Ultimate Python Cheat Sheet: Practical Python For Everyday Tasks

A cheat sheet for performing practical Python tasks, including working with files, HTTP APIs, lists, dictionaries, operating system, mathematical operations, databases, async IO, networks, dates and times, decorators, object-oriented programming, GraphQL, and regular expressions.

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Apr 14, 2024•36m read time•From medium.com

Table of contents

Ultimate Python Cheat Sheet: Practical Python For Everyday Tasks Working With Files 1. Reading a File 2. Writing to a File 3. Appending to a File 4. Reading Lines into a List 5. Iterating Over Each Line in a File 6. Checking If a File Exists 7. Writing Lists to a File 8. Using With Blocks for Multiple Files 9. Deleting a File 10. Reading and Writing Binary Files Working With Simple HTTP APIs 1. Basic GET Request 2. GET Request with Query Parameters 3. Handling HTTP Errors 4. Setting Timeout for Requests 5. Using Headers in Requests 6. POST Request with JSON Payload 7. Handling Response Encoding 8. Using Sessions with Requests 9. Handling Redirects 10. Streaming Large Responses Working With Lists 1. Creating a List 2. Appending to a List 3. Inserting into a List 4. Removing from a List 5. Popping an Element from a List 6. Finding the Index of an Element 7. List Slicing 8. List Comprehension 9. Sorting a List 10. Reversing a List Working With Dictionaries 1. Creating a Dictionary 2. Adding or Updating Entries 3. Removing an Entry 4. Checking for Key Existence 5. Iterating Over Keys 6. Iterating Over Values 7. Iterating Over Items 8. Dictionary Comprehension 9. Merging Dictionaries 10. Getting a Value with Default Working With The Operating System 1. Navigating File Paths 2. Listing Directory Contents 3. Creating Directories 4. Removing Files and Directories 5. Executing Shell Commands 6. Working with Environment Variables 7. Changing the Current Working Directory 8. Path Existence and Type 9. Working with Temporary Files 10. Getting System Information Working With CLI — STDIN, STDOUT, STDERR 1. Reading User Input 2. Printing to STDOUT 3. Formatted Printing 4. Reading Lines from STDIN 5. Writing to STDERR 6. Redirecting STDOUT 7. Redirecting STDERR 8. Prompting for Passwords 9. Command Line Arguments 10. Using Argparse for Complex CLI Interactions Working With Mathematical Operations and Permutations 1. Basic Arithmetic Operations 2. Working with Complex Numbers 3. Mathematical Functions 4. Generating Permutations 5. Generating Combinations 6. Random Number Generation 7. Working with Fractions 8. Statistical Functions 9. Trigonometric Functions 10. Handling Infinity and NaN Working With Databases 1. Establishing a Connection 2. Creating a Cursor 3. Executing a Query 4. Fetching Query Results 5. Inserting Records 6. Updating Records 7. Deleting Records 8. Creating a Table 9. Dropping a Table 10. Using Transactions Working With Async IO (Asyncrounous Programming)1. Defining an Asynchronous Function 2. Running an Asynchronous Function 3. Awaiting Multiple Coroutines 4. Creating Tasks 5. Asynchronous Iteration 6. Using Asynchronous Context Managers 7. Handling Exceptions in Asynchronous Code 8. Asynchronous Generators 9. Using Semaphores 10. Event Loops Working With Networks, Sockets, and Network Interfaces 1. Creating a Socket 2. Connecting to a Remote Server 3. Sending Data 4. Receiving Data 5. Closing a Socket 6. Creating a Listening Socket 7. Accepting Connections 8. Non-blocking Socket Operations 9. Working with UDP Sockets 10. Enumerating Network Interfaces Working With Pandas Library (Dataframes)1. Creating a DataFrame 2. Reading Data from a CSV File 3. Inspecting the First Few Rows 4. Selecting Columns 5. Filtering Rows 6. Creating New Columns 7. Grouping and Aggregating Data 8. Merging DataFrames 9. Handling Missing Data 10. Pivoting and Reshaping Data Working With Numpy Library (Arrays)1. Creating a NumPy Array 2. Array of Zeros or Ones 3. Creating a Range of Numbers 4. Creating a Linearly Spaced Array 5. Reshaping an Array 6. Basic Array Operations 7. Matrix Multiplication 8. Accessing Array Elements 9. Boolean Indexing 10. Aggregations and Statistics Working With Matplotlib Library (Data Visualization)1. Creating a Basic Plot 2. Adding Titles and Labels 3. Creating a Scatter Plot 4. Customizing Line Styles and Markers 5. Creating Multiple Plots on the Same Axes 6. Creating Subplots 7. Creating a Histogram 8. Adding a Legend 9. Customizing Ticks 10. Saving Figures Working With Scikit-Learn Library (Machine Learning)1. Loading a Dataset 2. Splitting Data into Training and Test Sets 3. Training a Model 4. Making Predictions 5. Evaluating Model Performance 6. Using Cross-Validation 7. Feature Scaling 8. Parameter Tuning with Grid Search 9. Pipeline Creation 10. Saving and Loading a Model Working With Plotly Library (Interactive Data Visualization)1. Creating a Basic Line Chart 2. Creating a Scatter Plot 3. Creating a Bar Chart 4. Creating a Pie Chart 5. Creating a Histogram 6. Creating Box Plots 7. Creating Heatmaps 8. Creating 3D Surface Plots 9. Creating Subplots 10. Creating Interactive Time Series Working With Dates and Times 1. Getting the Current Date and Time 2. Creating Specific Date and Time 3. Formatting Dates and Times 4. Parsing Dates and Times from Strings 5. Working with Time Deltas 6. Comparing Dates and Times 7. Extracting