Python XML processing with lxml

To create or change an attribute named A to value V in an Element instance E, use this method:

E.set ( A, V )

Here's an example.

>>> node = etree.Element ( 'div', id='u401' )
>>> etree.tostring(node)
'<div id="u401"/>'
>>> node.set ( 'class', 'flyer' )
>>> etree.tostring(node)
'<div id="u401" class="flyer"/>'
>>> node.set ( 'class', 'broadside' )
>>> etree.tostring ( node )
'<div id="u401" class="broadside"/>'
>>> 

This method is one of two ways to create or change an attribute value. The other method is to store values into the .attrib dictionary of the Element instance.