您正在体验的是引用的概念。Python中的所有对象都有一个引用，当您将一个名称分配给两个名称a和时b，这将导致两者a并b指向 _同一_对象。
>>> a = range(3)
>>> b = a # same object
>>> b.append(3)
>>> a, b # same contents
([0, 1, 2, 3], [0, 1, 2, 3])
随着名单，你可以创建一个新的列表b是一个 副本， 另一个a使用b = a[:]。
>>> a = range(3)
>>> b = a[:] # make b a new copy of a
>>> b.append(3)
>>> a, b # a is left unchanged
([0, 1, 2], [0, 1, 2, 3])
有关任何对象的更通用解决方案，请使用copy模块。浅表副本将复制要复制的对象中存储的引用，而深表副本将递归地创建所有对象的新副本。
>>> a = [range(2), range(3)]
>>> b = copy.copy(a) # shallow copy of a, equivalent to a[:]
>>> b[0] = range(4)
>>> a, b # setting an element of b leaves a unchanged
([[0, 1], [0, 1, 2]], [[0, 1, 2, 3], [0, 1, 2]])
>>> b[1].append(3)
>>> a, b # modifying an element of b modifies the element in a
([[0, 1], [0, 1, 2, 3]], [[0, 1, 2, 3], [0, 1, 2, 3]])
>>> a = [range(2), range(3)]
>>> b = copy.deepcopy(a) # deep recursive copy of a
>>> b[1].append(3)
>>> a, b # modifying anything in b leaves a unchanged
([[0, 1], [0, 1, 2]], [[0, 1], [0, 1, 2, 3]])
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