ordereddict python

from collections import OrderedDict

# Remembers the order the keys are added!
x = OrderedDict(a=1, b=2, c=3)

from collections import OrderedDict 
od = OrderedDict()

An OrderedDict is a dictionary subclass that remembers the order 
that keys were first inserted. A regular dict doesn’t track the 
insertion order, and iterating it gives the values in an arbitrary 
order.
# A Python program to demonstrate working of OrderedDict 
from collections import OrderedDict 
d = {} # regular dict
d['a'] = 1
d['b'] = 2
d['c'] = 3
for key, value in d.items(): 
    print(key, value) 
# Output
# ('a', 1)
# ('c', 3)
# ('b', 2)  
od = OrderedDict() # Ordered Dict
od['a'] = 1
od['b'] = 2
od['c'] = 3
for key, value in od.items(): 
    print(key, value) 
# Output
# ('a', 1)
# ('b', 2)
# ('c', 3)

>>> # regular unsorted dictionary
>>> d = {'banana': 3, 'apple': 4, 'pear': 1, 'orange': 2}

>>> # dictionary sorted by key
>>> OrderedDict(sorted(d.items(), key=lambda t: t[0]))
OrderedDict([('apple', 4), ('banana', 3), ('orange', 2), ('pear', 1)])

>>> # dictionary sorted by value
>>> OrderedDict(sorted(d.items(), key=lambda t: t[1]))
OrderedDict([('pear', 1), ('orange', 2), ('banana', 3), ('apple', 4)])

>>> # dictionary sorted by length of the key string
>>> OrderedDict(sorted(d.items(), key=lambda t: len(t[0])))
OrderedDict([('pear', 1), ('apple', 4), ('orange', 2), ('banana', 3)])

import collections

print 'Regular dictionary:'
d = {}
d['a'] = 'A'
d['b'] = 'B'
d['c'] = 'C'
d['d'] = 'D'
d['e'] = 'E'

for k, v in d.items():
    print k, v

print '\nOrderedDict:'
d = collections.OrderedDict()
d['a'] = 'A'
d['b'] = 'B'
d['c'] = 'C'
d['d'] = 'D'
d['e'] = 'E'

for k, v in d.items():
    print k, v