Convert from Camel Case to Snake Case with Regular Expressions in Python

Here's how to convert a string from CamelCase to snake_case in Python with regular expressions.

import re

# Option 1
regex = r'(?<!^)(?=[A-Z])'
re.sub(regex, '_', 'GettingSimple', 0).lower()
# returns 'getting_simple'

# Option 2
pattern = re.compile(r'(?<!^)(?=[A-Z])')
pattern.sub('_', 'nonoMartinezAlonso').lower()
# returns 'nono_martinez_alonso'

See how to Convert from snake_case to camelCase.