pandas set_index和reset_index的用法

1.set_index

DataFrame能夠經過set_index方法，能夠設置單索引和複合索引。 
DataFrame.set_index(keys, drop=True, append=False, inplace=False, verify_integrity=False) 
append添加新索引，drop爲False，inplace爲True時，索引將會還原爲列

In [307]: data
Out[307]: 
     a    b  c    d
0  bar  one  z  1.0
1  bar  two  y  2.0
2  foo  one  x  3.0
3  foo  two  w  4.0
 
In [308]: indexed1 = data.set_index('c')
 
In [309]: indexed1
Out[309]: 
     a    b    d
c               
z  bar  one  1.0
y  bar  two  2.0
x  foo  one  3.0
w  foo  two  4.0
 
In [310]: indexed2 = data.set_index(['a', 'b'])
 
In [311]: indexed2
Out[311]: 
         c    d
a   b          
bar one  z  1.0
    two  y  2.0
foo one  x  3.0
    two  w  4.0

　　

2.reset_index

reset_index能夠還原索引，重新變爲默認的整型索引 
DataFrame.reset_index(level=None, drop=False, inplace=False, col_level=0, col_fill=」) 
level控制了具體要還原的那個等級的索引 
drop爲False則索引列會被還原爲普通列，不然會丟失

In [318]: data
Out[318]: 
         c    d
a   b          
bar one  z  1.0
    two  y  2.0
foo one  x  3.0
    two  w  4.0
 
In [319]: data.reset_index()
Out[319]: 
     a    b  c    d
0  bar  one  z  1.0
1  bar  two  y  2.0
2  foo  one  x  3.0
3  foo  two  w  4.0

　

轉自：https://blog.csdn.net/jingyi130705008/article/details/78162758