Python按年显示多行

from datetime import datetime
from collections import defaultdict

# 示例数据
dates = [
    datetime(2022, 1, 15),
    datetime(2023, 3, 22),
    datetime(2022, 5, 7),
    datetime(2023, 8, 11),
    datetime(2021, 11, 30)
]

# 按年分组
grouped_by_year = defaultdict(list)
for date in dates:
    grouped_by_year[date.year].append(date)

# 显示结果
for year, dates_in_year in grouped_by_year.items():
    print(f"Year {year}:")
    for date in dates_in_year:
        print(f"  {date.strftime('%Y-%m-%d')}")

import re

def is_valid_date(date_str):
    pattern = re.compile(r'^\d{4}-\d{2}-\d{2}$')
    return bool(pattern.match(date_str))

# 示例
date_str = "2022-13-01"  # 无效日期
if is_valid_date(date_str):
    date_obj = datetime.strptime(date_str, '%Y-%m-%d')
else:
    print("Invalid date format!")