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Python Import Lxml

• November 16, 2021
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Installing lxml

Contents
Where to get it
Requirements
Installation
Building lxml from dev sources
Using lxml with python-libxml2
Source builds on MS Windows
Source builds on MacOS-X
lxml is generally distributed through PyPI.
Most Linux platforms come with some version of lxml readily
packaged, usually named python-lxml for the Python 2. x version
and python3-lxml for Python 3. x. If you can use that version,
the quickest way to install lxml is to use the system package
manager, e. g. apt-get on Debian/Ubuntu:
sudo apt-get install python3-lxml
For MacOS-X, a macport of lxml is available.
Try something like
sudo port install py27-lxml
To install a newer version or to install lxml on other systems,
see below.
You need Python 2. 7 or 3. 4+.
Unless you are using a static binary distribution (e. from a
Windows binary installer), lxml requires libxml2 and libxslt to
be installed, in particular:
libxml2 version 2. 9. 2 or later.
libxslt version 1. 1. 27 or later.
We recommend libxslt 1. 28 or later.
Newer versions generally contain fewer bugs and are therefore
recommended. XML Schema support is also still worked on in libxml2,
so newer versions will give you better compliance with the W3C spec.
To install the required development packages of these dependencies
on Linux systems, use your distribution specific installation tool,
e. apt-get on Debian/Ubuntu:
sudo apt-get install libxml2-dev libxslt-dev python-dev
For Debian based systems, it should be enough to install the known
build dependencies of the provided lxml package, e. g.
sudo apt-get build-dep python3-lxml
If your system does not provide binary packages or you want to install
a newer version, the best way is to get the pip package management tool
(or use a virtualenv) and
run the following:
pip install lxml
If you are not using pip in a virtualenv and want to install lxml globally
instead, you have to run the above command as admin, e. on Linux:
sudo pip install lxml
To install a specific version, either download the distribution
manually and let pip install that, or pass the desired version
to pip:
pip install lxml==3. 4. 2
To speed up the build in test environments, e. on a continuous
integration server, disable the C compiler optimisations by setting
the CFLAGS environment variable:
CFLAGS=”-O0″ pip install lxml
(The option reads “minus Oh Zero”, i. e. zero optimisations. )
MS Windows
For MS Windows, recent lxml releases feature community donated
binary distributions, although you might still want to take a look
at the related FAQ entry.
If you fail to build lxml on your MS Windows system from the signed
and tested sources that we release, consider using the binary builds
from PyPI or the unofficial Windows binaries
that Christoph Gohlke generously provides.
Linux
On Linux (and most other well-behaved operating systems), pip will
manage to build the source distribution as long as libxml2 and libxslt
are properly installed, including development packages, i. header files,
etc. See the requirements section above and use your system package
management tool to look for packages like libxml2-dev or
libxslt-devel. If the build fails, make sure they are installed.
Alternatively, setting STATIC_DEPS=true will download and build
both libraries automatically in their latest version, e. g.
STATIC_DEPS=true pip install lxml.
MacOS-X
On MacOS-X, use the following to build the source distribution,
and make sure you have a working Internet connection, as this will
download libxml2 and libxslt in order to build them:
STATIC_DEPS=true sudo pip install lxml
If you want to build lxml from the GitHub repository, you should read
how to build lxml from source (or the file doc/ in the
source tree). Building from developer sources or from modified
distribution sources requires Cython to translate the lxml sources
into C code. The source distribution ships with pre-generated C
source files, so you do not need Cython installed to build from
release sources.
If you have read these instructions and still cannot manage to install lxml,
you can check the archives of the mailing list to see if your problem is
known or otherwise send a mail to the list.
If you want to use lxml together with the official libxml2 Python
bindings (maybe because one of your dependencies uses it), you must
build lxml statically. Otherwise, the two packages will interfere in
places where the libxml2 library requires global configuration, which
can have any kind of effect from disappearing functionality to crashes
in either of the two.
To get a static build, either pass the –static-deps option to the
script, or run pip with the STATIC_DEPS or
STATICBUILD environment variable set to true, i. e.
STATIC_DEPS=true pip install lxml
The STATICBUILD environment variable is handled equivalently to
the STATIC_DEPS variable, but is used by some other extension
packages, too.
Most MS Windows systems lack the necessarily tools to build software,
starting with a C compiler already. Microsoft leaves it to users to
install and configure them, which is usually not trivial and means
that distributors cannot rely on these dependencies being available
on a given system. In a way, you get what you’ve paid for and make
others pay for it.
Due to the additional lack of package management of this platform,
it is best to link the library dependencies statically if you decide
to build from sources, rather than using a binary installer. For
that, lxml can use the binary distribution of libxml2 and libxslt, which it downloads
automatically during the static build. It needs both libxml2 and
libxslt, as well as iconv and zlib, which are available from the
same download site. Further build instructions are in the
source build documentation.
If you are not using macports or want to use a more recent lxml
release, you have to build it yourself. While the pre-installed system
libraries of libxml2 and libxslt are less outdated in recent MacOS-X
versions than they used to be, so lxml should work with them out of the
box, it is still recommended to use a static build with the most recent
library versions.
Luckily, lxml’s script has built-in support for building
and integrating these libraries statically during the build. Please
read the
MacOS-X build instructions.

