python - 将元组列表转换为深层嵌套列表

Question

我有一个程序可以生成以下元组列表:

[('Government and politics', 2), ('Government', 3), ('Capital punishment', 4), ('Federal representation', 4), ('Politics', 3)]

其中数字反射(reflect)了层次结构。我想知道是否有一种递归方法可以将此元组列表转换为嵌套列表，如下所示:

['Government and politics', ['Government', ['Capital punishment', 'Federal representation'], 'Politics']]

Answer 1

在这种情况下没有必要使用递归:

def nest(data, base=0):
    result = []
    for item, level in data:
        target = result
        for depth in range(base, level):
            if not (len(target) > 0 and isinstance(target[-1], list)):
                target.append([])
            target = target[-1]
        target.append(item)
    return result

此函数的外部循环迭代数据中的item, level 对，内部循环向下钻取到适当的深度，根据需要创建新的子列表。

base 参数是数据中的最低级别，在本例中为 2。这是实际操作:

>>> data = [
...     ('Government and politics', 2),
...     ('Government', 3),
...     ('Capital punishment', 4),
...     ('Federal representation', 4),
...     ('Politics', 3)
... ]

>>> nest(data, 2)
['Government and politics', ['Government', ['Capital punishment', 'Federal representation'], 'Politics']]