lxml: add namespace to input file

Question

I am parsing an xml file generated by an external program. I would then like to add custom annotations to this file, using my own namespace. My input looks as below:

Answer 1

I wrote this function to add a namespace to the root element:

def addns(tree, alias, uri):                
    root = tree.getroot()
    nsmap = root.nsmap
    nsmap[alias] = uri
    new_root = etree.Element(root.tag, attrib=root.attrib, nsmap=nsmap)
    new_root[:] = root[:]
    return new_root.getroottree()

After applying this function, you get a new tree, but you can probably change the tree instance from the single objet from which you access the tree _{... as you have a strong OO design!}.