python - 使用 Pandas 对多个映射列进行按列操作

Question

我有两个数据帧，即 df1 和 df2。我想对 df2 的“New_Amount_Dollar”列执行操作。基本上在 df1 中，我有历史货币数据，我想在给定 df2 中的 Currency 和 Amount_Dollar 的情况下执行按日期计算的操作，以计算 df2 中 New_Amount_Dollar 列的值。

对于“货币”== [AUD, BWP] 我们需要将 Amount_Dollar 乘以相应日期的相应货币值。

对于其他货币，我们需要将 Amount_Dollar 除以相应日期的相应货币值(value)。

例如，在 df2 中，日期 = '01-01-2019' 的第一种货币为 AUD，因此我想计算 New_Amount_Dollar 值，这样

New_Amount_Dollar = Amount_Dollar*来自 df1 的 AUD 值，即 New_Amount_Dollar = 19298*98 = 1891204

另一个例子，在 df2 中我有第三种货币作为 Date = '03-01-2019 的 COP，所以我想计算 New_Amount_Dollar 值，这样

New_Amount_Dollar = Amount_Dollar/来自 df1 的 COP 值，即 New_Amount_Dollar = 5000/0.043 = 116279.06

import pandas as pd
data1 = {'Date':['01-01-2019', '02-01-2019', '03-01-2019', 
                 '04-01-2019','05-01-2019'],
        'AUD':[98, 98.5, 99, 99.5, 97],
        'BWP':[30,31,33,32,31],
        'CAD':[0.02,0.0192,0.0196,0.0196,0.0192],
        'BND':[0.99,0.952,0.970,0.980,0.970],
        'COP':[0.05,0.047,0.043,0.047,0.045]}
df1 = pd.DataFrame(data1)

data2 = {'Date':['01-01-2019', '02-01-2019', '03-01-2019', '04-01-2019','05-01-2019'],
        'Currency':['AUD','AUD','COP','CAD','BND'],
        'Amount_Dollar':[19298, 19210, 5000, 200, 2300],
        'New_Amount_Dollar':[0,0,0,0,0]
        }
df2 = pd.DataFrame(data2) 
print (df2)

df1

         Date   AUD  BWP     CAD    BND    COP
0  01-01-2019  98.0   30  0.0200  0.990  0.050
1  02-01-2019  98.5   31  0.0192  0.952  0.047
2  03-01-2019  99.0   33  0.0196  0.970  0.043
3  04-01-2019  99.5   32  0.0196  0.980  0.047
4  05-01-2019  97.0   31  0.0192  0.970  0.045

df2

         Date Currency  Amount_Dollar  New_Amount_Dollar
0  01-01-2019      AUD          19298                  0
1  02-01-2019      AUD          19210                  0
2  03-01-2019      COP           5000                  0
3  04-01-2019      CAD            200                  0
4  05-01-2019      BND           2300                  0

预期结果

         Date Currency  Amount_Dollar  New_Amount_Dollar
0  01-01-2019      AUD          19298            1891204
1  02-01-2019      AUD          19210          1892185.0
2  03-01-2019      COP           5000          116279.06
3  04-01-2019      CAD            200           10204.08
4  05-01-2019      BND           2300            2371.13

Answer 1

你想要lookup和isin():

# this is to know where to multiply
# where to divide
s = df2['Currency'].isin(['AUD', 'BWP'])

# the values to multiply/divide
m = df1.set_index('Date').lookup(df2['Date'],df2['Currency'])

df2['New_Amount_Dollar'] = df2['Amount_Dollar'] * np.where(s, m, 1/m)

输出:

         Date Currency  Amount_Dollar  New_Amount_Dollar
0  01-01-2019      AUD          19298         1891204.00
1  02-01-2019      AUD          19210         1892185.00
2  03-01-2019      COP           5000          116279.07
3  04-01-2019      CAD            200           10204.08
4  05-01-2019      BND           2300            2371.13