题解 | #牛客网用户练习的平均次日留存率#

import pandas as pd 
df = pd.read_csv('nowcoder.csv',sep = ',')
df.date = pd.to_datetime(df.date).dt.date
df1 = df.copy()
df1.date = df.date + pd.Timedelta(days=1)
merge_df = pd.merge(df,df1,how='inner',on=['user_id','date'])
num = merge_df.user_id.count()
total = df.user_id.count()
print(round(num / total,2))