我在 Jupyter 笔记本中创建 DataFrame 对象:
data = {'state':['Ohio','Ohio','Ohio','Nevada','Nevada'],
'year':[2000, 2001, 2002, 2000, 2001],
'pop':[1.5, 2.0, 3.6, 2.4, 2.9]}
frame = DataFrame(data)
当我提取“年份”列时,没问题:
In [30]: frame.year
Out[30]: 0 2000
1 2001
2 2002
3 2000
4 2001
Name: year, dtype: int64
但是当我提取列“pop”(frame.pop)时,结果是:
Out[31]:
<bound method NDFrame.pop of pop state year
0 1.5 Ohio 2000
1 2.0 Ohio 2001
2 3.6 Ohio 2002
3 2.4 Nevada 2000
4 2.9 Nevada 2001>
为什么结果与“frame.year”的结果不同?