Implementing web scraping using lxml in Python – GeeksforGeeks

Web scraping basically refers to fetching only some important piece of information from one or more websites. Every website has recognizable structure/pattern of HTML elements. Steps to perform web scraping:1. Send a link and get the response from the sent link 2. Then convert response object to a byte string. 3. Pass the byte string to ‘fromstring’ method in html class in lxml module. 4. Get to a particular element by xpath. 5. Use the content according to your need. Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics. To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level CourseFor accomplishing this task some third-party packages is needed to install. Use pip to install wheel() files. pip install requests
pip install lxmlxpath to the element is also needed from which data will be scrapped. An easy way to do this is –1. Right-click the element in the page which has to be scrapped and go-to “Inspect”. 2. Right-click the element on source-code to the right. 3. Copy xpath. Here is a simple implementation on “geeksforgeeks homepage“: Python3import requestsfrom lxml import htmlpath = ‘//*[@id =”post-183376″]/div / p’response = (url)byte_data = ntentsource_code = omstring(byte_data)tree = (path)print(tree[0]. text_content())The above code scrapes the paragraph in first article from “geeksforgeeks homepage” homepage. Here’s the sample output. The output may not be same for everyone as the article would have: “Consider the following C/C++ programs and try to guess the output?
Output of all of the above programs is unpredictable (or undefined).
The compilers (implementing… Read More »”Here’s another example for data scraped from Wiki-web-scraping. Python3import requestsfrom lxml import htmlpath = ‘//*[@id =”mw-content-text”]/div / p[1]’response = (link)byte_string = ntentsource_code = omstring(byte_string)tree = (path)print(tree[0]. text_content())Output: Web scraping, web harvesting, or web data extraction is data scraping used for extracting data from websites. [1] Web scraping software may access the World Wide Web directly using the Hypertext Transfer Protocol, or through a web browser. While web scraping can be done manually by a software user, the term typically refers to automate processes implemented using a bot or web crawler. It is a form of copying, in which specific data is gathered and copied from the web, typically into a central local database or spreadsheet, for later retrieval or analysis.

Introduction to the Python lxml Library – Stack Abuse

lxml is a Python library which allows for easy handling of XML and HTML files, and can also be used for web scraping. There are a lot of off-the-shelf XML parsers out there, but for better results, developers sometimes prefer to write their own XML and HTML parsers. This is when the lxml library comes to play. The key benefits of this library are that it’s ease of use, extremely fast when parsing large documents, very well documented, and provides easy conversion of data to Python data types, resulting in easier file manipulation.
In this tutorial, we will deep dive into Python’s lxml library, starting with how to set it up for different operating systems, and then discussing its benefits and the wide range of functionalities it offers.
Installation
There are multiple ways to install lxml on your system. We’ll explore some of them below.
Using Pip
Pip is a Python package manager which is used to download and install Python libraries to your local system with ease i. e. it downloads and installs all the dependencies for the package you’re installing, as well.
If you have pip installed on your system, simply run the following command in terminal or command prompt:
$ pip install lxml
Using apt-get
If you’re using MacOS or Linux, you can install lxml by running this command in your terminal:
$ sudo apt-get install python-lxml
Using easy_install
You probably won’t get to this part, but if none of the above commands works for you for some reason, try using easy_install:
$ easy_install lxml
Note: If you wish to install any particular version of lxml, you can simply state it when you run the command in the command prompt or terminal like this, lxml==3. x. y.
By now, you should have a copy of the lxml library installed on your local machine. Let’s now get our hands dirty and see what cool things can be done using this library.
Functionality
To be able to use the lxml library in your program, you first need to import it. You can do that by using the following command:
from lxml import etree as et
This will import the etree module, the module of our interest, from the lxml library.
Creating HTML/XML Documents
Using the etree module, we can create XML/HTML elements and their subelements, which is a very useful thing if we’re trying to write or manipulate an HTML or XML file. Let’s try to create the basic structure of an HTML file using etree:
root = et. Element(‘html’, version=”5. 0″)
# Pass the parent node, name of the child node,
# and any number of optional attributes
bElement(root, ‘head’)
bElement(root, ‘title’, bgcolor=”red”, fontsize=’22’)
bElement(root, ‘body’, fontsize=”15″)
In the code above, you need to know that the Element function requires at least one parameter, whereas the SubElement function requires at least two. This is because the Element function only ‘requires’ the name of the element to be created, whereas the SubElement function requires the name of both the root node and the child node to be created.
It’s also important to know that both these functions only have a lower bound to the number of arguments they can accept, but no upper bound because you can associate as many attributes with them as you want. To add an attribute to an element, simply add an additional parameter to the (Sub)Element function and specify your attribute in the form of attributeName=’attribute value’.
Let’s try to run the code we wrote above to gain a better intuition regarding these functions:
# Use pretty_print=True to indent the HTML output
print (string(root, pretty_print=True)(“utf-8”))
Output:


