open(Filename, 'r', encoding='utf-8')
[Edit on 2016-02-10 for requested clarification]
Python3 added the encoding parameter to its open function. The following information about the open function is gathered from here: https://docs.python.org/3/library/functions.html#open
open(file, mode='r', buffering=-1,
encoding=None, errors=None, newline=None,
closefd=True, opener=None)
Encoding is the name of the encoding used to decode or encode the
file. This should only be used in text mode. The default encoding is
platform dependent (whatever locale.getpreferredencoding()
returns), but any text encoding supported by Python can be used.
See the codecs module for the list of supported encodings.
So by adding encoding='utf-8' as a parameter to the open function, the file reading and writing is all done as utf8 (which is also now the default encoding of everything done in Python.)

So, I've found a solution for what I'm looking for, which is:
print open('f2').read().decode('string-escape').decode("utf-8")
There are some unusual codecs that are useful here. This particular reading allows one to take UTF-8 representations from within Python, copy them into an ASCII file, and have them be read in to Unicode. Under the "string-escape" decode, the slashes won't be doubled.
This allows for the sort of round trip that I was imagining.

This works for reading a file with UTF-8 encoding in Python 3.2:
import codecs
f = codecs.open('file_name.txt', 'r', 'UTF-8')
for line in f:
print(line)

# -*- encoding: utf-8 -*-
# converting a unknown formatting file in utf-8
import codecs
import commands
file_location = "jumper.sub"
file_encoding = commands.getoutput('file -b --mime-encoding %s' % file_location)
file_stream = codecs.open(file_location, 'r', file_encoding)
file_output = codecs.open(file_location+"b", 'w', 'utf-8')
for l in file_stream:
file_output.write(l)
file_stream.close()
file_output.close()

Aside from codecs.open(), io.open() can be used in both 2.x and 3.x to read and write text files. Example:
import io
text = u'á'
encoding = 'utf8'
with io.open('data.txt', 'w', encoding=encoding, newline='\n') as fout:
fout.write(text)
with io.open('data.txt', 'r', encoding=encoding, newline='\n') as fin:
text2 = fin.read()
assert text == text2

To read in an Unicode string and then send to HTML, I did this:
fileline.decode("utf-8").encode('ascii', 'xmlcharrefreplace')
Useful for python powered http servers.

Well, your favorite text editor does not realize that \xc3\xa1 are supposed to be character literals, but it interprets them as text. That's why you get the double backslashes in the last line -- it's now a real backslash + xc3, etc. in your file.
If you want to read and write encoded files in Python, best use the codecs module.
Pasting text between the terminal and applications is difficult, because you don't know which program will interpret your text using which encoding. You could try the following:
>>> s = file("f1").read()
>>> print unicode(s, "Latin-1")
Capitán
Then paste this string into your editor and make sure that it stores it using Latin-1. Under the assumption that the clipboard does not garble the string, the round trip should work.

You have stumbled over the general problem with encodings: How can I tell in which encoding a file is?
Answer: You can't unless the file format provides for this. XML, for example, begins with:
<?xml encoding="utf-8"?>
This header was carefully chosen so that it can be read no matter the encoding. In your case, there is no such hint, hence neither your editor nor Python has any idea what is going on. Therefore, you must use the codecs module and use codecs.open(path,mode,encoding) which provides the missing bit in Python.
As for your editor, you must check if it offers some way to set the encoding of a file.
The point of UTF-8 is to be able to encode 21-bit characters (Unicode) as an 8-bit data stream (because that's the only thing all computers in the world can handle). But since most OSs predate the Unicode era, they don't have suitable tools to attach the encoding information to files on the hard disk.
The next issue is the representation in Python. This is explained perfectly in the comment by heikogerlach. You must understand that your console can only display ASCII. In order to display Unicode or anything >= charcode 128, it must use some means of escaping. In your editor, you must not type the escaped display string but what the string means (in this case, you must enter the umlaut and save the file).
That said, you can use the Python function eval() to turn an escaped string into a string:
>>> x = eval("'Capit\\xc3\\xa1n\\n'")
>>> x
'Capit\xc3\xa1n\n'
>>> x[5]
'\xc3'
>>> len(x[5])
1
As you can see, the string "\xc3" has been turned into a single character. This is now an 8-bit string, UTF-8 encoded. To get Unicode:
>>> x.decode('utf-8')
u'Capit\xe1n\n'
Gregg Lind asked: I think there are some pieces missing here: the file f2 contains: hex:
0000000: 4361 7069 745c 7863 335c 7861 316e Capit\xc3\xa1n
codecs.open('f2','rb', 'utf-8'), for example, reads them all in a separate chars (expected) Is there any way to write to a file in ASCII that would work?
Answer: That depends on what you mean. ASCII can't represent characters > 127. So you need some way to say "the next few characters mean something special" which is what the sequence "\x" does. It says: The next two characters are the code of a single character. "\u" does the same using four characters to encode Unicode up to 0xFFFF (65535).
So you can't directly write Unicode to ASCII (because ASCII simply doesn't contain the same characters). You can write it as string escapes (as in f2); in this case, the file can be represented as ASCII. Or you can write it as UTF-8, in which case, you need an 8-bit safe stream.
Your solution using decode('string-escape') does work, but you must be aware how much memory you use: Three times the amount of using codecs.open().
Remember that a file is just a sequence of bytes with 8 bits. Neither the bits nor the bytes have a meaning. It's you who says "65 means 'A'". Since \xc3\xa1 should become "à" but the computer has no means to know, you must tell it by specifying the encoding which was used when writing the file.

