There are multiple aspects to this problem. The fundamental question is which character set you want to output into. You may also have to figure out the input character set.
Printing (with either print
or write
) into a file with an explicit encoding="..."
will translate Python's internal Unicode representation into that encoding. If the output contains characters which are not supported by that encoding, you will get an UnicodeEncodeError
. For example, you can't write Russian or Chinese or Indic or Hebrew or Arabic or emoji or ... anything except a restricted set of some 200+ Western characters to a file whose encoding is "cp1252"
because this limited 8-bit character set has no way to represent these characters.
Basically the same problem will occur with any 8-bit character set, including nearly all the legacy Windows code pages (437, 850, 1250, 1251, etc etc), though some of them support some additional script in addition to or instead of English (1251 supports Cyrillic, for example, so you can write Russian, Ukrainian, Serbian, Bulgarian, etc). An 8-bit encoding has only a maximum of 256 character codes and no way to represent a character which isn't among them.
Perhaps now would be a good time to read Joel Spolsky's The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)
On platforms where the terminal is not capable of printing Unicode (only Windows these days really, though if you're into retrocomputing, this problem was also prevalent on other platforms in the previous millennium) attempting to print
Unicode strings can also produce this error, or output mojibake. If you see something like Héllö
instead of Héllö
, this is your issue.
In short, then, you need to know:
What is the character set of the page you scraped, or the data you received? Was it correctly scraped? Did the originator correctly identify its encoding, or are you able to otherwise obtain this information (or guess it)? Some web sites incorrectly declare a different character set than the page actually contains, some sites have incorrectly configured the connection between the web server and a back-end database. See e.g. scrape with correct character encoding (python requests + beautifulsoup) for a more detailed example with some solutions.
What is the character set you want to write? If printing to the screen, is your terminal correctly configured, and is your Python interpreter configured identically?
Perhaps see also How to display utf-8 in windows console
If you are here, probably the answer to one of these questions is not "UTF-8". This is increasingly becoming the prevalent encoding for web pages, too, though the former standard was ISO-8859-1 (aka Latin-1) and more recently Windows code page 1252.
Going forward, you basically want all your textual data to be Unicode, outside of a few fringe use cases. Generally, that means UTF-8, though on Windows (or if you need Java compatibility), UTF-16 is also vaguely viable, albeit somewhat cumbersome. (There are several other Unicode serialization formats, which may be useful in specialized circumstances. UTF-32 is technically trivial, but takes up a lot more memory; UTF-7 is used in a few network protocols where 7-bit ASCII is required for transport.)
Perhaps see also https://utf8everywhere.org/
Naturally, if you are printing to a file, you also need to examine that file using a tool which can correctly display it. A common pilot error is to open the file using a tool which only displays the currently selected system encoding, or one which tries to guess the encoding, but guesses wrong. Again, a common symptom when viewing UTF-8 text using Windows code page 1252 would result, for example, in Héllö
displaying as Héllö
.
If the encoding of character data is unknown, there is no simple way to automatically establish it. If you know what the text is supposed to represent, you can perhaps infer it, but this is typically a manual process with some guesswork involved. (Automatic tools like chardet
and ftfy
can help, but they get it wrong some of the time, too.)
To establish which encoding you are looking at, it can be helpful if you can identify the individual bytes in a character which isn't displayed correctly. For example, if you are looking at H\x8ell\x9a
but expect it to represent Héllö
, you can look up the bytes in a translation table. I have published one such table at https://tripleee.github.io/8bit where you can see that in this example, it's probably one of the legacy Mac 8-bit character sets; with more data points, perhaps you can narrow it down to just one of them (and if not, any one of them will do in practice, since all the code points you care about map to the same Unicode characters).
Python 3 on most platforms defaults to UTF-8 for all input and output, but on Windows, this is commonly not the case. It will then instead default to the system's default encoding (still misleadingly called "ANSI code page" in some Microsoft documentation), which depends on a number of factors. On Western systems, the default encoding out of the box is commonly Windows code page 1252.
(Earlier Python versions had somewhat different expectations, and in Python 2, the internal string representation was not Unicode.)
If you are on Windows and write UTF-8 to a text file, maybe specify encoding="utf-8-sig"
which adds a BOM sequence at the beginning of the file. This is strictly speaking not necessary or correct, but some Windows tools need it to correctly identify the encoding.
Several of the earlier answers here suggest blindly applying some encoding, but hopefully this should help you understand how that's not generally the correct approach, and how to figure out - rather than guess - which encoding to use.