Python的collections模块中的OrderedDict有序字典

d = OrderedDict()
d['a'] = 1
d['b'] = 10
d['c'] = 8
for letter in d:
  print letter

a
b
c

>>> d = OrderedDict(a=1, b=2, c=3)
OrderedDict([('a', 1), ('c', 3), ('b', 2)])

import collections
print 'Regular dictionary:'
d = {}
d['a'] = 'A'
d['b'] = 'B'
d['c'] = 'C'
for k, v in d.items():
  print k, v
print '\nOrderDict:'
d = collections.OrderedDict()
d['a'] = 'A'
d['b'] = 'B'
d['c'] = 'C'
for k, v in d.items():
  print k, v

Regular dictionary:
a A
c C
b B
OrderDict:
a A
b B
c C