要解决此问题，您需要执行以下操作：
1.按用户分组，然后按日期排序。
1.检查横幅显示或横幅单击事件是否在每个用户的订单事件之前。
1.对满足条件的用户进行计数。
下面是这个问题的答案：

# Grouping by user and sorting by date
grouped = df.groupby('user').apply(lambda x: x.sort_values('date'))

# Check for each user if they have a banner_show or banner_click event before an order
def check_order_after_banner(user_df):
    banner_show_indices = user_df[user_df['title'] == 'banner_show'].index.tolist()
    banner_click_indices = user_df[user_df['title'] == 'banner_click'].index.tolist()
    order_indices = user_df[user_df['title'] == 'order'].index.tolist()
    for order_index in order_indices:
        if any(banner_index < order_index for banner_index in banner_show_indices) or \
           any(banner_index < order_index for banner_index in banner_click_indices):
            return True
    return False
users_with_condition = grouped.groupby('user').apply(check_order_after_banner)
count_users = sum(users_with_condition)
print(count_users)

要实现这一点，您可以按用户对您的框架进行分组，然后按日期排序。之后，对于每个用户，您可以检查在订单事件之前是否有banner_show或banner_click事件。这里有一个解决方案：

# Grouping by user and sorting by date
grouped = df.groupby('user').apply(lambda x: x.sort_values('date'))
# Check for each user if they have a banner_show or banner_click event before an order
def check_order_after_banner(user_df):
    banner_show_indices = user_df[user_df['title'] == 'banner_show'].index.tolist()
    banner_click_indices = user_df[user_df['title'] == 'banner_click'].index.tolist()
    order_indices = user_df[user_df['title'] == 'order'].index.tolist()
    
    for order_index in order_indices:
        if any(banner_index < order_index for banner_index in banner_show_indices) or \
           any(banner_index < order_index for banner_index in banner_click_indices):
            return True
    return False

users_with_condition = grouped.groupby('user').apply(check_order_after_banner)
count_users = sum(users_with_condition)

print(count_users)

此解决方案将为您提供在查看或单击横幅后下订单的用户计数。

我会用途：

# ensure data is sorted by date
df = df.sort_values(by=['user', 'time'])

# flag rows after the banner was seen/clicked
banner_seen = (df['title'].str.startswith('banner')
               .groupby(df['user']).cummax()
              )

N = df.loc[df['title'].eq('order') & banner_seen, 'user'].nunique()

输出：2
中间体：

user         title                 time  banner_seen  order  order_after_banner
0  user_0  banner_click  2017-02-09 20:24:04         True  False               False
1  user_0         order  2017-03-20 19:24:04         True   True                True
3  user_1         order  2017-02-04 20:24:04        False   True               False
2  user_1   banner_show  2017-04-14 20:24:04         True  False               False
5  user_2         order  2017-03-12 20:24:04        False   True               False
5  user_2  banner_click  2017-08-11 20:24:04         True  False               False
4  user_2         order  2017-08-12 20:24:04         True   True                True

要获取每个用户在看到横幅后的订单计数，请执行以下操作：

(df['title'].eq('order') & banner_seen).groupby(df['user']).sum()

输出量：

user
user_0    1
user_1    0
user_2    1
Name: title, dtype: int64