Lxml. etree tutorial 6: Tree Iteration

Elements provide a tree iterator for this purpose. It yields elements in document order, I. e. in the order their tags wowould appear if you serialised the tree to XML:

 
>>> Root = etree. element ("root") >>> etree. subelement (root, "child "). TEXT = "CHILD 1" >>> etree. subelement (root, "child "). TEXT = "Child 2" >>> etree. subelement (root, "another "). TEXT = "child 3" >>> print (etree. tostring (root, pretty_print = true )) <root> <child> Child 1 </child> <child> Child 2 </child> <another> child 3 </Another> </root> for element in root. ITER ():... print ("% s-% s" % (element. tag, element. text) Root-nonechild-Child 1 child-Child 2 Another-child 3
 

If you know you are only interested in a single tag, you can pass its name to ITER () to have it filter for you. starting with lxml 3.0, you can also pass more than one tag to intercept on multiple tags during iteration.

 
>>> For element in root. ITER ("child "):... print ("% s-% s" % (element. tag, element. text) Child-Child 1 child-Child 2 >>> for element in root. ITER ("another", "child "):... print ("% s-% s" % (element. tag, element. text) Child-Child 1 child-Child 2 Another-child 3
 

By default, iteration yields all nodes in the tree, including processinginstructions, comments and entity instances. if you want to make sure only element objects are returned, you can pass the element factory as tag parameter:

>>> Root. append (etree. entity ("#234") >>> root. append (etree. comment ("some comment") >>> for element in root. ITER ():... if isinstance (element. tag, basestring ):... print ("% s-% s" % (element. tag, element. text ))... else :... print ("Special: % s-% s" % (element, element. text) Root-nonechild-Child 1 child-Child 2 Another-child 3 Special: Your-specific special: <! -- Some comment -->-some comment >>> for element in root. ITER (TAG = etree. element ):... print ("% s-% s" % (element. tag, element. text) Root-nonechild-Child 1 child-Child 2 Another-child 3 >>> for element in root. ITER (TAG = etree. entity ):... print (element. text) plaintext
 

Note that passing a wildcard "*" tag name will also yield all element nodes (and only elements ).

In lxml. etree, elements provide further iterators for all directions ctions in the tree: children, parents (or rather ancestors) and siblings.