考虑一下:
来源DF:
In [79]: df
Out[79]:
Brains Bodies
0 42 34
1 32 23
选择一列 – 导致Pandas.Series:
In [80]: df['Brains']
Out[80]:
0 42
1 32
Name: Brains, dtype: int64
In [81]: type(df['Brains'])
Out[81]: pandas.core.series.Series
选择DataFrame的子集 – 导致DataFrame:
In [82]: df[['Brains']]
Out[82]:
Brains
0 42
1 32
In [83]: type(df[['Brains']])
Out[83]: pandas.core.frame.DataFrame
结论:第二种方法允许我们从DataFrame中选择多个列.第一个只是选择单列…
演示:
In [84]: df = pd.DataFrame(np.random.rand(5,6), columns=list('abcdef'))
In [85]: df
Out[85]:
a b c d e f
0 0.065196 0.257422 0.273534 0.831993 0.487693 0.660252
1 0.641677 0.462979 0.207757 0.597599 0.117029 0.429324
2