Extracting substrings from a string in Python means obtaining a smaller sequence of characters (substring) from a given string. Python provides several methods to achieve this, including slicing, string methods, and regular expressions.
Python extracts a substring from a string
Here are some examples of extracting substrings from a string using different methods in Python:
1. Using Slicing: Slicing involves extracting a portion of the string based on its index positions. The syntax for slicing is string[start_index:end_index], where start_index is the index of the first character to include in the substring, and end_index is the index of the first character not to include in the substring.
# Example string
text = "Hello, World!"
# Extract substring from index 0 to 4 (exclusive)
substring = text[0:5]
print(substring) # Output: "Hello"
2. Using String Methods: Python has built-in string methods that can be used to extract substrings based on specific patterns. Some common methods are split(), find(), startswith(), endswith(), etc.
# Example string
text = "Hello, World!"
# Using split() to extract a substring based on a delimiter (comma in this case)
substring = text.split(',')[0]
print(substring) # Output: "Hello"
# Using find() and slicing to extract a substring between two characters
start_index = text.find('H')
end_index = text.find('!')
substring = text[start_index:end_index+1]
print(substring) # Output: "Hello, World"
3. Using Regular Expressions (Regex): Regular expressions provide a powerful way to extract substrings based on more complex patterns.
import re
# Example string
text = "Hello, World!"
# Using regex to extract all capitalized words
matches = re.findall(r'\b[A-Z][a-z]*\b', text)
print(matches) # Output: ['Hello', 'World']
Output:
These are some of the methods available in Python to extract substrings from a string. The choice of method depends on the specific requirements and patterns present in the string you are working with.
Note: IDE: PyCharm 2021.3.3 (Community Edition)
Windows 10
Python 3.10.1
All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.