from collections import defaultdict
s=[('yellow',1),('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]
d=defaultdict(list)
for k, v in s:
  d[k].append(v)
a=sorted(d.items())
print d
print a

'''
defaultdict(<type 'list'>, {'blue': [2, 4], 'red': [1], 'yellow': [1, 3]})
[('blue', [2, 4]), ('red', [1]), ('yellow', [1, 3])]

'''

s = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]
d={}
for k, v in s:
  d.setdefault(k,[]).append(v)
print d
a=sorted(d.items())
print a

'''
{'blue': [2, 4], 'red': [1], 'yellow': [1, 3]}
[('blue', [2, 4]), ('red', [1]), ('yellow', [1, 3])]
'''

s = 'mississippi'
d = defaultdict(int)
for k in s:
  d[k] += 1
print d
a=sorted(d.items())
print a
'''
defaultdict(<type 'int'>, {'i': 4, 'p': 2, 's': 4, 'm': 1})
[('i', 4), ('m', 1), ('p', 2), ('s', 4)]
'''

def constant_factory(value):
  return lambda: value
d = defaultdict(constant_factory('<missing>'))
print d
d.update(name='John', action='ran')
print d
print '%(name)s %(action)s to %(object)s' % d 
'''
defaultdict(<function <lambda> at 0x10c180668>, {})
defaultdict(<function <lambda> at 0x10c180668>, {'action': 'ran', 'name': 'John'})
John ran to <missing>
'''

s = [('red', 1), ('blue', 2), ('red', 3), ('blue', 4), ('red', 1), ('blue', 4)]
d = defaultdict(set)
for k, v in s:
  d[k].add(v)
print d
a=sorted(d.items())
print a
'''
defaultdict(<type 'set'>, {'blue': set([2, 4]), 'red': set([1, 3])})
[('blue', set([2, 4])), ('red', set([1, 3]))]
'''