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PythonOneLiners

PYTHON REFRESHER

  • Purpose: Refresh knowledge of basic Python data structures, keywords, control flow operations, and fundamentals.

  • Target Audience: Intermediate Python programmers aiming for expert level.

  • Importance of Basics: A deep understanding helps in seeing the larger picture, essential for roles like tech lead or computer science professor.

    • Professors often possess profound knowledge of the basics to identify research gaps.

Basic Data Structures

  • Importance: Understanding data structures is fundamental for various programming tasks like machine learning, website management, and algorithm development.

Numerical Data Types and Structures

  • Integer: A whole number (e.g., 3).

  • Float: A number with floating-point precision (e.g., 3.14).

  • Python offers various built-in numerical operations, including type conversions.

Arithmetic Operations

  • Examples using numerical data types (Listing 1-1):

    • x, y = 3, 2

    • Operations include addition, subtraction, multiplication, division, integer division, modulo, negation, absolute value, casting, and exponentiation.

  • Integer Division: Uses // operator which rounds down.

Booleans

  • Boolean data type has two values: True and False.

  • Internally represented using integers (0 for False, 1 for True).

    • Example: x = 1 > 2 results in False.

  • Important keywords for logical operations: and, or, not.

    • Combinations yield more complex expressions.

    • Example (Listing 1-3): Various logical expressions using these keywords.

Boolean Operator Precedence

  • Order of application matters in expressions.

    • Example interpretations of the expression regarding weather conditions.

  • Preferred order of operations: not > and > or.

    • Example: Listing 1-4 illustrates with True/False evaluations.

Strings

  • Definition: Sequences of characters in Python; immutable.

  • Common ways to create strings: single quotes, double quotes, triple quotes.

  • Whitespace characters: Newline (\n), space (\s), tab (\t).

Important String Methods (Listing 1-5)

  • Functions such as strip, lower, upper, startswith, endswith, find, replace, join, length, and containment check.

  • Strings can be manipulated using these methods for various applications.

The Keyword None

  • Represents absence of a value (similar to null in Java).

  • Example: None is not equal to any numerical values or empty container types (Listing 1-6).

Container Data Structures

Lists

  • Definition: Sequence of elements, mutable.

  • Example of list creation and properties.

  • Adding Elements: Common methods to append, insert, or concatenate.

  • Removing Elements: Use remove(x) method to delete items.

  • Reversing and Sorting: Methods reverse() and sort() modify the original list.

Stacks

  • Concept: Last-In, First-Out (LIFO) structure; intuitive operation mimicking a stack of papers.

    • Uses append() and pop() methods.

Sets

  • Definition: Unordered collection of unique elements, all elements must be hashable.

  • Example: Creating a set shows unique properties and hashability checks (Listing 1-8).

  • Key properties: unordered, unique elements—no duplicates.

Dictionaries

  • Definition: Stores (key, value) pairs.

  • Example: Retrieve and modify values using keys.

  • Methods to access keys, values, and items for iteration.

Control Flow

Conditional Execution

  • Keywords: if, else, elif for decision making (Listing 1-10).

Loops

  • Types: for loops and while loops for repeated execution.

  • Termination methods: loop conditions or break statement (Listing 1-12).

  • Using continue: Skips to the next iteration without terminating the loop (Listing 1-13).

Functions

  • Definition: Reusable code constructs, defined with def keyword.