numpy中提供了那种类型的对象
A. Series
B. ndarray
C. DataFrame
D. asarray
df1=pd.DataFrame([[5,2,3],[4,5,6],[7,8,9]], index=['A','B','D'], columns=['C1','C2','C3']), 其中df1.loc['A']['C2']的值为
A. 2
B. 5
C. 3
D. 7
a=numpy.array([[5,2,3],[4,5,6],[7,8,9]]),其中a[2:,0:-1]的值为
A. array([[4, 5],[7, 8]])
B. array([[7, 8, 9]])
C. array([[7, 8]])
D. 报错
df1=pd.DataFrame([[5,2,3],[4,5,6],[7,8,9]], columns=['C1','C2','C3']), 其中df1.iloc[2][1]的值为
A. 8
B. 7
C17C28C39Name: 2, dtype: int64
D. 报错