The \x.. sequence is something that's specific to Python. It's not a universal byte escape sequence.
How you actually enter in UTF-8-encoded non-ASCII depends on your OS and/or your editor. Here's how you do it in Windows. For OS X to enter a with an acute accent you can just hit option + E, then A, and almost all text editors in OS X support UTF-8.

You can also improve the original open() function to work with Unicode files by replacing it in place, using the partial function. The beauty of this solution is you don't need to change any old code. It's transparent.
import codecs
import functools
open = functools.partial(codecs.open, encoding='utf-8')

I was trying to parse iCal using Python 2.7.9:
from icalendar import Calendar
But I was getting:
Traceback (most recent call last):
File "ical.py", line 92, in parse
print "{}".format(e[attr])
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe1' in position 7: ordinal not in range(128)
and it was fixed with just:
print "{}".format(e[attr].encode("utf-8"))
(Now it can print liké á böss.)

I found the most simple approach by changing the default encoding of the whole script to be 'UTF-8':
import sys
reload(sys)
sys.setdefaultencoding('utf8')
any open, print or other statement will just use utf8.
Works at least for Python 2.7.9.
Thx goes to https://markhneedham.com/blog/2015/05/21/python-unicodeencodeerror-ascii-codec-cant-encode-character-uxfc-in-position-11-ordinal-not-in-range128/ (look at the end).

python codecs can't encode to cp1252...but notepad++ can?

I have a very simple piece of code that's converting a csv....also do note i reference notepad++ a few times but my standard IDE is vs-code.
with codecs.open(filePath, "r", encoding = "UTF-8") as sourcefile:
lines = sourcefile.read()
with codecs.open(filePath, 'w', encoding = 'cp1252') as targetfile:
targetfile.write(lines)
Now the job I'm doing requires a specific file be encoded to windows-1252 and from what i understand cp1252=windows-1252. Now this conversion works fine when i do it using the UI features in notepad++, but when i try using python codecs to encode this file it fails;
UnicodeEncodeError: 'charmap' codec can't encode character '\ufffd' in position 561488: character maps to <undefined>
When i saw this failure i was confused, so i double checked the output from when i manually convert the file using notepad++, and the converted file is encoded in windows-1252.....so what gives? Why can a UI feature in notepad++ able to do the job when but codecs seems not not be able to? Does notepad++ just ignore errors?

Looks like your input text has the character "�" (the actual placeholder "replacement character" character, not some other undefined character), which cannot be mapped to cp1252 (because it doesn't have the concept).
Depending on what you need, you can:
Filter it out (or replace it, or otherwise handle it) in Python before writing out lines to the output file.
Pass errors=... to the second codecs.open, choosing one of the other error-handling modes; the default is 'strict', you can also use 'ignore', 'replace', 'xmlcharrefreplace', 'backslashreplace' or 'namereplace'.
Check the input file and see why it's got the "�" character; is it corrupted?

Probably Python is simply more explicit in its error handling. If Notepad++ managed to represent every character correctly in CP-1252 then there is a bug in the Python codec where it should not fail where it currently does; but I'm guessing Notepad++ is silently replacing some characters with some other characters, and falsely claiming success.
Maybe try converting the result back to UTF-8 and compare the files byte by byte if the data is not easy to inspect manually.
Uncode U+FFFD is a reserved character which serves as a placeholder for a character which cannot be represented in Unicode; often, it's an indication of a conversion problem previously, when presumably this data was imperfectly input or converted at an earlier point in time.
(And yes, Windows-1252 is another name for Windows code page 1252.)

