如何将项目递归添加到列表?

问题描述：

当前，我正在研究一个问题.给了我一个列表，该列表的元素可以包含其他列表，列表列表或整数.例如，我可能会收到:

Currently, I'm working on a problem. I am given a list, whose elements may contain other lists, lists of lists, or integers. For example, I may receive:

[[[[], 1, []], 2, [[], 3, []]], 4, [[[], 5, []], 6, [[], 7, [[], 9, []]]]]

我的目标是解析数组，并将仅整数附加到新列表中.到目前为止，这是我所做的:

My goal is to parse the array, and append only the integers to a new list. Here is what I have done so far:

def fun(a):
    if a == []:
        return None
    elif type(a) == int:
        print("Found a digit: ", a)
        return a
    for i in a:
        fun(i)

当前，此函数递归地遍历列表并成功找到每个整数；现在，我在将这些整数追加到新列表中并在最后返回该列表时遇到了问题.输出应该是这样的:

Currently, this function recursively goes through the list and successfully finds each integer; now, I am having an issue with appending those integers to a new list, and returning that list at the very end. The output should be like this:

[1,2,3,4,5,6,7,9]

有指针吗?

答

将要附加的列表作为参数传递.

Pass the list to append to as a parameter.

def fun(a, result):
    if type(a) == int:
        print("Found a digit: ", a)
        result.append(a)
    else:
        for i in a:
            fun(i, result)
old_list = [[[[], 1, []], 2, [[], 3, []]], 4, [[[], 5, []], 6, [[], 7, [[], 9, []]]]]
new_list = []
fun(old_list, new_list)
print(new_list)

如果需要原始功能签名，可以将其分为两个功能.

If you need the original function signature, you can split this into two functions.

def fun(a):
    result = []
    fun_recursive(a, result)
    return result

fun_recursive()的定义如上.

如何将项目递归添加到列表?

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