Python Lxml - Append a existing xml with new data

I am new to python/lxml After reading the lxml site and dive into python I could not find the solution to my n00b troubles.开发者_Go百科 I have the below xml sample:

---------------
<addressbook>
    <person>
        <name>Eric Idle</name>
        <phone type='fix'>999-999-999</phone>
        <phone type='mobile'>555-555-555</phone>
        <address>
            <street>12, spam road</street>
            <city>London</city>
            <zip>H4B 1X3</zip>
        </address>
    </person>
</addressbook>
-------------------------------

I am trying to append one child to the root element and write the entire file back out as a new xml or over write the existing xml. Currently all I am writing is one line.

from lxml import etree
tree = etree.parse('addressbook.xml')
root = tree.getroot()
oSetroot = etree.Element(root.tag)
NewSub = etree.SubElement ( oSetroot, 'CREATE_NEW_SUB' )
doc = etree.ElementTree (oSetroot)
doc.write ( 'addressbook1.xml' )

TIA

---

You could make a new tree by copying over all of the old one (not just the root tag!-), but it's much simpler to edit the existing tree in-place (and, why not?-)...:

tree = etree.parse('addressbook.xml')
root = tree.getroot()
NewSub = etree.SubElement ( root, 'CREATE_NEW_SUB' )
tree.write ( 'addressbook1.xml' )

which puts in addressbook1.xml:

<addressbook>
    <person>
        <name>Eric Idle</name>
        <phone type="fix">999-999-999</phone>
        <phone type="mobile">555-555-555</phone>
        <address>
            <street>12, spam road</street>
            <city>London</city>
            <zip>H4B 1X3</zip>
        </address>
    </person>
<CREATE_NEW_SUB /></addressbook>

(which I hope is the effect you're looking for...?-)