Types of Data Structures to Know for Principles of Data Science

Understanding different data structures is key in data science. Each type, from arrays to graphs, has unique strengths and weaknesses that impact how we store, access, and manipulate data efficiently in various applications.

1. Arrays

   • Fixed-size data structure that stores elements of the same type in contiguous memory locations.
   • Allows for efficient access to elements using an index, making retrieval operations fast (O(1) time complexity).
   • Insertion and deletion operations can be costly (O(n) time complexity) due to the need to shift elements.

2. Linked Lists

   • Composed of nodes, where each node contains data and a reference (or pointer) to the next node.
   • Dynamic size allows for efficient insertions and deletions (O(1) time complexity) compared to arrays.
   • Accessing elements is slower (O(n) time complexity) since it requires traversal from the head node.

3. Stacks

   • Last-In-First-Out (LIFO) data structure where the last element added is the first to be removed.
   • Supports two primary operations: push (add an element) and pop (remove the top element).
   • Useful for scenarios like function call management, undo mechanisms, and expression evaluation.

4. Queues

   • First-In-First-Out (FIFO) data structure where the first element added is the first to be removed.
   • Supports two primary operations: enqueue (add an element) and dequeue (remove the front element).
   • Commonly used in scheduling tasks, managing resources, and handling asynchronous data.

5. Trees

   • Hierarchical data structure with a root node and child nodes, forming a parent-child relationship.
   • Binary trees, where each node has at most two children, are fundamental for efficient searching and sorting (e.g., binary search trees).
   • Useful for representing hierarchical data, such as file systems and organizational structures.

6. Graphs

   • Consists of vertices (nodes) connected by edges, representing relationships between entities.
   • Can be directed or undirected, weighted or unweighted, allowing for diverse applications in networking and social connections.
   • Essential for algorithms like shortest path and network flow analysis.

7. Hash Tables

   • Data structure that uses a hash function to map keys to values, allowing for fast data retrieval.
   • Average time complexity for search, insert, and delete operations is O(1), making it efficient for large datasets.
   • Collision resolution techniques (e.g., chaining, open addressing) are crucial for maintaining performance.

8. Heaps

   • Specialized tree-based data structure that satisfies the heap property (max-heap or min-heap).
   • Allows for efficient retrieval of the maximum or minimum element (O(1) time complexity) and supports insertion and deletion (O(log n) time complexity).
   • Commonly used in priority queues and sorting algorithms (e.g., heapsort).

9. Matrices

   • Two-dimensional data structure consisting of rows and columns, used to represent numerical data.
   • Supports various operations such as addition, multiplication, and transposition, essential in linear algebra.
   • Widely used in data science for representing datasets, images, and mathematical computations.

10. Dictionaries

    • Key-value pair data structure that allows for fast data retrieval based on unique keys.
    • Average time complexity for search, insert, and delete operations is O(1), making it efficient for lookups.
    • Useful for storing and managing data with unique identifiers, such as user profiles and configuration settings.