Convert XML/HTML Entities into Unicode String in Python [duplicate]

https://stackoverflow.com/questions/57708

09-06-2019
|

Question

This question already has an answer here:

Decode HTML entities in Python string? 5 answers

I'm doing some web scraping and sites frequently use HTML entities to represent non ascii characters. Does Python have a utility that takes a string with HTML entities and returns a unicode type?

For example:

I get back:

&#x01ce;

which represents an "ǎ" with a tone mark. In binary, this is represented as the 16 bit 01ce. I want to convert the html entity into the value u'\u01ce'

Solution

The standard lib’s very own HTMLParser has an undocumented function unescape() which does exactly what you think it does:

import HTMLParser
h = HTMLParser.HTMLParser()
h.unescape('&copy; 2010') # u'\xa9 2010'
h.unescape('&#169; 2010') # u'\xa9 2010'

OTHER TIPS

Python has the htmlentitydefs module, but this doesn't include a function to unescape HTML entities.

Python developer Fredrik Lundh (author of elementtree, among other things) has such a function on his website, which works with decimal, hex and named entities:

import re, htmlentitydefs

##
# Removes HTML or XML character references and entities from a text string.
#
# @param text The HTML (or XML) source text.
# @return The plain text, as a Unicode string, if necessary.

def unescape(text):
    def fixup(m):
        text = m.group(0)
        if text[:2] == "&#":
            # character reference
            try:
                if text[:3] == "&#x":
                    return unichr(int(text[3:-1], 16))
                else:
                    return unichr(int(text[2:-1]))
            except ValueError:
                pass
        else:
            # named entity
            try:
                text = unichr(htmlentitydefs.name2codepoint[text[1:-1]])
            except KeyError:
                pass
        return text # leave as is
    return re.sub("&#?\w+;", fixup, text)

Use the builtin unichr -- BeautifulSoup isn't necessary:

>>> entity = '&#x01ce'
>>> unichr(int(entity[3:],16))
u'\u01ce'

An alternative, if you have lxml:

>>> import lxml.html
>>> lxml.html.fromstring('&#x01ce').text
u'\u01ce'

If you are on Python 3.4 or newer, you can simply use the html.unescape:

import html

s = html.unescape(s)

You could find an answer here -- Getting international characters from a web page?

EDIT: It seems like BeautifulSoup doesn't convert entities written in hexadecimal form. It can be fixed:

import copy, re
from BeautifulSoup import BeautifulSoup

hexentityMassage = copy.copy(BeautifulSoup.MARKUP_MASSAGE)
# replace hexadecimal character reference by decimal one
hexentityMassage += [(re.compile('&#x([^;]+);'), 
                     lambda m: '&#%d;' % int(m.group(1), 16))]

def convert(html):
    return BeautifulSoup(html,
        convertEntities=BeautifulSoup.HTML_ENTITIES,
        markupMassage=hexentityMassage).contents[0].string

html = '<html>&#x01ce;&#462;</html>'
print repr(convert(html))
# u'\u01ce\u01ce'

EDIT:

unescape() function mentioned by @dF which uses htmlentitydefs standard module and unichr() might be more appropriate in this case.

This is a function which should help you to get it right and convert entities back to utf-8 characters.

def unescape(text):
   """Removes HTML or XML character references 
      and entities from a text string.
   @param text The HTML (or XML) source text.
   @return The plain text, as a Unicode string, if necessary.
   from Fredrik Lundh
   2008-01-03: input only unicode characters string.
   http://effbot.org/zone/re-sub.htm#unescape-html
   """
   def fixup(m):
      text = m.group(0)
      if text[:2] == "&#":
         # character reference
         try:
            if text[:3] == "&#x":
               return unichr(int(text[3:-1], 16))
            else:
               return unichr(int(text[2:-1]))
         except ValueError:
            print "Value Error"
            pass
      else:
         # named entity
         # reescape the reserved characters.
         try:
            if text[1:-1] == "amp":
               text = "&amp;amp;"
            elif text[1:-1] == "gt":
               text = "&amp;gt;"
            elif text[1:-1] == "lt":
               text = "&amp;lt;"
            else:
               print text[1:-1]
               text = unichr(htmlentitydefs.name2codepoint[text[1:-1]])
         except KeyError:
            print "keyerror"
            pass
      return text # leave as is
   return re.sub("&#?\w+;", fixup, text)

Not sure why the Stack Overflow thread does not include the ';' in the search/replace (i.e. lambda m: '&#%d*;*') If you don't, BeautifulSoup can barf because the adjacent character can be interpreted as part of the HTML code (i.e. &#39B for &#39Blackout).

This worked better for me:

import re
from BeautifulSoup import BeautifulSoup

html_string='<a href="/cgi-bin/article.cgi?f=/c/a/2010/12/13/BA3V1GQ1CI.DTL"title="">&#x27;Blackout in a can; on some shelves despite ban</a>'

hexentityMassage = [(re.compile('&#x([^;]+);'), 
lambda m: '&#%d;' % int(m.group(1), 16))]

soup = BeautifulSoup(html_string, 
convertEntities=BeautifulSoup.HTML_ENTITIES, 
markupMassage=hexentityMassage)

The int(m.group(1), 16) converts the number (specified in base-16) format back to an integer.
m.group(0) returns the entire match, m.group(1) returns the regexp capturing group
Basically using markupMessage is the same as:
html_string = re.sub('&#x([^;]+);', lambda m: '&#%d;' % int(m.group(1), 16), html_string)

Another solution is the builtin library xml.sax.saxutils (both for html and xml). However, it will convert only &gt, &amp and &lt.

from xml.sax.saxutils import unescape

escaped_text = unescape(text_to_escape)

Here is the Python 3 version of dF's answer:

import re
import html.entities

def unescape(text):
    """
    Removes HTML or XML character references and entities from a text string.

    :param text:    The HTML (or XML) source text.
    :return:        The plain text, as a Unicode string, if necessary.
    """
    def fixup(m):
        text = m.group(0)
        if text[:2] == "&#":
            # character reference
            try:
                if text[:3] == "&#x":
                    return chr(int(text[3:-1], 16))
                else:
                    return chr(int(text[2:-1]))
            except ValueError:
                pass
        else:
            # named entity
            try:
                text = chr(html.entities.name2codepoint[text[1:-1]])
            except KeyError:
                pass
        return text # leave as is
    return re.sub("&#?\w+;", fixup, text)

The main changes concern htmlentitydefs that is now html.entities and unichr that is now chr. See this Python 3 porting guide.

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