Beautiful Soup Lxml

B

BeautifulSoup Parser - lxml

BeautifulSoup Parser – lxml

BeautifulSoup is a Python package for working with real-world and broken HTML,
just like As of version 4. x, it can use
different HTML parsers,
each of which has its advantages and disadvantages (see the link).
lxml can make use of BeautifulSoup as a parser backend, just like BeautifulSoup
can employ lxml as a parser. When using BeautifulSoup from lxml, however, the
default is to use Python’s integrated HTML parser in the
module.
In order to make use of the HTML5 parser of
html5lib instead, it is better
to go directly through the html5parser module in
A very nice feature of BeautifulSoup is its excellent support for encoding
detection which can provide better results for real-world HTML pages that
do not (correctly) declare their encoding.
lxml interfaces with BeautifulSoup through the
module. It provides three main functions: fromstring() and parse()
to parse a string or file using BeautifulSoup into an
document, and convert_tree() to convert an existing BeautifulSoup
tree into a list of top-level Elements.
Contents
Parsing with the soupparser
Entity handling
Using soupparser as a fallback
Using only the encoding detection
The functions fromstring() and parse() behave as known from
lxml. The first returns a root Element, the latter returns an
ElementTree.
There is also a legacy module called, which
mimics the interface provided by Fredrik Lundh’s ElementSoup
module. Note that the soupparser module was added in lxml 2. 0. 3.
Previous versions of lxml 2. x only have the ElementSoup module.
Here is a document full of tag soup, similar to, but not quite like, HTML:
>>> tag_soup = ”’… Hello</head><body onload=crash()>Hi all</p> <p>”’<br /> All you need to do is pass it to the fromstring() function:<br /> >>> from import fromstring<br /> >>> root = fromstring(tag_soup)<br /> To see what we have here, you can serialise it:<br /> >>> from import tostring<br /> >>> print(tostring(root, pretty_print=True)())<br /> <html><br /> <meta/><br /> <head><br /> <title>Hello

Hi all



Not quite what you’d expect from an HTML page, but, well, it was broken
already, right? The parser did its best, and so now it’s a tree.
To control how Element objects are created during the conversion
of the tree, you can pass a makeelement factory function to
parse() and fromstring(). By default, this is based on the
HTML parser defined in
For a quick comparison, libxml2 2. 9. 1 parses the same tag soup as
follows. The only difference is that libxml2 tries harder to adhere
to the structure of an HTML document and moves misplaced tags where
they (likely) belong. Note, however, that the result can vary between
parser versions.
By default, the BeautifulSoup parser also replaces the entities it
finds by their character equivalent.
>>> tag_soup = ‘©€-õƽ


>>> body = fromstring(tag_soup)(‘. //body’)
>>>
u’xa9u20ac-xf5u01bd’
If you want them back on the way out, you can just serialise with the
default encoding, which is ‘US-ASCII’.
>>> tostring(body)
‘©€-õƽ


>>> tostring(body, method=”html”)
‘©€-õƽ


Any other encoding will output the respective byte sequences.
>>> tostring(body, encoding=”utf-8″)
‘xc2xa9xe2x82xac-xc3xb5xc6xbd


>>> tostring(body, method=”html”, encoding=”utf-8″)
‘xc2xa9xe2x82xac-xc3xb5xc6xbd


