题解 | #牛客网用户练习的平均次日留存率#

import pandas as pd
from datetime import timedelta
data = pd.read_csv('nowcoder.csv')
data['date'] = pd.to_datetime(data['date']).dt.date
data.drop_duplicates(subset=['user_id','date'],inplace = True)
new_nowcoder = pd.merge(data, data, on='user_id',how='inner', suffixes=['_a','_b'])
new_nowcoder['diff']=new_nowcoder['date_b']-new_nowcoder['date_a']
result = new_nowcoder[new_nowcoder['diff']==timedelta(days=1)]['diff'].count()/new_nowcoder[new_nowcoder['diff']==timedelta(days=0)]['diff'].count()
print(round(result,2))