如何在python中获取未过滤的行？

with open('file.txt', 'r') as file:
    lines = file.readlines()
    for line in lines:
        # 对每一行进行处理或过滤
        print(line)

import re

with open('file.txt', 'r') as file:
    lines = file.readlines()
    for line in lines:
        # 使用正则表达式匹配未过滤的行
        if re.match(r'pattern', line):
            print(line)

import pandas as pd

data = pd.read_csv('file.txt', delimiter='\n')
filtered_data = data[data['column_name'].str.contains('pattern')]
print(filtered_data)