如何在panda中将数据帧的一列值复制到其他数据帧的另一列

Question

在将字符串列的值一个接一个地复制到另一个数据帧的列时，我得到了一个包含方括号的输出：

chk.at[index,'StartLocation1'] = chkn['StartLocation1'].values
chk.at[index,'EndLocation1'] = chkn['EndLocation1'].values
0        [Petrol Pump-Ramji Ambedkar Nagar]
1                           [V Enterprises]
2                                   [Baola]
3                         [Dharmajyot-Vapi]
4    [KINGSTON TOWER VASAI Dominos-(THANE)]
Name: StartLocation1, dtype: object

因此，我进一步考虑删除这个[]括号：我已经应用了这个：

chk['EndLocation1'].str.strip('[]').astype(str)
0      nan
1      nan
2      nan
3      nan
4      nan

但是，我有nan的价值观。请支持！

看看这是我的全部代码：

chk['StartLocation1'] = ''
chk['EndLocation1'] = ''
for index, row in chk.iterrows():
start = row.StartTime
end = row.EndTime
reg = row.RegistrationNo
query = "SELECT TOP 1 RegistrationNo, GPSDateTime, Location  FROM GPSEventsDataCurrentWeek where GPSDateTime Between 'start_date' and 'end_date' and RegistrationNo = 'reg' and GroundSpeed > 0 ORDER BY GPSDateTime ASC"
query = query.replace('start_date', start.strftime('%m/%d/%Y %H:%M:%S'))
query = query.replace('end_date', end.strftime('%m/%d/%Y %H:%M:%S'))
query = query.replace('reg', str(reg))
chk1 = pd.read_sql(query, con=engine)

chk1 = chk1.rename({'Location': 'StartLocation1','GPSDateTime': 'StartTime'}, axis=1)

query2 = "SELECT TOP 1 RegistrationNo, GPSDateTime, Location  FROM GPSEventsDataCurrentWeek where GPSDateTime Between 'start_date' and 'end_date' and RegistrationNo = 'reg' and GroundSpeed > 0 ORDER BY GPSDateTime DESC"
query2 = query2.replace('start_date', start.strftime('%m/%d/%Y %H:%M:%S'))
query2 = query2.replace('end_date', end.strftime('%m/%d/%Y %H:%M:%S'))
query2 = query2.replace('reg', str(reg))
chk2 = pd.read_sql(query2, con=engine)

chk2 = chk2.rename({'Location': 'EndLocation1','GPSDateTime': 'EndTime'}, axis=1)

chkn = pd.merge(chk1,chk2, on = ['RegistrationNo'], how = 'outer')
print(chkn[['StartLocation1','EndLocation1']])

chk.at['StartLocation1'] = chkn['StartLocation1'].values
chk.at[index,'EndLocation1'] = chkn['EndLocation1'].values

这是我的数据帧chk:

Companyid   RegistrationNo  Date    Hour    Value   RunningDuration StartTime   EndTime
0   236.0   MH-01-CJ-3571   2020-09-01  0.0 True    00:42:00    2020-09-01 00:08:00 2020-09-01 00:59:00
1   236.0   MH-01-CV-7460   2020-09-01  0.0 True    00:49:00    2020-09-01 00:09:00 2020-09-01 00:58:00
2   654.0   MH-04-JK-4102   2020-09-01  0.0 True    00:03:00    2020-09-01 00:11:00 2020-09-01 00:24:00
3   654.0   DN-09-R-9421    2020-09-01  0.0 True    00:02:00    2020-09-01 00:24:00 2020-09-01 00:54:00
4   236.0   MH-01-CV-7456   2020-09-01  0.0 True    00:04:00    2020-09-01 00:38:00 2020-09-01 00:42:00

Answer 1

也许一个可能的解决方案是通过列表元素的联接(python中的列表联接列表(来选择列表中的唯一值。df.values返回一个n数组对象，因此返回的值是一个长度为1的列表，但建议使用df.to_numpy(https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.values.html)

无论如何，我认为以这种方式分配列并不是最好的方法