[FEA] Series transpose

[beckernick]

For pandas API compatibility, we can implement transpose on Series in addition to the existing implementation on DataFrame. As a Series is a 1-D container, in pandas Series.transpose() returns the original Series.

import pandas as pd
​
s = pd.Series([0,1,2])
print(s)
print(s.transpose())
0    0
1    1
2    2
dtype: int64
0    0
1    1
2    2
dtype: int64

This is consistent with numpy semantics for 1-D arrays:

import numpy as np
​
arr = np.arange(5)
np.array_equal(arr, arr.T), arr.__array_interface__["data"] == arr.T.__array_interface__["data"]
(True, True)