Python 替换一列中的值，具体取决于另一列中的值

如果

col2 value==“b”

如何做到这一点？

---

谢谢，有几种方法可以做到这一点，但为了清楚起见，您可以使用：

为了简单起见，我还修改了

dict

，使其具有整数键

输出：

import pandas as pd

dict = {
    1: 'Alb',
    2: 'Bnk',
    3: 'Cd'
}

df = pd.DataFrame(
    {
        'col1': {
            0: 20,
            1: 2,
            2: 10,
            3: 2,
            4: 44
        }, 
        'col2': {
            0:'a',
            1:'b',
            2:'c',
            3:'b',
            4:20
        }
     }
)

def change(data, col2val, dict):
    if data['col2'] == col2val:
        data['col1'] = dict[data['col1']]

    return data

new_df = df.apply(change, axis = 1, col2val = 'b', dict = dict)

print(new_df)

import pandas as pd

dict = {
    1: 'Alb',
    2: 'Bnk',
    3: 'Cd'
}

df = pd.DataFrame(
    {
        'col1': {
            0: 20,
            1: 2,
            2: 10,
            3: 2,
            4: 44
        }, 
        'col2': {
            0:'a',
            1:'b',
            2:'c',
            3:'b',
            4:20
        }
     }
)

def change(data, col2val, dict):
    if data['col2'] == col2val:
        data['col1'] = dict[data['col1']]

    return data

new_df = df.apply(change, axis = 1, col2val = 'b', dict = dict)

print(new_df)

  col1 col2  
0   20    a  
1  Bnk    b  
2   10    c  
3  Bnk    b  
4   44   20