Why notepad++ "succeeds"
Notepad++ does not offer you to convert your file to cp1252, but to reinterpret it using this encoding. What lead to your confusion is that they are actually using the wrong term for this. This is the encoding menu in the program:
When "Encode with cp1252" is selected, Notepad decodes the file using cp1252 and shows you the result. If you save the character '\ufffd' to a file using utf8:
with open('f.txt', 'w', encoding='utf8') as f:
f.write('\ufffd')`
and use "Encode with cp1252" you'd see three characters:
That means that Notepad++ does not read the character in utf8 and then writes it in cp1252, because then you'd see exactly one character. You could achieve similar results to Notepad++ by reading the file using cp1252:
with open('f.txt', 'r', encoding='cp1252') as f:
print(f.read()) # Prints �
Notepad++ lets you actually convert to only five encodings, as you can see in the screenshot above.
What should you do
This character does not exist in the cp1252 encoding, which means you can't convert this file without losing information. Common solutions are to skip such characters or replace them with other similar characters that exist in your encoding (see encoding error handlers)

You are dealing with the "utf-8-sig" encoding -- please specify this one as the encoding argument instead of "utf-8".
There is information on it in the docs (search the page for "utf-8-sig").
To increase the reliability with which a UTF-8 encoding can be detected, Microsoft invented a variant of UTF-8 (that Python 2.5 calls "utf-8-sig") for its Notepad program: Before any of the Unicode characters is written to the file, a UTF-8 encoded BOM (which looks like this as a byte sequence: 0xef, 0xbb, 0xbf) is written. [...]

hi-ascii characters python string

I am always perplexed with the whole hi-ascii handling in python 2.x. I am currently facing an issue in which I have a string with hiascii characters in it. I have a few questions related to it.
How can a string store hiascii characters in it (not a unicode string, but a normal str in python 2.x), which I thought can handle only ascii chars. Does python internally convert the hiascii to something else ?
I have a cli which I spawn as a subprocess from my python code, when I pass this string to the cli, it works fine. While, if I encode this string to utf-8, the cli fails( this string is a password, so it fails saying the password is invalid).
For the second point, I actually did a bit of research and found the following:
1) In windows(sucks), the command line args are encoded in mbcs (sys.getfilesystemencoding). The question I still don't get is, if I read the same string using raw_input, it is encoded in Windows console encoding(on EN windows, it was cp437).
I have a different question that am confused about now regarding Windows encoding. Is the windows sys.stdin.encoding different from Windows console encoding ?
If yes, is there a pythonic way to figure out what my windows console encoding is. I needed this because when I read input using raw_input, its encoded in Windows console encoding, and I want to convert it to say, utf-8. Note: I have already set my sys.stdin.encoding to utf-8, but it doesnt seem to make any effect in the read input.

To answer your first question, Python 2.x byte strings contain the source-encoded bytes of the characters, meaning the exact bytes used to store the string on disk in the source file. For example, here is a Python 2.x program where the source is saved in Windows-1252 encoding (Notepad's default on US Windows):
#!python2
#coding:windows-1252
s = 'æüÿ€éêè'
u = u'æüÿ€éêè'
print repr(s)
print repr(u)
Output:
'\xe6\xfc\xff\x80\xe9\xea\xe8'
u'\xe6\xfc\xff\u20ac\xe9\xea\xe8'
The byte string contains the bytes that represent the characters in Windows-1252.
The Python decodes that same sequence of using the declared source encoding (!#coding:Windows-1252) into Unicode codepoints. Since Windows-1252 is very close to iso-8859-1, and iso-8859-1 is a 1:1 mapping to the first 0-255 Unicode codepoints, the code points are almost the same, except for the Euro character.
But save the source in a different encoding, and you'll get those bytes instead for the byte string:
#!python2
#coding:utf8
s = 'æüÿ€éêè'
u = u'æüÿ€éêè'
print repr(s)
print repr(u)
Output:
'\xc3\xa6\xc3\xbc\xc3\xbf\xe2\x82\xac\xc3\xa9\xc3\xaa\xc3\xa8'
u'\xe6\xfc\xff\u20ac\xe9\xea\xe8'
So, Python 2.X just gives you the source code bytes directly, without decoding them to Unicode codepoints, like a Unicode string would do.
Python 3.X notes that this is confusing, and just forbids non-ASCII characters in byte strings:
#!python3
#coding:utf8
s = b'æüÿ€éêè'
u = 'æüÿ€éêè'
print(repr(s))
print(repr(u))
Output:
File "C:\test.py", line 3
s = b'æüÿ\u20acéêè'
^
SyntaxError: bytes can only contain ASCII literal characters.
To answer your second question, please edit your question to show an example that demonstrates the problem.

