List in Python

Complete and in-depth guide to Python lists: creation, indexing, slicing, mutation, traversal, searching, insertion, deletion, sorting, copying, nested lists, unpacking, built-in functions, and powerful list comprehensions.

List Creation

Lists are ordered, mutable collections in Python. They can store mixed data types and grow dynamically.

1. List Literal

Create lists using square brackets.

2. list() Constructor

Convert iterables to lists.

List Fundamentals

Lists are dynamic and mutable.

1. Getting List Size

Use len().

2. Accessing Elements

Index starts from 0.

3. Slicing

Extract sublists.

4. Updating Elements

Lists are mutable.

Insertion & Removal

Python provides multiple mutation methods.

1. append & pop

Add/remove from end.

2. insert & remove

Insert at index / remove by value.

3. del & clear

Delete by index or clear list.

Traversing Lists

Iterate using for, enumerate, or while.

1. for Loop

Iterate directly over values.

2. enumerate()

Get index and value.

Searching

Find elements safely.

1. Membership Check

Use in operator.

2. index()

Find index of value.

Sorting

Sort lists in place or return new list.

1. sort()

Sort in place.

2. sorted()

Returns new sorted list.

List Comprehension (Power Feature)

List comprehension is Python’s most powerful feature for transforming and filtering lists.

1. Basic Transformation (map alternative)

Transform each element.

2. Filtering (filter alternative)

Condition inside comprehension.

3. Find Alternative

Using next().

4. reduce Alternative

Use sum() or functools.reduce.

5. Nested Comprehension

Flatten nested list.

Shallow & Deep Copy

Understand reference behavior.

1. Shallow Copy

Use slicing or copy().

2. Deep Copy

Use copy module.

Packing & Unpacking

Packing collects multiple values into a list. Unpacking extracts elements from a list into variables. Python also supports extended unpacking using the * operator.

1. Packing Values into a List

Multiple values grouped into one list.

2. Basic Unpacking

Extract list elements into variables.

3. Extended Unpacking (*)

Capture remaining elements using *.

4. Unpacking Inside Loops

Unpack list elements while iterating.

Pattern Matching with Lists

Structural pattern matching allows matching list shapes and destructuring values safely.

1. Basic List Pattern

Match fixed-length list.

2. Matching Specific Values

Match certain list patterns.

3. Variable Length Matching (*)

Match lists of unknown length.

4. Pattern with Guard Condition

Add condition after matching.