数据帧，从列表中设置索引

Question

从列表中创建数据帧时可以将索引设置为其中一个值吗？

import pandas as pd 

tmp = [['a', 'a1'], ['b',' b1']] 

df = pd.DataFrame(tmp, columns=["First", "Second"]) 

     First Second 
0   a a1 
1   b b1 

，我想怎么看：

 First Second 
a   a a1 
b   b b1 

Answer 1

>>> pd.DataFrame(tmp, columns=["First", "Second"]).set_index('First', drop=False) 
     First Second 
First    
a   a  a1 
b   b  b1 

Answer 2

如果你不希望指数名称：

df = pd.DataFrame(tmp, columns=["First", "Second"], index=[i[0] for i in tmp]) 

结果：

First Second 
a  a  a1 
b  b  b1