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Python Lxml

12/7/2021
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If your system does not provide binary packages or you want to installa newer version, the best way is to get the pip package management tool(or use a virtualenv) andrun the following:

  1. Python Lxml Parse
  2. Lxml Library Python
  1. Contribute to mariosemes/PornHub-downloader-python development by creating an account on GitHub. Bump lxml from 4.5.1 to 4.6.3.
  2. Welcome to Python 101!¶ Learn how to program with Python 3 from beginning to end. Python 101 starts off with the fundamentals of Python and then builds onto what you’ve learned from there. The audience of this book is primarily people who have programmed in the past but want to learn Python.

If you are not using pip in a virtualenv and want to install lxml globallyinstead, you have to run the above command as admin, e.g. on Linux:

To install a specific version, either download the distributionmanually and let pip install that, or pass the desired versionto pip:

Python lxml Python lxml is the most feature-rich and easy-to-use library for processing XML and HTML data. Python scripts are written to perform many tasks like Web scraping and parsing XML. In this lesson, we will study about python lxml library and how we can use it to parse XML data and perform web scraping as well. In this article, you'll learn the basics of parsing an HTML document using Python and the LXML library. Introduction Data is the most important ingredient in programming. It comes in all shapes and forms. Sometimes it is placed inside documents such as CSV or JSON, but sometimes it is stored on the internet or in HTML Parsing using Python and LXML Read More ». Python-lxml4.5.0-1arm64.deb: pythonic binding for the libxml2 and libxslt libraries: Ubuntu Updates Universe amd64 Official: python-lxml4.5.0-1ubuntu0.3amd64.deb: pythonic binding for the libxml2 and libxslt libraries: Ubuntu Updates Universe arm64 Official: python-lxml4.5.0-1ubuntu0.3arm64.deb: pythonic binding for the libxml2.

To speed up the build in test environments, e.g. on a continuousintegration server, disable the C compiler optimisations by settingthe CFLAGS environment variable:

(The option reads 'minus Oh Zero', i.e. zero optimisations.)

MS Windows

For MS Windows, recent lxml releases feature community donatedbinary distributions, although you might still want to take a lookat the related FAQ entry.If you fail to build lxml on your MS Windows system from the signedand tested sources that we release, consider using the binary buildsfrom PyPI or the unofficial Windows binariesthat Christoph Gohlke generously provides.

Linux

On Linux (and most other well-behaved operating systems), pip willmanage to build the source distribution as long as libxml2 and libxsltare properly installed, including development packages, i.e. header files,etc. See the requirements section above and use your system packagemanagement tool to look for packages like libxml2-dev orlibxslt-devel. If the build fails, make sure they are installed.

Alternatively, setting STATIC_DEPS=true will download and buildboth 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 willdownload libxml2 and libxslt in order to build them:

In Part I, we looked at some of Python’s built-in XML parsers. In this chapter, we will look at the fun third-party package, lxml from codespeak. It uses the ElementTree API, among other things. The lxml package has XPath and XSLT support, includes an API for SAX and a C-level API for compatibility with C/Pyrex modules. Here is what we will cover:

  • How to Parse XML with lxml
  • A Refactoring example
  • How to Parse XML with lxml.objectify
  • How to Create XML with lxml.objectify

For this chapter, we will use the examples from the minidom parsing example and see how to parse those with lxml. Here’s an XML example from a program that was written for keeping track of appointments:

Let’s learn how to parse this with lxml!

Parsing XML with lxml¶

The XML above shows two appointments. The beginning time is in seconds since the epoch; the uid is generated based on a hash of the beginning time and a key; the alarm time is the number of seconds since the epoch, but should be less than the beginning time; and the state is whether or not the appointment has been snoozed, dismissed or not. The rest of the XML is pretty self-explanatory. Now let’s see how to parse it.

Python Lxml Parse

First off, we import the needed modules, namely the etree module from the lxml package and the StringIO function from the built-in StringIO module. Our parseXML function accepts one argument: the path to the XML file in question. We open the file, read it and close it. Now comes the fun part! We use etree’s parse function to parse the XML code that is returned from the StringIO module. For reasons I don’t completely understand, the parse function requires a file-like object.