Components from a Date/Time 8. Working with Time Zones 9. Getting the Weekday 10. Working with Unix Timestamps Working With More Advanced List Comprehensions and Lambda Functions 1. Nested List Comprehensions 2. Conditional List Comprehensions 3. List Comprehensions with Multiple Iterables 4. Using Lambda Functions 5. Lambda Functions in List Comprehensions 6. List Comprehensions for Flattening Lists 7. Applying Functions to Elements 8. Using Lambda with Map and Filter 9. List Comprehensions with Conditional Expressions 10. Complex Transformations with Lambda Working With Object Oriented Programming 1. Defining a Class 2. Creating an Instance 3. Invoking Methods 4. Inheritance 5. Overriding Methods 6. Polymorphism 7. Encapsulation 8. Composition 9. Class Methods and Static Methods 10. Properties and Setters Working With Decorators 1. Basic Decorator 2. Decorator with Arguments 3. Using functools.wraps 4. Class Decorator 5. Decorator with Arguments 6. Method Decorator 7. Stacking Decorators 8. Decorator with Optional Arguments 9. Class Method Decorator 10. Decorator for Static Method Working With GraphQL 1. Setting Up a GraphQL Client 2. Executing a Simple Query 3. Executing a Query with Variables 4. Mutations 5. Handling Errors 6. Subscriptions 7. Fragments 8. Inline Fragments 9. Using Directives 10. Batching Requests Working With Regular Expressions 1. Basic Pattern Matching 2. Compiling Regular Expressions 3. Matching at the Beginning or End 4. Finding All Matches 5. Search and Replace (Substitution)6. Splitting a String 7. Escaping Special Characters 8. Grouping and Capturing 9. Non-Capturing Groups 10. Lookahead and Lookbehind Assertions 11. Flags to Modify Pattern Matching Behavior 12. Using Named Groups 13. Matching Across Multiple Lines 14. Lazy Quantifiers 15. Verbose Regular Expressions Working With Strings 1. Concatenating Strings 2. String Formatting with str.format 3. Formatted String Literals (f-strings)4. String Methods — Case Conversion 5. String Methods — strip , rstrip , lstrip 6. String Methods — startswith , endswith 7. String Methods — split , join 8. String Methods — replace 9. String Methods — find , index 10. String Methods — Working with Characters 11. String Methods — isdigit , isalpha , isalnum 12. String Slicing 13. String Length with len 14. Multiline Strings 15. Raw Strings Working With Web Scraping 1. Fetching Web Pages with requests 2. Parsing HTML with BeautifulSoup 3. Navigating the HTML Tree 4. Using CSS Selectors 5. Extracting Data from Tags 6. Handling Relative URLs 7. Dealing with Pagination 8. Handling AJAX Requests 9. Using Regular Expressions in Web Scraping 10. Respecting robots.txt 11. Using Sessions and Cookies 12. Scraping with Browser Automation ( selenium Library)13. Error Handling in Web Scraping 14. Asynchronous Web Scraping 15. Data Storage (CSV, Database)Working With pip (Package Management)1. Installing a Package 2. Listing Installed Packages 3. Upgrading a Package 4. Uninstalling a Package 5. Searching for Packages 6. Installing Specific Versions of a Package 7. Generating a Requirements File 8. Installing Packages from a Requirements File 9. Using Virtual Environments 10. Checking Package Dependencies Working With Common Built-in Functions and Packages 1. os - Operating System Interface 2. sys - System-specific Parameters and Functions 3. datetime - Basic Date and Time Types 4. math - Mathematical Functions 5. random - Generate Pseudo-random Numbers 6. json - JSON Encoder and Decoder 7. re - Regular Expressions 8. urllib - URL Handling Modules 9. http - HTTP Modules 10. subprocess - Subprocess Management 11. socket - Low-level Networking Interface 12. threading - Thread-based Parallelism 13. multiprocessing - Process-based Parallelism 14. argparse - Parser for Command-line Options, Arguments, and Sub-commands 15. logging - Logging Facility 16. unittest - Unit Testing Framework 17. pathlib - Object-oriented Filesystem Paths 18. functools - Higher-order Functions and Operations on Callable Objects 19. collections - Container Data Types 20. itertools - Functions Creating Iterators for Efficient Looping 21. hashlib - Secure Hash and Message Digest Algorithms 22. csv - CSV File Reading and Writing 23. xml.etree.ElementTree - The ElementTree XML API 24. sqlite3 - DB-API 2.0 Interface for SQLite Databases 25. tkinter - GUI Toolkit 26. pickle - Python Object Serialization 27. io - Core Tools for Working with Streams 28. time - Time Access and Conversions 29. calendar - General Calendar-related Functions 30. queue - A Synchronized Queue Class 31. shutil - High-level File Operations 32. glob - Unix Style Pathname Pattern Expansion 33. tempfile - Generate Temporary Files and Directories 34. bz2 - Support for Bzip2 Compression 35. gzip - Support for Gzip Compression 36. ssl - TLS/SSL Wrapper for Socket Objects 37. imaplib - IMAP4 Protocol Client 38. smtplib - SMTP Protocol Client 39. email - Managing Email Messages 40. base64 - Base16, Base32, Base64, Base85 Data Encodings 41. difflib - Helpers for Computing Deltas 42. gettext - Multilingual Internationalization Services 43. locale - Internationalization Services 44. secrets - Generate Secure Random Numbers for Managing Secrets 45. uuid - UUID Objects According to RFC 4122 46. html - HyperText Markup Language Support 47. ftplib - FTP Protocol Client 48. tarfile - Read and Write Tar Archive Files