etree Clone Node

How to clone Element objects in Python xml.etree? I'm trying to procedurally move and 开发者_Python百科copy (then modify their attributes) nodes.

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You can just use copy.deepcopy() to make a copy of the element. (this will also work with lxml by the way).

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A different, and somewhat disturbing solution:

new_element = lxml.etree.fromstring(lxml.etree.tostring(elem))

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If you have a handle on the Element elem's parent you can call

new_element = SubElement(parent, elem.tag, elem.attrib)

Otherwise you might want to try

new_element = makeelement(elem.tag, elem.attrib)

but this is not advised.

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At least in Python 2.7 etree Element has a copy method: http://hg.python.org/cpython/file/2.7/Lib/xml/etree/ElementTree.py#l233

It is a shallow copy, but that is preferable in some cases.

In my case I am duplicating some SVG Elements and adding a transform. Duplicating children wouldn't serve any purpose since where relevant they already inherit their parent's transform.

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If you procedurally move through your tree with loops, you can use insert to clone directly ( insert(index, subelement) ) and tree indexing (both in the documentation):

import xml.etree.ElementTree as ET
mytree = ET.parse('some_xml_file.xml')  # parse tree from xml file
root = mytree.getroot()  # get the tree root
    
for elem in root:  # iterate over children of root
   if condition_for_cloning(elem) == True:      
      elem.insert(len(elem), elem[3])  # insert the 4th child of elem to the end of the element (clone an element)  

or for children with some tag:

for elem in root:
   children_of_interest = elem.findall("tag_of_element_to_clone")
   elem.insert(len(elem), children_of_interest[1])

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For anyone visiting from the future:

If you want to clone the entire element, use append.

new_tree = ET.Element('root')
for elem in a_different_tree:
    new_tree.append(elem)

@dennis-williamson made a comment about it which I overlooked and eventually stumbled on the answer here https://stackoverflow.com/a/6533808/4916945

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For future reference.

Simplest way to copy a node (or tree) and keep it's children, without having to import ANOTHER library ONLY for that:

def copy_tree( tree_root ):
    return et.ElementTree( tree_root );

duplicated_node_tree = copy_tree ( node );    # type(duplicated_node_tree) is ElementTree
duplicated_tree_root_element = new_tree.getroot();  # type(duplicated_tree_root_element) is Element