Anyway, next we iterate over the context (i.e. the lxml.etree.iterparse object) and extract the tag elements. We add the conditional if statement to replace the empty fields with the word “None” to make the output a little clearer. And that’s it.

Parsing the Book Example¶

Lxml Library Python

Well, the result of that example was kind of boring. Most of the time, you want to save the data you extract and do something with it, not just print it out to stdout. So for our next example, we’ll create a data structure to contain the results. Our data structure for this example will be a list of dicts. We’ll use the MSDN book example here from the earlier chapter again. Save the following XML as example.xml

Now let’s parse this XML and put it in our data structure!

This example is pretty similar to our last one, so we’ll just focus on the differences present here. Right before we start iterating over the context, we create an empty dictionary object and an empty list. Then inside the loop, we create our dictionary like this:

The text is either elem.text or None. Finally, if the tag happens to be book, then we’re at the end of a book section and need to add the dict to our list as well as reset the dict for the next book. As you can see, that is exactly what we have done. A more realistic example would be to put the extracted data into a Book class. I have done the latter with json feeds before.

Now we’re ready to learn how to parse XML with lxml.objectify!

Parsing XML with lxml.objectify¶

The lxml module has a module called objectify that can turn XML documents into Python objects. I find “objectified” XML documents very easy to work with and I hope you will too. You may need to jump through a hoop or two to install it as pip doesn’t work with lxml on Windows. Be sure to go to the Python Package index and look for a version that’s been made for your version of Python. Also note that the latest pre-built installer for lxml only supports Python 3.2 (at the time of writing), so if you have a newer version of Python, you may have some difficulty getting lxml installed for your version.

Anyway, once you have it installed, we can start going over this wonderful piece of XML again:

Now we need to write some code that can parse and modify the XML. Let’s take a look at this little demo that shows a bunch of the neat abilities that objectify provides.

The code is pretty well commented, but we’ll spend a little time going over it anyway. First we pass it our sample XML file and objectify it. If you want to get access to a tag’s attributes, use the attrib property. It will return a dictionary of the attributes of the tag. To get to sub-tag elements, you just use dot notation. As you can see, to get to the begin tag’s value, we can just do something like this:

One thing to be aware of is if the value happens to have leading zeroes, the returned value may have them truncated. If that is important to you, then you should use the following syntax instead:

If you need to iterate over the children elements, you can use the iterchildren method. You may have to use a nested for loop structure to get everything. Changing an element’s value is as simple as just assigning it a new value.

Now we’re ready to learn how to create XML using lxml.objectify.

Creating XML with lxml.objectify¶

The lxml.objectify sub-package is extremely handy for parsing and creating XML. In this section, we will show how to create XML using the lxml.objectify module. We’ll start with some simple XML and then try to replicate it. Let’s get started!

We will continue using the following XML for our example:

Python Lxml

Let’s see how we can use lxml.objectify to recreate this XML:

Let’s break this down a bit. We will start with the create_xml function. In it we create an XML root object using the objectify module’s fromstring function. The root object will contain zAppointment as its tag. We set the root’s reminder attribute and then we call our create_appt function using a dictionary for its argument. In the create_appt function, we create an instance of an Element (technically, it’s an ObjectifiedElemen**t) that we assign to our **appt variable. Here we use dot-notatio**n to create the tags for this element. Finally we return the **appt element back and append it to our root object. We repeat the process for the second appointment instance.

The next section of the create_xml function will remove the lxml annotation. If you do not do this, your XML will end up looking like the following:

To remove all that unwanted annotation, we call the following two functions:

The last piece of the puzzle is to get lxml to generate the XML itself. Here we use lxml’s etree module to do the hard work:

The tostring function will return a nice string of the XML and if you set pretty_print to True, it will usually return the XML in a nice format too. The xml_declaration keyword argument tells the etree module whether or not to include the first declaration line (i.e. <?xml version=”1.0” ?>.

Wrapping Up¶

Now you know how to use lxml’s etree and objectify modules to parse XML. You also know how to use objectify to create XML. Knowing how to use more than one module to accomplish the same task can be valuable in seeing how to approach the same problem from different angles. It will also help you choose the tool that you’re most comfortable with.

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