How can we extract numbers from a string in Python?

There are several ways to extract the numbers from a string.

1. Regular expressions can be used to match numbers within a string by using the findall function in the re module. For example:

import re

string = "abc123def456"
numbers = re.findall(r'\d+', string)
print(numbers)  # 输出：['123', '456']

1. By using the isdigit() method, you can iterate through each character in a string and determine if it is a digit. For example:

string = "abc123def456"
numbers = ''.join([char for char in string if char.isdigit()])
print(numbers)  # 输出：123456

1. By using the isnumeric() method, similar to isdigit(), it is able to also determine if it contains other numerical characters (such as Chinese numerals). For example:

string = "abc一二三def四五六"
numbers = ''.join([char for char in string if char.isnumeric()])
print(numbers)  # 输出：一二三四五六

Please note that the extracted numbers in the above methods will be returned as strings. If you need to convert them into integers or floating-point numbers, you can use the int() or float() functions for type conversion.