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xml Module¶
The xml module provides base functionality for parsing and manipulating XML documents, with submodules for DOM, SAX, and ElementTree.
Complexity Reference¶
| Operation | Time | Space | Notes |
|---|---|---|---|
| Parse XML | O(n) | O(n) | n = document size; DOM loads entire tree |
| DOM traversal | O(n) | O(n) | n = nodes; consider SAX for large files |
| XPath query | O(n) | O(n) | n = nodes searched; result depends on query |
XML Processing¶
Using ElementTree¶
import xml.etree.ElementTree as ET
# Parse XML - O(n)
tree = ET.parse('data.xml')
root = tree.getroot()
# Navigate tree - O(n)
for item in root.findall('item'):
name = item.find('name').text
price = item.find('price').text
print(f"{name}: {price}")
# Modify and save - O(n)
root.attrib['updated'] = 'True'
tree.write('modified.xml')
Creating XML¶
import xml.etree.ElementTree as ET
# Create root - O(1)
root = ET.Element('catalog')
# Add children - O(1) each
item = ET.SubElement(root, 'item')
item.set('id', '1')
name = ET.SubElement(item, 'name')
name.text = 'Product'
price = ET.SubElement(item, 'price')
price.text = '29.99'
# Save - O(n)
tree = ET.ElementTree(root)
tree.write('output.xml')