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Pandas对一列做运算

可以用apply

In [95]: df = pd.DataFrame(data = [[1,2,3,4],[5,6,7,8,]], columns=['a','b','c','
    ...: d'])                                                                   

In [96]: df                                                                     
Out[96]: 
   a  b  c  d
0  1  2  3  4
1  5  6  7  8

In [97]: df['a'] = 1/df['a']                                                    

In [98]: df                                                                     
Out[98]: 
     a  b  c  d
0  1.0  2  3  4
1  0.2  6  7  8

In [99]: df['b'] = df['b'] * 2                                                  

In [100]: df['b']                                                               
Out[100]: 
0     4
1    12
Name: b, dtype: int64

In [101]: df                                                                    
Out[101]: 
     a   b  c  d
0  1.0   4  3  4
1  0.2  12  7  8

In [102]: df['c'] = df['c']*10 + 1                                              

In [103]: df                                                                    
Out[103]: 
     a   b   c  d
0  1.0   4  31  4
1  0.2  12  71  8

In [107]: def foo(x, y): 
     ...:     if x == 8: 
     ...:         return x 
     ...:     return x*y + 1 
     ...:                                                                       

In [108]: df['d'] = df['d'].apply(foo, args=(10,))                              

In [109]: df                                                                    
Out[109]: 
     a   b   c   d
0  1.0   4  31  41
1  0.2  12  71   8