Singly linked list implementation in python 3

Question

I have implemented a Singly linked list. It works well. But if you think something needs to be improved, say it. This code was tested in Python 3.7.4.

class Node(object): def __init__(self, data): self.data = data self.nextNode = None class LinkedList(object): def __init__(self): self.head = None self.size = 0 # O(1) !!! def insertStart(self, data): self.size = self.size + 1 newNode = Node(data) if not self.head: self.head = newNode else: newNode.nextNode = self.head self.head = newNode def remove(self, data): if self.head is None: return self.size = self.size - 1 currentNode = self.head previousNode = None while currentNode.data != data: previousNode = currentNode currentNode = currentNode.nextNode if previousNode is None: self.head = currentNode.nextNode else: previousNode.nextNode = currentNode.nextNode # O(1) def size1(self): return self.size # O(N) def insertEnd(self, data): self.size = self.size + 1 newNode = Node(data) actualNode = self.head while actualNode.nextNode is not None: actualNode = actualNode.nextNode actualNode.nextNode = newNode def traverseList(self): actualNode = self.head while actualNode is not None: print(actualNode.data) actualNode = actualNode.nextNode 

Answer 1

You are missing several important things for this code:

Type Annotations

Python 3.7 supports type annotations. Especially for a container class like this, you should fully use them.

Initializer parameters

Python containers generally all provide builder methods or class initializer functions that take other containers and use their contents. Consider:

• dict(iterable,**kwarg)
• list(iterable)
• set(iterable)
• str(object=b'', encoding='utf-8', errors='strict')
• tuple(iterable)

If you're writing a Python container, you need to conform to expectations. I expect to be able to initialize the container when I create it.

Protocols & Magic methods

Python has a well-established set of protocols for implementing containers. You just have to decide what kind of container you're writing.

I would suggest that a singly-linked list is an Iterable, a Sequence, a MutableSequence and possibly a Set type.