如何循環遍歷列表中的項目不斷附加在循環中的列表？ (how to loop through a list where the items of the list are constantly appended in the loop?)

問題描述

如何循環遍歷列表中的項目不斷附加在循環中的列表？ (how to loop through a list where the items of the list are constantly appended in the loop?)

我是 Python 新手。我想寫一個搜索算法，可以實現如下：給定一個點→搜索一個附近滿足某個條件的點→用那個新點搜索下一個附近的新點→重複這個直到找不到附近的新點. 這是我的腳本，new_point_near_this_point() 是一個自定義函數，它返回布爾值是否存在滿足條件的附近點。init_point 是起點。

lst = [init_point]
for i in lst[‑1]:
    if new_point_near_this_point(i):
        lst.append(new_point)
    else:
        break

但是，這不起作用，因為它只會循環通過一個初始點。我想知道如何實現一個可以循環遍歷列表的搜索算法，其中列表的項目在循環中不斷附加（每次迭代一次）？

參考解法

方法 1:

You should change new_point_near_this_point so that it does not just return a boolean, but the nearby point that was found. Otherwise you have no way to progress to the next point.

So assuming that a point is returned by new_point_near_this_point when there is one (or None otherwise), you could do it like this:

list = []
point = init_point
while point:
    list.append(point)
    point = new_point_near_this_point(point)

方法 2:

With the same assumption as @trincot, that new_point_near_this_point returns a true new point or a false value if there isn't one:

lst = [init_point]
for point in lst:
    if new_point := new_point_near_this_point(point):
        lst.append(new_point)

For example, with

init_point = 0
def new_point_near_this_point(point):
    if point < 5:
        return point + 1

you get the list [0, 1, 2, 3, 4, 5].

(by Shaun Han、trincot、Kelly Bundy)

參考文件

1. how to loop through a list where the items of the list are constantly appended in the loop? (CC BY‑SA 2.5/3.0/4.0)