默认字典的妙用

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In [1]: stu = [('wang', 1), ('zhang', 4), ('fu', 2), ('li', 3), ('fu', 7), ('wa
   ...: ng', 2), ('wang', 8)]

In [2]: dict1 = {}
In [3]: for k, v in stu:
   ...:     dict1.setdefault(k, []).append(v)  # 这是最关键的
   ...:
   ...:

In [4]: for k2, v2 in dict1.items():
   ...:     print(k2, v2)
   ...:
wang [1, 2, 8]
zhang [4]
fu [2, 7]
li [3]

In [6]: