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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).
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. [...]
Say I have a function:
def NewFunction():
return '£'
I want to print some stuff with a pound sign in front of it and it prints an error when I try to run this program, this error message is displayed:
SyntaxError: Non-ASCII character '\xa3' in file 'blah' but no encoding declared;
see http://www.python.org/peps/pep-0263.html for details
Can anyone inform me how I can include a pound sign in my return function? I'm basically using it in a class and it's within the '__str__' part that the pound sign is included.
I'd recommend reading that PEP the error gives you. The problem is that your code is trying to use the ASCII encoding, but the pound symbol is not an ASCII character. Try using UTF-8 encoding. You can start by putting # -*- coding: utf-8 -*- at the top of your .py file. To get more advanced, you can also define encodings on a string by string basis in your code. However, if you are trying to put the pound sign literal in to your code, you'll need an encoding that supports it for the entire file.
Adding the following two lines at the top of my .py script worked for me (first line was necessary):
#!/usr/bin/env python
# -*- coding: utf-8 -*-
First add the # -*- coding: utf-8 -*- line to the beginning of the file and then use u'foo' for all your non-ASCII unicode data:
def NewFunction():
return u'£'
or use the magic available since Python 2.6 to make it automatic:
from __future__ import unicode_literals
The error message tells you exactly what's wrong. The Python interpreter needs to know the encoding of the non-ASCII character.
If you want to return U+00A3 then you can say
return u'\u00a3'
which represents this character in pure ASCII by way of a Unicode escape sequence. If you want to return a byte string containing the literal byte 0xA3, that's
return b'\xa3'
(where in Python 2 the b is implicit; but explicit is better than implicit).
The linked PEP in the error message instructs you exactly how to tell Python "this file is not pure ASCII; here's the encoding I'm using". If the encoding is UTF-8, that would be
# coding=utf-8
or the Emacs-compatible
# -*- encoding: utf-8 -*-
If you don't know which encoding your editor uses to save this file, examine it with something like a hex editor and some googling. The Stack Overflow character-encoding tag has a tag info page with more information and some troubleshooting tips.
In so many words, outside of the 7-bit ASCII range (0x00-0x7F), Python can't and mustn't guess what string a sequence of bytes represents. https://tripleee.github.io/8bit#a3 shows 21 possible interpretations for the byte 0xA3 and that's only from the legacy 8-bit encodings; but it could also very well be the first byte of a multi-byte encoding. But in fact, I would guess you are actually using Latin-1, so you should have
# coding: latin-1
as the first or second line of your source file. Anyway, without knowledge of which character the byte is supposed to represent, a human would not be able to guess this, either.
A caveat: coding: latin-1 will definitely remove the error message (because there are no byte sequences which are not technically permitted in this encoding), but might produce completely the wrong result when the code is interpreted if the actual encoding is something else. You really have to know the encoding of the file with complete certainty when you declare the encoding.
Adding the following two lines in the script solved the issue for me.
# !/usr/bin/python
# coding=utf-8
Hope it helps !
You're probably trying to run Python 3 file with Python 2 interpreter. Currently (as of 2019), python command defaults to Python 2 when both versions are installed, on Windows and most Linux distributions.
But in case you're indeed working on a Python 2 script, a not yet mentioned on this page solution is to resave the file in UTF-8+BOM encoding, that will add three special bytes to the start of the file, they will explicitly inform the Python interpreter (and your text editor) about the file encoding.
I'm trying to execute a simple utility I wrote for Linux, which I thought it would be executed without problem on Windows. Wrong.
The script parses a simple file using the "re" module for regex. The problem is that the expression fails every time because Windows doesn't treat well the text file, which is UTF-8, because it contains things like áéíóú or ñ (it's in Spanish).
I've found a lot of stuff about printing text in Unicode format, but have found nothing about reading an Unicode line from a text file or using regex with Unicode on Windows. Thought you might shed some light on the subject.
open() uses locale.getpreferredencoding(False) encoding to decode a file. It is likely to be utf-8 on POSIX systems and it is something else on Windows e.g., cp1252.
If you know the text in the file is stored using utf-8 character encoding then pass it explicitly:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import io
import re
with io.open("filename.txt", encoding='utf-8') as file:
for line in file:
if re.search(u"(?u)unicode\s+pattern…", line):
# found..
Probably I completely don't understand it, so can you take a look at code examples and tell my what should I do, to be sure it will work?
I tried it in Eclipse with Pydev. I use python 2.6.6 (becuase of some library that not support python 2.7).
First, without using codecs module
# -*- coding: utf-8 -*-
file1 = open("samoloty1.txt", "w")
file2 = open("samoloty2.txt", "w")
file3 = open("samoloty3.txt", "w")
file4 = open("samoloty4.txt", "w")
file5 = open("samoloty5.txt", "w")
file6 = open("samoloty6.txt", "w")
# I know that this is weird, but it shows that whatever i do, it not ruin anything...
print u"ą✈✈"
file1.write(u"ą✈✈")
print "ą✈✈"
file2.write("ą✈✈")
print "ą✈✈".decode("utf-8")
file3.write("ą✈✈".decode("utf-8"))
print "ą✈✈".encode("utf-8")
file4.write("ą✈✈".encode("utf-8"))
print u"ą✈✈".decode("utf-8")
file5.write(u"ą✈✈".decode("utf-8"))
print u"ą✈✈".encode("utf-8")
file6.write(u"ą✈✈".encode("utf-8"))
file1.close()
file2.close()
file3.close()
file4.close()
file5.close()
file6.close()
file1 = open("samoloty1.txt", "r")
file2 = open("samoloty2.txt", "r")
file3 = open("samoloty3.txt", "r")
file4 = open("samoloty4.txt", "r")
file5 = open("samoloty5.txt", "r")
file6 = open("samoloty6.txt", "r")
print file1.read()
print file2.read()
print file3.read()
print file4.read()
print file5.read()
print file6.read()
Every each of those prints works correctly and I don't get any funny characters.
Also i tried this: i delete all files made in the previous test and change only those lines:
file1 = open("samoloty1.txt", "w")
to those:
file1 = codecs.open("samoloty1.txt", "w", encoding='utf-8')
and again everything works...
Can anyone make some examples what works, and what not?
Should this be separate question?
I am downloading web pages, through this:
content = urllib.urlopen(some_url).read()
ucontent = unicode(content, encoding) # i get encoding from headers
Is this correct and enough? What should I do next with it to store it in utf-8 file? (I ask it because whatever I did before, it just works...)
** UPDATE **
Probably everything works ok because PyDev (or just Eclipse) has terminal encoded in UTF-8. So for tests i used cmd from Windows 7 and i get some errors. Now everything was crashing as expected. :D Here i am showing what i changed to get it working again (and all of those changes are reasonable for me and they agree with what i learn in answers and in docs in Python documentations).
print u"ą✈✈".encode("utf-8") # added encode
file1.write(u"ą✈✈".encode("utf-8")) # added encode
print "ą✈✈"
file2.write("ą✈✈")
print "ą✈✈" # removed .decode("utf-8")
file3.write("ą✈✈") # removed .decode("utf-8"))
print "ą✈✈" # removed .encode("utf-8")
file4.write("ą✈✈") # removed .encode("utf-8"))
print u"ą✈✈".encode("utf-8") # changed from .decode("utf-8")
file5.write(u"ą✈✈".encode("utf-8")) # changed from .decode("utf-8")
print u"ą✈✈".encode("utf-8")
file6.write(u"ą✈✈".encode("utf-8"))
And like someone said, when i use codecs, i not need to use encode() everytime before writing to file. :)
Question is, which answer should be marked as correct?
You are just lucky that the encoding of your console is utf-8 by default.
If you pass a unicode object to the write method method of a file object (sys.stdout) the object is implicitly decoded with its encoding attribute.
Thouse who work in Windows are not so lucky: How to workaround Python "WindowsError messages are not properly encoded" problem?
All those write exercises in the code snippet actually boil down to two situations:
when you write string to the file
when you try to write unicode string to the file
Lets call string as s and unicode string as u.
Then fileN.write(s) makes sense, and fileN.write(u) doesn't. I don't know about your setup (maybe you have made some changes to site's python), but the following expectedly breaks here:
# -*- coding: utf-8 -*-
ff = open("ff.txt", "w")
ff.write(u"ą✈✈")
ff.close()
with:
Traceback (most recent call last):
File "ex.py", line 5, in <module>
ff.write(u"ą✈✈")
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-2: ordinal not in range(128)
It means, that unicode string should be changed to string before writing to file. And your file6 example shows how to do it:
u"ą✈✈".encode("utf-8")
The magic string -*- coding: utf-8 -*- is the one which enables you to write unicode string literals in a WYSIWYG way: u"ą✈✈", it doesn't help you to determine your encoding in any other situation.
Thus, do not give .write() method in Python2.6 any unicode string. The good practice is to work with unicode strings in your code but convert from/to concrete encoding at the input/output borders.
The codecs example is good, as well as urllib.
What you are doing is correct. See this Python unicode howto for more info.
The general principles are:
When binary data comes in to your application (e.g., open(), urllib.urlopen()), use the decode() method to get a unicode string.
If the byte string is invalid for the supplied encoding, you may get UnicodeDecodeError. In this case do one of the following:
Use the second argument to decode to either replace or ignore bad characters
try harder to find out what the real encoding is
fix the input if it really is mangled.
For files, you can use the codecs.open wrappers to do this transparently for you.
Network data you must generally decode by hand, but sometimes the payload declares its own encoding (e.g., html, XML), and sometimes it doesn't match the header!
For database data, usually the database driver will have some method of doing encoding/decoding transparently for you and always give you unicode strings. Otherwise you will need to encode/decode by hand.
Use unicode strings in your application.
Right before the binary data leaves your application, use encode() on the string to encode to your desired encoding.
If your target encoding cannot represent some of your unicode characters, you may get UnicodeEncodeError. In this case do one of the following:
Use the second argument to encode() to ignore or replace characters that can't be represented in the target encoding;
Don't generate these characters in your application.
Find an alternate way of representing them. E.g., in XML, you can use a numeric character entity.
For files, you may use the codecs.open wrapper to do encoding for you transparently.
For database connections, the driver will often have an option to accept unicode strings and encode for you.
For network connections, you must generally encode by hand. Sometimes the payload will be generated by a library that will encode properly for you (e.g., writing XML).
Because you are correctly using the magic "coding comment," everything works as supposed.