>>> tostring(body, encoding=’unicode’)
u’xa9u20ac-xf5u01bd


>>> tostring(body, method=”html”, encoding=’unicode’)
u’xa9u20ac-xf5u01bd


The downside of using this parser is that it is much slower than
the C implemented HTML parser of libxml2 that lxml uses. So if
performance matters, you might want to consider using soupparser
only as a fallback for certain cases.
One common problem of lxml’s parser is that it might not get the
encoding right in cases where the document contains a tag
at the wrong place. In this case, you can exploit the fact that lxml
serialises much faster than most other HTML libraries for Python.
Just serialise the document to unicode and if that gives you an
exception, re-parse it with BeautifulSoup to see if that works
better.
>>> tag_soup = ”’… … … … Hello Wxc3xb6rld! … … Hi all… ”’
>>> import
>>> root = (tag_soup)
>>> try:… ignore = tostring(root, encoding=’unicode’)… except UnicodeDecodeError:… root = (tag_soup)
Even if you prefer lxml’s fast HTML parser, you can still benefit
from BeautifulSoup’s support for encoding detection in the
UnicodeDammit class. Once it succeeds in decoding the data,
you can simply pass the resulting Unicode string into lxml’s parser.
>>> try:… from bs4 import UnicodeDammit # BeautifulSoup 4…… def decode_html(html_string):… converted = UnicodeDammit(html_string)… if not converted. unicode_markup:… raise UnicodeDecodeError(… “Failed to detect encoding, tried [%s]”,… ‘, ‘(ied_encodings))… # print converted. original_encoding… return converted. unicode_markup…… except ImportError:… from BeautifulSoup import UnicodeDammit # BeautifulSoup 3…… converted = UnicodeDammit(html_string, isHTML=True)… unicode:… ‘, ‘(iedEncodings))… originalEncoding… unicode
>>> root = (decode_html(tag_soup))
BeautifulSoup Parser - lxml

BeautifulSoup Parser – lxml

BeautifulSoup is a Python package for working with real-world and broken HTML,
just like As of version 4. x, it can use
different HTML parsers,
each of which has its advantages and disadvantages (see the link).
lxml can make use of BeautifulSoup as a parser backend, just like BeautifulSoup
can employ lxml as a parser. When using BeautifulSoup from lxml, however, the
default is to use Python’s integrated HTML parser in the
module.
In order to make use of the HTML5 parser of
html5lib instead, it is better
to go directly through the html5parser module in
A very nice feature of BeautifulSoup is its excellent support for encoding
detection which can provide better results for real-world HTML pages that
do not (correctly) declare their encoding.
lxml interfaces with BeautifulSoup through the
module. It provides three main functions: fromstring() and parse()
to parse a string or file using BeautifulSoup into an
document, and convert_tree() to convert an existing BeautifulSoup
tree into a list of top-level Elements.
Contents
Parsing with the soupparser
Entity handling
Using soupparser as a fallback
Using only the encoding detection
The functions fromstring() and parse() behave as known from
lxml. The first returns a root Element, the latter returns an
ElementTree.
There is also a legacy module called, which
mimics the interface provided by Fredrik Lundh’s ElementSoup
module. Note that the soupparser module was added in lxml 2. 0. 3.
Previous versions of lxml 2. x only have the ElementSoup module.
Here is a document full of tag soup, similar to, but not quite like, HTML:
>>> tag_soup = ”’… Hello</head><body onload=crash()>Hi all</p> <p>”’<br /> All you need to do is pass it to the fromstring() function:<br /> >>> from import fromstring<br /> >>> root = fromstring(tag_soup)<br /> To see what we have here, you can serialise it:<br /> >>> from import tostring<br /> >>> print(tostring(root, pretty_print=True)())<br /> <html><br /> <meta/><br /> <head><br /> <title>Hello

Hi all



Not quite what you’d expect from an HTML page, but, well, it was broken
already, right? The parser did its best, and so now it’s a tree.
To control how Element objects are created during the conversion
of the tree, you can pass a makeelement factory function to
parse() and fromstring(). By default, this is based on the
HTML parser defined in
For a quick comparison, libxml2 2. 9. 1 parses the same tag soup as
follows. The only difference is that libxml2 tries harder to adhere
to the structure of an HTML document and moves misplaced tags where
they (likely) belong. Note, however, that the result can vary between
parser versions.
By default, the BeautifulSoup parser also replaces the entities it
finds by their character equivalent.
>>> tag_soup = ‘©€-õƽ


>>> body = fromstring(tag_soup)(‘. //body’)
>>>
u’xa9u20ac-xf5u01bd’
If you want them back on the way out, you can just serialise with the
default encoding, which is ‘US-ASCII’.
>>> tostring(body)
‘©€-õƽ


>>> tostring(body, method=”html”)
‘©€-õƽ


Any other encoding will output the respective byte sequences.
>>> tostring(body, encoding=”utf-8″)
‘xc2xa9xe2x82xac-xc3xb5xc6xbd


