Singly linked list¶

Package information¶

Distribution:         lazypye-data-structures
Repository directory: packages/data-structures
Module:               lazypye.data_structures.singly_linked_list
Public import:         lazypye.data_structures.SinglyLinkedList

Installation¶

Install only the data-structures distribution directly from the repository:

py -m pip install "git+https://github.com/MonoChromatical/LazyPye.git#subdirectory=packages/data-structures"

For the reusable installation blueprint and the distinction between distribution names and import paths, see Getting started.

Import¶

from lazypye.data_structures import SinglyLinkedList

Description¶

A singly linked list stores values in nodes connected in one direction. This implementation supports appending data, inserting and removing middle values, retrieving data by position, removing either end, reporting its length, and displaying all stored values.

Private node design¶

SinglyLinkedList is the only public class. The private _Node type, head and tail links, and node connections are implementation details. Public methods accept and return data, preventing callers from accidentally corrupting links.

Positions¶

Positions are zero-based. The first value is at position 0.

add_middle() accepts positions from 1 through len(linked) - 1 and inserts before the value currently at that position. It rejects position 0 and the append position len(linked).

remove_middle() accepts positions from 1 through len(linked) - 2. Use delete_first() or delete_last() for boundary removal.

Complete example¶

from lazypye.data_structures import SinglyLinkedList

linked = SinglyLinkedList[int]()
linked.add_data(10)
linked.add_data(30)
linked.add_middle(1, 20)

print(linked.display_node(1))
linked.display_linkedlist()

20
10 → 20 → 30 → None

Public interface¶

SinglyLinkedList()¶

Creates an empty linked list. An optional type argument can describe its data:

names = SinglyLinkedList[str]()

len(linked)¶

Returns the number of stored values.

linked = SinglyLinkedList[int]()
linked.add_data(10)
print(len(linked))

add_data(data)¶

Appends data to the end of the list and returns None.

linked.add_data(20)
linked.add_data(30)

add_middle(position, data)¶

Inserts data before the existing value at a middle position.

param position:: Integer from 1 through len(linked) - 1.
param data:: Value to insert.
returns:: None.
raises TypeError:: If position is not an integer.
raises IndexError:: If it is zero, an append position, or outside the list.

linked = SinglyLinkedList[int]()
linked.add_data(10)
linked.add_data(30)
linked.add_middle(1, 20)

display_node(position)¶

Returns the data at position, never the private node.

param position:: Zero-based position to retrieve.
returns:: The stored data.
raises TypeError:: If position is not an integer.
raises IndexError:: If it is outside the list.

print(linked.display_node(1))

display_linkedlist()¶

Prints every value in order followed by None. An empty list prints None.

returns:: None.

linked.display_linkedlist()

10 → 20 → 30 → None

delete_first()¶

Removes and returns the first value.

returns:: The removed data.
raises IndexError:: If the list is empty.

first = linked.delete_first()
print(first)

remove_middle(position)¶

Removes and returns data at a non-boundary position.

param position:: Integer from 1 through len(linked) - 2.
returns:: The removed data.
raises TypeError:: If position is not an integer.
raises IndexError:: If it is a boundary, outside the list, or no middle exists.

linked = SinglyLinkedList[int]()
linked.add_data(10)
linked.add_data(20)
linked.add_data(30)
removed = linked.remove_middle(1)
print(removed)

delete_last()¶

Removes and returns the final value.

returns:: The removed data.
raises IndexError:: If the list is empty.

last = linked.delete_last()
print(last)

Edge cases¶

Retrieving any position from an empty list raises IndexError.
Removing an end value from an empty list raises IndexError.
Middle insertion requires at least two existing values.
Middle removal requires at least three existing values.
Negative and out-of-range positions raise IndexError.
Non-integer positions, including booleans, raise TypeError.

API reference¶

See Data structures API for generated signatures and docstrings.