对数据框熊猫的列中存在的列表执行计算

Question

I have the below dataframe:

    Position        A           B   
0   29644164       71.0    [31, 38, 1, 1]   
1   45861974       45.0    [17, 26, 1, 1]   
2   58142396       69.0    [37, 31, 0, 1]   
3   41223046       75.0    [21, 53, 0, 1] 

I'd like to do calculations on column B. I'd like to sum the 2 numbers in 2 last positions, and divide them with the sum of all 4 numbers. Then, add the results to a new column 'calc'

So the dataframe I'm expecting will be:

     Position        A           B          calc
0   29644164       71.0    [3, 5, 1, 1]     0.2
1   45861974       45.0    [2, 2, 1, 1]     0.333
2   58142396       69.0    [3, 7, 0, 1]     0.1
3   41223046       75.0    [3, 2, 0, 1]     0.2

How can I do it?

Answer 1

Use list comprehension:

df['calc'] = [sum(x[-2:]) / sum(x) for x in df.B]
print (df)
   Position     A               B      calc
0  29644164  71.0  [31, 38, 1, 1]  0.028169
1  45861974  45.0  [17, 26, 1, 1]  0.044444
2  58142396  69.0  [37, 31, 0, 1]  0.014493
3  41223046  75.0  [21, 53, 0, 1]  0.013333

Details :

print ([sum(x[-2:]) for x in df.B])
[2, 2, 1, 1]

print ([sum(x) for x in df.B])
[71, 45, 69, 75]