This is the body of that file and would contain paragraphs etc
Check if an Element has Children
Next, there are two very important things that we should be able to check, as that is required in a lot of web scraping applications for exception handling. First thing we’d like to check is whether or not an element has children, and second is whether or not a node is an Element.
Let’s do that for the nodes we created above:
if len(root) > 0:
print(“True”)
else:
print(“False”)
The above code will output “True” since the root node does have child nodes. However, if we check the same thing for the root’s child nodes, like in the code below, the output will be “False”.
for i in range(len(root)):
if (len(root[i]) > 0):
False
Now let’s do the same thing to see if each of the nodes is an Element or not:
print(element(root[i]))
True
The iselement method is helpful for determining if you have a valid Element object, and thus if you can continue traversing it using the methods we’ve shown here.
Check if an Element has a Parent
Just now, we showed how to go down the hierarchy, i. how to check if an element has children or not, and now in this section we will try to go up the hierarchy, i. how to check and get the parent of a child node.
print(tparent())
print(root[0]. getparent())
print(root[1]. getparent())
The first line should return nothing (aka None) as the root node itself doesn’t have any parent. The other two should both point to the root element i. the HTML tag. Let’s check the output to see if it is what we expect:

Retrieving Element Siblings
In this section we will learn how to traverse sideways in the hierarchy, which retrieves an element’s siblings in the tree.
Traversing the tree sideways is quite similar to navigating it vertically. For the latter, we used the getparent and the length of the element, for the former, we’ll use getnext and getprevious functions. Let’s try them on nodes that we previously created to see how they work:
# root[1] is the `title` tag
print(root[1]. getnext()) # The tag after the `title` tag
print(root[1]. getprevious()) # The tag before the `title` tag


Here you can see that root[1]. getnext() retrieved the “body” tag since it was the next element, and root[1]. getprevious() retrieved the “head” tag.
Similarly, if we had used the getprevious function on root, it would have returned None, and if we had used the getnext function on root[2], it would also have returned None.
Parsing XML from a String
Moving on, if we have an XML or HTML file and we wish to parse the raw string in order to obtain or manipulate the required information, we can do so by following the example below:
root = (‘This is an HTML fileThis is the head of that fileThis is the body of that file and would contain paragraphs etc‘)
root[1] = “The title text has changed! ”
print(string(root, xml_declaration=True)(‘utf-8’))

This is an HTML fileThis is the head of that fileThis is the body of that file and would contain paragraphs etc
As you can see, we successfully changed some text in the HTML document. The XML doctype declaration was also automatically added because of the xml_declaration parameter that we passed to the tostring function.
Searching for Elements
The last thing we’re going to discuss is quite handy when parsing XML and HTML files. We will be checking ways through which we can see if an Element has any particular type of children, and if it does what do they contain.
This has many practical use-cases, such as finding all of the link elements on a particular web page.
print((‘a’)) # No tags exist, so this will be `None`
print((‘head’))
print(ndtext(‘title’)) # Directly retrieve the the title tag’s text
This is the title of that file
Conclusion
In the above tutorial, we started with a basic introduction to what lxml library is and what it is used for. After that, we learned how to install it on different environments like Windows, Linux, etc. Moving on, we explored different functionalities that could help us in traversing through the HTML/XML tree vertically as well as sideways. In the end, we also discussed ways to find elements in our tree, and as well as obtain information from them.

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