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Web Scraping with Beautiful Soup — Searching Nodes

We can get data from web pages with Beautiful Soup.

It lets us parse the DOM and extract the data we want.

In this article, we’ll look at how to scrape HTML documents with Beautiful Soup.

Searching Strings with Regex

We can search strings with regex.

For example, we can write:

from bs4 import BeautifulSoup
import re
html_doc = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""

soup = BeautifulSoup(html_doc, 'html.parser')
print(soup.find_all(string=re.compile("Dormouse")))

We call re.compile to create our regex.

Also, we can search for strings with a function:

from bs4 import BeautifulSoup
import re
html_doc = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""

def is_the_only_string_within_a_tag(s):
    return (s == s.parent.string)

soup = BeautifulSoup(html_doc, 'html.parser')
print(soup.find_all(string=is_the_only_string_within_a_tag))

We get the string from the node with s.parent.string .

s is the string node we’re searching for.

The limit Argument

We can limit the number of items returned with find_all with the limit argument.

For example, we can write:

from bs4 import BeautifulSoup
import re
html_doc = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""

soup = BeautifulSoup(html_doc, 'html.parser')
print(soup.find_all("a", limit=2))

And we see:

[<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>, <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>]

logged.

The recursive Argument

We can set whether to search for elements recursively with the recursive argument.

For example, if we want to disable recursive search, we write:

from bs4 import BeautifulSoup
import re
html_doc = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""

soup = BeautifulSoup(html_doc, 'html.parser')
print(soup.html.find_all("title", recursive=False))

then we get an empty array since we turn off recursive search.

This is because title has descendants but we turned off recursive search so we won’t get them.

find()

We can find the first element with the given selector with find :

from bs4 import BeautifulSoup
import re
html_doc = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""

soup = BeautifulSoup(html_doc, 'html.parser')
print(soup.find('title'))

Then we get:

<title>The Dormouse's story</title>

printed.

We can chain find calls:

from bs4 import BeautifulSoup
import re
html_doc = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""

soup = BeautifulSoup(html_doc, 'html.parser')
print(soup.find("head").find("title"))

Conclusion

We can search for various elements with Beautiful Soup.

Posted in Beautiful Soup, Python