如何將數據幀的一列的值復制到熊貓中其他數據幀的另一列？

Question

在將字符串列的值一一復制到另一個數據框的列時，我將其作為包含方括號的輸出：

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

所以我想刪除這個 [] 括號：我已經應用了這個：

chk['EndLocation1'].str.strip('[]').astype(str)

0      nan
1      nan
2      nan
3      nan
4      nan

但是，我有 nan 值。 請支持！

看到這是我的全部代碼：

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

這是我的數據框 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

也許一個可能的解決方案是通過列表元素的連接選擇列表中的唯一值（ python 中的列表連接列表）。 df.values 返回一個 n 數組對象，因此返回的值是一個長度為 1 的列表，但建議使用 df.to_numpy 代替（ https://pandas.pydata.org/pandas-docs/stable/reference/api/ pandas.DataFrame.values.html )

無論如何，我認為以這種方式分配列並不是最好的方法。