遍历字典

d = {'x': 1, 'y': 2, 'z': 3}

遍历keys

for key in d:
    print key,

y x z

for key in d.iterkeys():
    # d.iterkeys(): an iterator over the keys of d
    print key,

y x z

for key in d.keys():
    # d.keys() -> ['y', 'x', 'z']
    print key,

y x z

遍历values

for value in d.itervalues():
    # d.itervalues: an iterator over the values of d
    print value,

2 1 3

for value in d.values():
    # d.values() -> [2, 1, 3]
    print value,

2 1 3

遍历keys和values

for key, value in d.iteritems():
    # d.iteritems: an iterator over the (key, value) items
    print key,'corresponds to',d[key]

y corresponds to 2
x corresponds to 1
z corresponds to 3

for key, value in d.items():
    # d.items(): list of d's (key, value) pairs, as 2-tuples
    # [('y', 2), ('x', 1), ('z', 3)]
    print key,'corresponds to',value

y corresponds to 2
x corresponds to 1
z corresponds to 3