Is the windows sys.stdin.encoding different from Windows console encoding?
Yes. There are two locale-specific codepages:
the ANSI code page, aka mbcs, used for strings in Win32 ...A APIs and hence for C runtime operations like reading the command line;
the IO code page, used for stdin/stdout/stderr streams.
These do not have to be the same encoding, and typically they aren't. In my locale (UK), the ANSI code page is 1252 and the IO code page defaults to 850. You can change the console code page using the chcp command, so you can make the two encodings match using eg chcp 1252 before running the Python command.
(You also have to be using a TrueType font in the console for chcp to make any difference.)
is there a pythonic way to figure out what my windows console encoding is.
Python reads it at startup using the Win32 API GetConsoleOutputCP and—unless overridden by PYTHONIOENCODING—writes that to the property sys.stdout.encoding. (Similarly GetConsoleCP for stdin though they will generally be the same code page.)
If you need to read this directly, regardless of whether PYTHONIOENCODING is set, you might have to use ctypes to call GetConsoleOutputCP directly.
Note: I have already set my sys.stdin.encoding to utf-8, but it doesnt seem to make any effect in the read input.
(How have you done that? It's a read-only property.)
Although you can certainly treat input and output as UTF-8 at your end, the Windows console won't supply or display content in that encoding. Most other tools you call via the command line will also be treating their input as encoded in the IO code page, so would misinterpret any UTF-8 sent to them.
You can affect what code page the console side uses by calling the Win32 SetConsoleCP/SetConsoleOutputCP APIs with ctypes (equivalent of the chcp command and also requires TTF console font). In principle you should be able to set code page 65001 and get something that is nearly UTF-8. Unfortunately long-standing console bugs usually make this approach infeasible.
windows(sucks)
yes.

error :: UnicodeDecodeError

I am getting
UnicodeDecodeError: 'ascii' codec can't decode byte 0xb0 in position 104: ordinal not in range(128)
I am using intgereproparty, stringproparty, datetimeproparty

That's because 0xb0 (decimal 176) is not a valid character code in ASCII (which defines only values between 0 and 127).
Check where you got that string from and use the proper encoding.
If you need further help, post the code.

You are trying to put Unicode data (probably text with accents) into an ASCII string.
You can use Python's codecs module to open a text file with UTF-8 encoding and write the Unicode data to it.
The .encode method may also help (u"õ".encode('utf-8') for example)

Python defaults to ASCII encoding - if you are dealing with chars outside of the ASCII range, you need to specify that in your code.
One way to do this is setting the defining the encoding at the top of your code.
This snippet sets the encoding at the top of the file to encoding to Latin-1 (which includes 0xb0):
#!/usr/bin/python
# -*- coding: latin-1 -*-
import os, sys
...
See PEP for more info on encoding.

When I write my foreign language "flashcard" programs, I always use python 3.x as its native encoding is utf-8. You're encoding problems will generally be far less frequent.
If you're working on a program that many people will share, however, you may want to consider using encode and decode with python 2.x, but only when storing and retrieving data elements in persistent storage. encode your non-ASCII characters, silently manipulate hexadecimal representations of those unicode strings in memory, and save them as hexadecimal. Finally, use decode when fetching unicode strings from persistant storage, but for end user display only. This will eliminate the need to constantly encode and decode your strings in your program.
#jcoon also has a pretty standard response to this problem.

python, and unicode stderr

I used an anonymous pipe to capture all stdout,and stderr then print into a richedit, it's ok when i use wsprintf ,but the python using multibyte char that really annoy me. how can I convert all these output to unicode?
UPDATE 2010-01-03:
Thank you for the reply, but it seems the str.encode() only worked with print xxx stuff, if there is an error during the py_runxxx(), my redirected stderr will capture the error message in multibyte string, so is there a way can make python output it's message in unicode way? And there seems to be an available solution in this post.
I'll try it later.

First, please remember that on Windows console may not fully support Unicode.
The example below does make python output to stderr and stdout using UTF-8. If you want you could change it to other encodings.
#!/usr/bin/python
# -*- coding: UTF-8 -*-
import codecs, sys
reload(sys)
sys.setdefaultencoding('utf-8')
print sys.getdefaultencoding()
sys.stdout = codecs.getwriter('utf8')(sys.stdout)
sys.stderr = codecs.getwriter('utf8')(sys.stderr)
print "This is an Е乂αmp١ȅ testing Unicode support using Arabic, Latin, Cyrillic, Greek, Hebrew and CJK code points."

You can work with Unicode in python either by marking strings as Unicode (ie: u'Hello World') or by using the encode() method that all strings have.
Eg. assuming you have a Unicode string, aStringVariable:
aStringVariable.encode('utf-8')
will convert it to UTF-8. 'utf-16' will give you UTF-16 and 'ascii' will convert it to a plain old ASCII string.
For more information, see:
Tutorial - Unicode Strings
Python String Methods

wsprintf?
This seems to be a "C/C++" question rather than a Python question.
The Python interpreter always writes bytestrings to stdout/stderr, rather than unicode (or "wide") strings. It means Python first encodes all unicode data using the current encoding (likely sys.getdefaultencoding()).
If you want to get at stdout/stderr as unicode data, you must decode it by yourself using the right encoding.
Your favourite C/C++ library certainly has what it takes to do that.