尝试通过标头获取数据帧列时发生TypeError

Question

我已将sklearn中的一个内置数据集加载到熊猫数据框架中。 我想从一个列中提取数据，正如该列的标题所指定的那样。 然而，这会产生一个类型错误，我不知道为什么。 下面是MWE，任何帮助都将不胜感激

import pandas as pd
from sklearn.datasets import load_breast_cancer
meh = load_breast_cancer()

X = pd.DataFrame(meh.data, columns=[meh.feature_names])

# Prints nice dataframe
print(X)  

# TypeError: only integer scalar arrays can be converted to a scalar index
print(X["mean radius"])

Answer 1

问题是您使用传递嵌套列表创建了MultiIndex，因此只需要删除[]：

X = pd.DataFrame(meh.data, columns=meh.feature_names)

print(X.columns)
Index(['mean radius', 'mean texture', 'mean perimeter', 'mean area',
       'mean smoothness', 'mean compactness', 'mean concavity',
       'mean concave points', 'mean symmetry', 'mean fractal dimension',
       'radius error', 'texture error', 'perimeter error', 'area error',
       'smoothness error', 'compactness error', 'concavity error',
       'concave points error', 'symmetry error', 'fractal dimension error',
       'worst radius', 'worst texture', 'worst perimeter', 'worst area',
       'worst smoothness', 'worst compactness', 'worst concavity',
       'worst concave points', 'worst symmetry', 'worst fractal dimension'],
      dtype='object')

详细信息：

X = pd.DataFrame(meh.data, columns=[meh.feature_names])
print(X.columns)

MultiIndex([(            'mean radius',),
            (           'mean texture',),
            (         'mean perimeter',),
            (              'mean area',),
            (        'mean smoothness',),
            (       'mean compactness',),
            (         'mean concavity',),
            (    'mean concave points',),
            (          'mean symmetry',),
            ( 'mean fractal dimension',),
            (           'radius error',),
            (          'texture error',),
            (        'perimeter error',),
            (             'area error',),
            (       'smoothness error',),
            (      'compactness error',),
            (        'concavity error',),
            (   'concave points error',),
            (         'symmetry error',),
            ('fractal dimension error',),
            (           'worst radius',),
            (          'worst texture',),
            (        'worst perimeter',),
            (             'worst area',),
            (       'worst smoothness',),
            (      'worst compactness',),
            (        'worst concavity',),
            (   'worst concave points',),
            (         'worst symmetry',),
            ('worst fractal dimension',)],
           )