如何在python中仅从txt文件中提取第一个和最后一个数值？

import re

def extract_first_and_last_number(file_path):
    with open(file_path, 'r') as file:
        content = file.read()
    
    # 使用正则表达式查找所有的数值
    numbers = re.findall(r'-?\d+\.?\d*', content)
    
    if numbers:
        first_number = float(numbers[0])
        last_number = float(numbers[-1])
        return first_number, last_number
    else:
        return None, None

file_path = 'example.txt'
first_number, last_number = extract_first_and_last_number(file_path)

if first_number is not None and last_number is not None:
    print(f'第一个数值: {first_number}')
    print(f'最后一个数值: {last_number}')
else:
    print('未找到数值')

这是一个示例文件，包含一些数值：10, 20.5, 30, 40.75。