在将系列映射到数据帧时,避免使用SettWithCopy警告

映射pandas系列时 s 到数据帧 x ,我收到SettingsWithCopy警告:

s.head()
84     2013-06-05 10:20:29
87     2013-06-05 15:27:56
469    2013-06-28 03:20:05
4670   2013-11-15 11:10:48
4673   2013-11-15 14:08:01
Name: timestamp, dtype: datetime64[ns]

y.head()
min max
0   2013-06-02 09:10:51 2013-06-02 10:27:44
1   2013-06-12 03:08:35 2013-06-12 03:08:35
2   2013-08-03 09:11:35 2021-01-26 23:05:17

x.head()
timestamp
4   2013-06-01 04:12:34
5   2013-06-01 04:19:08
6   2013-06-01 05:18:35
7   2013-06-01 06:00:19
8   2013-06-01 09:16:13

dfo = x.assign(a=1).merge(y.assign(a=1), on='a') 
s = df.loc[(dfo['min']<=dfo['timestamp']) & (dfo['max']>=dfo['timestamp']), 'timestamp']

x['count']=x['timestamp'].map(s.value_counts()).fillna(0).astype(int)

<ipython-input-205-91489a4af264>:1: SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead

由于我正在基于序列图创建一个新列,为什么会抛出错误(复制的切片是什么?),以及用什么正确的方法重写它 i.loc 因为我没有使用索引器?