df.melt(),df.pivot() 互为逆转函数

In [23]:

df=pd.DataFrame({'A':['a','b','c'],

                'B':[1,3,5],

                'C':[2,4,6]})

    In [24]:  df     Out[24]:

	A	B	C
0	a	1	2
1	b	3	4
2	c	5	6

In [29]:

melted=df.melt('A')

melted

Out[29]:

	A	variable	value
0	a	B	1
1	b	B	3
2	c	B	5
3	a	C	2
4	b	C	4
5	c	C	6

In [32]:

reshaped=melted.pivot(index='A',columns='variable')

reshaped

    Out[32]:

	value
variable	B	C
A
a	1	2
b	3	4
c	5	6

In [33]:

reshaped.reset_index()

    Out[33]:

	A	value
variable		B	C
0	a	1	2
1	b	3	4
2	c	5	6