How to work with unicode in Python

问题

I am trying to clean all of the HTML out of a string so the final output is a text file. I have some some research on the various 'converters' and am starting to lean towards creating my own dictionary for the entities and symbols and running a replace on the string. I am considering this because I want to automate the process and there is a lot of variability in the quality of the underlying html. To begin comparing the speed of my solution and one of the alternatives for example pyparsing I decided to test replace of \xa0 using the string method replace. I get a

UnicodeDecodeError: 'ascii' codec can't decode byte 0xa0 in position 0: ordinal not in range(128)

The actual line of code was

s=unicodestring.replace('\xa0','')

Anyway-I decided that I needed to preface it with an r so I ran this line of code:

s=unicodestring.replace(r'\xa0','')

It runs without error but I when I look at a slice of s I see that the \xaO is still there

回答1:

may be you should be doing

s=unicodestring.replace(u'\xa0',u'')

回答2:

s=unicodestring.replace('\xa0','')

..is trying to create the unicode character \xa0, which is not valid in an ASCII sctring (the default string type in Python until version 3.x)

The reason r'\xa0' did not error is because in a raw string, escape sequences have no effect. Rather than trying to encode \xa0 into the unicode character, it saw the string as a "literal backslash", "literal x" and so on..

The following are the same:

>>> r'\xa0'
'\\xa0'
>>> '\\xa0'
'\\xa0'

This is something resolved in Python v3, as the default string type is unicode, so you can just do..

>>> '\xa0'
'\xa0'

I am trying to clean all of the HTML out of a string so the final output is a text file

I would strongly recommend BeautifulSoup for this. Writing an HTML cleaning tool is difficult (given how horrible most HTML is), and BeautifulSoup does a great job at both parsing HTML, and dealing with Unicode..

>>> from BeautifulSoup import BeautifulSoup
>>> soup = BeautifulSoup("<html><body><h1>Hi</h1></body></html>")
>>> print soup.prettify()
<html>
 <body>
  <h1>
   Hi
  </h1>
 </body>
</html>

回答3:

Look at the codecs standard library, specifically the encode and decode methods provided in the Codec base class.

There's also a good article here that puts it all together.

回答4:

Instead of this, it's better to use standard python features.

For example:

string = unicode('Hello, \xa0World', 'utf-8', 'replace')

string = unicode('Hello, \xa0World', 'utf-8', 'ignore')

where replace will replace \xa0 to \\xa0.

But if \xa0 is really not meaningful for you and you want to remove it then use ignore.

回答5:

Just a note regarding HTML cleaning. It is very very hard, since

<
body
>

Is a valid way to write HTML. Just an fyi.

回答6:

You can convert it to unicode in this way:

print u'Hello, \xa0World'  # print Hello,  World

来源：https://stackoverflow.com/questions/752998/how-to-work-with-unicode-in-python

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python

string

unicode

replace

unicode-string