5.7.12. API-index¶

结构:

Index(data=None, dtype=None, copy=False, name=None, tupleize_cols=True, **kwargs)
参数:
data: array-like (1-dimensional)
dtype: NumPy dtype (default: object)
copy: bool
name: object
tupleize_cols: bool (default: True)

说明:

Immutable sequence used for indexing and alignment.
The basic object storing axis labels for all pandas objects.

实例:

In [57]: s4 = pd.Series(np.array([1,1,2,3,5,8]))
    ...: print(s4.index)
RangeIndex(start=0, stop=6, step=1)

// 设定一个自定义的索引值
In [59]: s4.index = ['a','b','c','d','e','f']
    ...: print(s4.index)
    ...:
Index(['a', 'b', 'c', 'd', 'e', 'f'], dtype='object')

索引值的使用:
在一维数组中，就无法通过索引标签获取数据，这也是序列不同于一维数组的一个方面
print('s4[3]: ',s4[3])
print('s4[e]: ',s4['e'])
print("s4[1,3,5]: ",s4[[1,3,5]])
print("s4[['a','b','d','f']]: ",s4[['a','b','d','f']])
print('s4[:4]: ',s4[:4])
print("s4['c':]: ",s4['c':])
print("s4['b':'e']: ",s4['b':'e'])

// 打印:
s4[3]:  3
s4[e]:  5
s4[1,3,5]:  b    1
d    3
f    8
dtype: int64
s4[['a','b','d','f']]:  a    1
b    1
d    3
f    8
dtype: int64
s4[:4]:  a    1
b    1
c    2
d    3
dtype: int64
s4['c':]:  c    2
d    3
e    5
f    8
dtype: int64
s4['b':'e']:  b    1
c    2
d    3
e    5
dtype: int64