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Python Time & Space Complexity

Xml

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')