输出的相关矩阵转换为一列

我的问题很简单 就是如何将输出的相关矩阵

变成下列形式

代码附上 求修改
import numpy as np
import pandas as pd
df = pd.read_csv(r'C:\Users\wxy\Desktop\re\444.csv')
a=df.corr()
print(a)

类似于这样操作，参考一下：

import pandas as pd 

df=pd.DataFrame({"1":[0.3524,-0.3124,0.2257,-0.1214],"2":[0.6214,0.3217,-0.2111,-0.2389],"3":[0.0124,-0.01478,0.2013,0.1624],"4":[0.3333,0.2222,0.1111,-0.2131]},index=range(1,5))
print(df)
df0=[]
for x in df.index:
    df0.append(df.loc[x,:])
d=pd.concat(df0,keys=df.index)

print(d)

1  1    0.35240
   2    0.62140
   3    0.01240
   4    0.33330
2  1   -0.31240
   2    0.32170
   3   -0.01478
   4    0.22220
3  1    0.22570
   2   -0.21110
   3    0.20130
   4    0.11110
4  1   -0.12140
   2   -0.23890
   3    0.16240
   4   -0.21310