python: dictionary (4)

Abstract: implement nested dictionary to store data frame as in R

The script:
# -*- coding: utf-8 -*-
"""
Created on Sat Aug  1 17:57:36 2015

@author: yuan
"""
import numpy as np
import pandas as pd

#create a data frame like in R
l=range(12)
df=np.array(l).reshape((3,4))
df=pd.DataFrame(df,columns=['a','b','c','d'], index=['a1','a2','a3'])
print df

#convert df to dictionary
d={}
for row_index,row in df.iterrows():
    d[row_index]=row
    for col_name in df.columns:
        print row_index, col_name, row[col_name]
       
print 'Nested dictionary:', d
print 'rowname:a2, colname:c =', d['a2']['c']

print 'convert dictionary to df:'
print pd.DataFrame(d)