python - 用不同列表中的项目递归替换列表中的项目

Question

我已经通过递归实现了完全相同的功能，我还想要一个不带递归的版本，因为 Python 有递归限制并且共享数据时存在问题。

sublist2 = [{'nothing': "Notice This"}]
sublist1 = [{'include':[sublist2]}]

mainlist = [{'nothing': 1}, {'include':[sublist1, sublist2]},
            {'nothing': 2}, {'include':[sublist2]}]

待办事项中要填写什么？

for i in mainlist:
    if 'nothing' in i:
         # Do nothing
    else if 'include' in i:
         # Todo
         # Append the contents of the list mentioned recursively
         # in it's own place without disrupting the flow

运行后的预期结果

mainlist = [{'nothing': 1}, 
            {'nothing': "Notice This"}, {'nothing': "Notice This"}, 
            {'nothing':2}, 
            {'nothing': "Notice This"}]

如果您注意到 sublist1 引用了 sublist2。原来是这个原因

{'include':[sublist1, sublist2]} 替换为

{'nothing':"注意这一点"}, {'nothing':"注意这一点"}

我尝试过以下方法

Inserting values into specific locations in a list in Python

How to get item's position in a list?

Answer 1

不使用递归，您只需查看第 n 个元素并就地更改它，直到它不需要任何进一步处理。

sublist2 = [{'nothing': "Notice This"}]
sublist1 = [{'include':[sublist2]}]

mainlist = [{'nothing': 1}, {'include':[sublist1, sublist2]},
            {'nothing': 2}, {'include':[sublist2]}]

index = 0
while index < len(mainlist):
    if 'nothing' in mainlist[index]:
        index += 1
    elif 'include' in mainlist[index]:
        # replace the 'include' entries with their corresponding list
        mainlist[index:index+1] = mainlist[index]['include']
    elif isinstance(mainlist[index], list):
        # if an entry is a list, replace it with its entries
        mainlist[index:index+1] = mainlist[index]

注意分配给条目l[0]和分配给切片l[0:1]之间的区别

>>> l = [1, 2, 3, 4]
>>> l[3] = ['a', 'b', 'c']
>>> l
[1, 2, 3, ['a', 'b', 'c']]
>>> l[0:1] = ['x', 'y', 'z']
>>> l
>>> ['x', 'y', 'z', 2, 3, ['a', 'b', 'c']]