把正方形矩阵，比如相关系数矩阵，转化为3列以便做网络图

# -*- coding:utf-8 -*-
import pandas as pd
import numpy as np

data=pd.read_excel('D:\\simil.xlsx')
print data.head()

###索引变成列
#dd.reset_index(inplace=True)

####列转行
bfm=pd.melt(data,id_vars=['index'])
bfm.to_csv('D:\\bfm.csv')