熊猫：根据条件为df添加新列

Question

我有df，我需要在其中创建新列。在

i,ID,url,used_at,active_seconds,domain,search_term, diff_time
322015,0120bc30e78ba5582617a9f3d6dfd8ca,vk.com/antoninaribina,2015-10-31 09:16:05,35,vk.com,None, 108    
838267,0120bc30e78ba5582617a9f3d6dfd8ca,vk.com/feed,2015-10-31 09:16:38,54,vk.com,None, 79 
838271,0120bc30e78ba5582617a9f3d6dfd8ca,vk.com/feed?section=photos,2015-11-30 09:17:32,34,vk.com,None, 513   
322026,0120bc30e78ba5582617a9f3d6dfd8ca,vk.com/feed?section=photos&z=photo143297356_397216312%2Ffeed1_143297356_1451504298,2015-11- 30 09:18:06,4,vk.com,None, 242    
838275,0120bc30e78ba5582617a9f3d6dfd8ca,vk.com/feed?section=photos,2015-12-31 09:18:10,4,vk.com,None, 131    
322028,0120bc30e78ba5582617a9f3d6dfd8ca,vk.com/feed?section=comments,2015-12-31 09:18:14,8,vk.com,None, 317  
322029,f85ce4b2f8787d48edc8612b2ccaca83,megarand.ru/contest/121070,2015-12-31 09:18:22,16,megarand.ru,None, 17  
1870917,f85ce4b2f8787d48edc8612b2ccaca83,eldorado.ru/cat/1461428,2015-12-31 09:18:38,6,vk.com,None, 129  
1354612,f85ce4b2f8787d48edc8612b2ccaca83,vk.com/antoninaribina,2015-12-31 19:18:44,56,vk.com,None, 417   

我想添加列period，如果diff_time < 500，period = i，ifdiff_time > 500，period = i + 1和if!=id来自上一个字符串，period = i + 1 期望输出

^{pr2}$

Answer 1

构造一个switch变量，如果需要增加周期，则存储true，否则存储false，然后对获得的序列调用cumsum()函数：

switch = (df.diff_time > 500) | (df.ID != df.ID.shift().fillna(df.ID[0]))
switch.cumsum() + 1

# 0    1
# 1    1
# 2    2
# 3    2
# 4    2
# 5    2
# 6    3
# 7    3
# 8    4
# dtype: int64

将其重新分配给数据帧将满足您的需要：

^{pr2}$