Pandas使用数组分配列值

import pandas as pd

data = {'A': [1, 2, 3, 4],
        'B': [5, 6, 7, 8]}
df = pd.DataFrame(data)

df['C'] = [9, 10, 11, 12]  # 为df添加一列C，并赋予相应的值

import pandas as pd

data = {'A': [1, 2, 3, 4],
        'B': [5, 6, 7, 8]}
df = pd.DataFrame(data)

df.loc[df['A'] > 2, 'C'] = 100  # 当'A'列的值大于2时，为'C'列赋值为100

import pandas as pd

data = {'A': [1, 2, 3, 4],
        'B': [5, 6, 7, 8]}
df = pd.DataFrame(data)

def assign_value(x):
    if x > 2:
        return 100
    else:
        return 200

df['C'] = df['A'].apply(assign_value)  # 根据自定义函数assign_value的返回值为'A'列赋值为相应的值