计数按用户分组的唯一天数

SELECT user_id, COUNT(DISTINCT activity_date) AS unique_days
FROM user_activity
GROUP BY user_id;

from collections import Counter
import datetime

# 假设你有一个包含用户ID和活动日期的列表
user_activity = [
    {'user_id': 1, 'activity_date': datetime.datetime(2020, 1, 1)},
    {'user_id': 1, 'activity_date': datetime.datetime(2020, 1, 2)},
    {'user_id': 2, 'activity_date': datetime.datetime(2020, 1, 1)},
]

# 使用Counter来计算按用户分组的唯一天数
unique_days = Counter()

for activity in user_activity:
    user_id = activity['user_id']
    activity_date = activity['activity_date'].date()
    unique_days[(user_id, activity_date)] += 1

# 输出按用户分组的唯一天数
for user_id, count in unique_days.items():
    print(f"User {user_id}: {count} unique days")