嘗試從except塊中的列表中刪除記錄時，為什么會出現“ IndexError：列表索引超出范圍”

Question

當我嘗試運行此函數時，出現索引錯誤：列表超出范圍。 當我嘗試使用list.remove(list[i])時，錯誤發生在代碼的except塊中。 不知道為什么我會超出范圍的錯誤，任何幫助將不勝感激！

我已經嘗試過使用函數周圍的各種打印語句進行調試，並且我發現我的記錄很好，每當我嘗試刪除except塊中的記錄時，它只會拋出此錯誤。

def subnet_insertion_sort(list):
    with open('bad_subnets.csv', 'w') as z:
        # Traverse through 1 to len(list)
        for i in range(1, len(list)):
            # extracts subnet from current list observed in list
            # and casts it as a ip_network objects
            try:
                key_subnet = ipaddress.ip_network(unicode(list[i][0]))

                j = i - 1
                # Move elements of list[0..i-1], that are
                # greater than key, to one position ahead
                # of their current position
                while (j >= 0 and key_subnet < ipaddress.ip_network(unicode(list[j][0]))):
                        temp = list[j]
                        list[j] = list[j + 1]
                        list[j + 1] = temp
                        j -= 1
            except:
                print("invalid subnet found: " + list[i][0] +  " on line " + str(i) + ". It has been added to bad_subnets.csv")
                writer_z = csv.writer(z)
                writer_z.writerow(list[i])
                list.remove(list[i])
                continue

        return list

我的預期結果是該函數正常運行，並且我收到了一個沒有無效子網的列表，但是我的實際輸出是索引錯誤：列表超出范圍。

Answer 1

一旦您開始for循環

for i in range(1,len(list))

如果原始列表的長度為10 ，它將轉換為

for i in range(1,10)

如果在循環中從列表中刪除項目，則不會更改范圍。 一旦范圍超過當前列表的長度，將導致索引錯誤。

Answer 2

從不更改列表，而是創建一個新列表：

def subnet_insertion_sort(ipaddresses):
    valid_addresses = []
    with open('bad_subnets.csv', 'w') as z:
        writer_z = csv.writer(z)
        for i, address in enumerate(ipaddresses):
            try:
                key_subnet = ipaddress.ip_network(address)
            except ValueError:
                print("invalid subnet found: {} on line {} It has been added to bad_subnets.csv".format(address, i)
                writer_z.writerow(address)
            else:
                valid_addresses(key_subnet)
    return sorted(valid_addresses)