>>> tostring(body, method=”html”, encoding=”utf-8″)
‘xc2xa9xe2x82xac-xc3xb5xc6xbd


>>> tostring(body, encoding=’unicode’)
u’xa9u20ac-xf5u01bd


>>> tostring(body, method=”html”, encoding=’unicode’)
u’xa9u20ac-xf5u01bd


The downside of using this parser is that it is much slower than
the C implemented HTML parser of libxml2 that lxml uses. So if
performance matters, you might want to consider using soupparser
only as a fallback for certain cases.
One common problem of lxml’s parser is that it might not get the
encoding right in cases where the document contains a tag
at the wrong place. In this case, you can exploit the fact that lxml
serialises much faster than most other HTML libraries for Python.
Just serialise the document to unicode and if that gives you an
exception, re-parse it with BeautifulSoup to see if that works
better.
>>> tag_soup = ”’… … … … Hello Wxc3xb6rld! … … Hi all… ”’
>>> import
>>> root = (tag_soup)
>>> try:… ignore = tostring(root, encoding=’unicode’)… except UnicodeDecodeError:… root = (tag_soup)
Even if you prefer lxml’s fast HTML parser, you can still benefit
from BeautifulSoup’s support for encoding detection in the
UnicodeDammit class. Once it succeeds in decoding the data,
you can simply pass the resulting Unicode string into lxml’s parser.
>>> try:… from bs4 import UnicodeDammit # BeautifulSoup 4…… def decode_html(html_string):… converted = UnicodeDammit(html_string)… if not converted. unicode_markup:… raise UnicodeDecodeError(… “Failed to detect encoding, tried [%s]”,… ‘, ‘(ied_encodings))… # print converted. original_encoding… return converted. unicode_markup…… except ImportError:… from BeautifulSoup import UnicodeDammit # BeautifulSoup 3…… converted = UnicodeDammit(html_string, isHTML=True)… unicode:… ‘, ‘(iedEncodings))… originalEncoding… unicode
>>> root = (decode_html(tag_soup))
1. lxml is way faster than BeautifulSoup - this may not matter ...

1. lxml is way faster than BeautifulSoup – this may not matter …

> 1. lxml is way faster than BeautifulSoup – this may not matter if all you’re waiting for is the network. But if you’re parsing something on disk, this may be lxml’s HTML parser is garbage, so is BS’s, they will parse pages in non-obvious ways which do not reflect what you see in your browser, because your browser follows HTML5 tree ml5lib fixes that (and can construct both lxml and bs trees, and both libraries have html5lib integration), however it’s slow. I don’t know that there is a native compatible parser (there are plenty of native HTML5 parsers e. g. gumbo or html5ever but I don’t remember them being able to generate lxml or bs trees). > 2. Don’t forget to check the status code of r (atus_code or less generally)Alternatively (depending on use case) `r. raise_for_status()`. I’m still annoyed that there’s no way to ask requests to just check it outright. > Those with a background in coding might prefer the. cssselect method available in whatever object the parsed document results in. That’s obviously a tad slower than find/findall/xpath, but it’s oftentimes too convenient to pass cssselect simply translates CSS selectors to XPath, and while I don’t know for sure I’m guessing it has an expression cache, so it should not be noticeably slower than XPath (CSS selectors are not a hugely complex language anyway)

Frequently Asked Questions about beautiful soup lxml

What is lxml in beautiful soup?

lxml can make use of BeautifulSoup as a parser backend, just like BeautifulSoup can employ lxml as a parser. When using BeautifulSoup from lxml, however, the default is to use Python’s integrated HTML parser in the html. parser module.

Is lxml faster than BeautifulSoup?

lxml is way faster than BeautifulSoup – this may not matter if all you’re waiting for is the network. But if you’re parsing something on disk, this may be significant. … html5lib fixes that (and can construct both lxml and bs trees, and both libraries have html5lib integration), however it’s slow.Oct 24, 2017

What is the use of Beautiful Soup in Python?

Beautiful Soup is a Python library that is used for web scraping purposes to pull the data out of HTML and XML files. It creates a parse tree from page source code that can be used to extract data in a hierarchical and more readable manner.Dec 4, 2020

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