python请选择使用顺序表或链表（单链表或双链表）实现以下操作。要求设计菜单，根据菜单提示进行操作：插入一个新元素到第i个位置；删除第i个位置的元素；显示线性表中所有元素的值；检索表中第i个元素；求表的长度等运算。

在Python中，我们可以选择使用链表来实现这个操作，因为链表更适合频繁的插入和删除操作，尤其是单链表。以下是使用Python实现一个简单的链表数据结构以及对应的操作：

class Node:
    def __init__(self, data=None):
        self.data = data
        self.next = None

class LinkedList:
    def __init__(self):
        self.head = None

    # 插入元素到第i个位置
    def insert_at(self, i, data):
        if not self.head:
            self.head = Node(data)
        else:
            current = self.head
            for _ in range(i - 1):
                if current.next is None:
                    break
                current = current.next
            new_node = Node(data)
            new_node.next = current.next
            current.next = new_node

    # 删除第i个位置的元素
    def delete_at(self, i):
        if not self.head or i < 1:
            return
        if i == 1:
            self.head = self.head.next
        else:
            current = self.head
            for _ in range(i - 2):
                if current.next is None:
                    break
                current = current.next
            current.next = current.next.next

    # 显示所有元素
    def display(self):
        elements = []
        current = self.head
        while current:
            elements.append(current.data)
            current = current.next
        print(elements)

    # 检索第i个元素
    def retrieve(self, i):
        if i <= 0:
            return None
        current = self.head
        for _ in range(i):
            if current is None:
                break
            current = current.next
        return current.data if current else None

    # 计算表长
    def length(self):
        count = 0
        current = self.head
        while current:
            count += 1
            current = current.next
        return count

# 菜单操作示例
ll = LinkedList()
# ... (根据需求调用上述方法)