Python Built-In functions simplified

This year, I'm diving into cloud computing. As a starting point, I enrolled in the AWS re/Start Cloud Foundational Course. I'm currently in week 6 of 12 and tackling the Python module. I created this blog as a quick reference for Python built-in functions with examples. Hope it helps someone else.

Table of Contents

• Type Conversion Functions
• Mathematical Functions
• Iterables and Sequences
• Input and Output
• Object and Type Checking
• Memory and Object Management
• Functional Programming
• Other Useful Functions

1. Type Conversion Functions

These functions convert data from one type to another.

num_str = "100" num_int = int(num_str) # Converts string to integer num_float = float(num_str) # Converts string to float bool_val = bool(1) # Converts integer to boolean (True) list_val = list("hello") # Converts string to list of characters tuple_val = tuple([1, 2, 3]) # Converts list to tuple set_val = set([1, 2, 2, 3]) # Converts list to set (removes duplicates) dict_val = dict([(1, 'one'), (2, 'two')]) # Converts list of tuples to dictionary 

• int(x): Converts x to an integer.
• float(x): Converts x to a floating-point number.
• str(x): Converts x to a string.
• bool(x): Converts x to a boolean (True or False).
• list(iterable): Converts an iterable to a list.
• tuple(iterable): Converts an iterable to a tuple.
• set(iterable): Converts an iterable to a set.
• dict(iterable): Converts an iterable to a dictionary.

2. Mathematical Functions

Python offers built-in math functions to perform calculations.

print(abs(-10)) # Output: 10 print(pow(2, 3)) # Output: 8 (2^3) print(round(3.14159, 2)) # Output: 3.14 print(max(1, 2, 3)) # Output: 3 print(min(1, 2, 3)) # Output: 1 print(sum([1, 2, 3])) # Output: 6 print(divmod(10, 3)) # Output: (3, 1) (quotient and remainder) 

• abs(x): Returns the absolute value of x.
• pow(x, y): Computes x raised to the power y.
• round(x, n): Rounds x to n decimal places.
• max(iterable): Returns the largest item in an iterable.
• min(iterable): Returns the smallest item in an iterable.
• sum(iterable): Returns the sum of all items in an iterable.
• divmod(x, y): Returns a tuple of quotient and remainder.

3. Iterables and Sequences

Functions that help manipulate sequences like lists and tuples.

numbers = [1, 2, 3, 4] print(len(numbers)) # Output: 4 print(sorted(numbers, reverse=True)) # Output: [4, 3, 2, 1] print(list(reversed(numbers))) # Output: [4, 3, 2, 1] print(list(enumerate(numbers))) # Output: [(0, 1), (1, 2), (2, 3), (3, 4)] print(list(zip([1, 2], ['a', 'b']))) # Output: [(1, 'a'), (2, 'b')] 

• len(s): Returns the length of s.
• sorted(iterable, key=None, reverse=False): Returns a sorted list.
• reversed(iterable): Returns a reversed iterator.
• enumerate(iterable, start=0): Returns index-value pairs.
• zip(*iterables): Combines multiple iterables into tuples.

4. Input and Output

Handling user input and displaying output.

name = input("Enter your name: ") print(f"Hello, {name}!") with open("file.txt", "w") as file: file.write("Hello, World!") with open("file.txt", "r") as file: print(file.read()) # Output: Hello, World! 

• print(*objects): Prints objects to output.
• input(prompt): Gets user input as a string.
• open(file, mode): Opens a file for reading or writing.

5. Object and Type Checking

Verify types and attributes of objects.

print(isinstance(100, int)) # Output: True print(type("hello")) # Output: <class 'str'> print(issubclass(int, object)) # Output: True print(callable(len)) # Output: True 

• type(object): Returns the type of an object.
• isinstance(object, classinfo): Checks if an object is an instance of a class.
• issubclass(class, classinfo): Checks if a class is a subclass of another.
• callable(object): Checks if an object is callable (e.g., a function).

6. Memory and Object Management

Functions for handling object attributes and memory.

class Car: def __init__(self, brand): self.brand = brand car = Car("Toyota") print(getattr(car, "brand")) # Output: Toyota setattr(car, "brand", "Honda") print(hasattr(car, "brand")) # Output: True delattr(car, "brand") print(hasattr(car, "brand")) # Output: False 

• getattr(obj, name): Gets an attribute value.
• setattr(obj, name, value): Sets an attribute.
• hasattr(obj, name): Checks if an attribute exists.
• delattr(obj, name): Deletes an attribute.

7. Functional Programming

Useful functions for functional-style programming.

nums = [0, 1, 2, 3] print(all(nums)) # Output: False print(any(nums)) # Output: True print(list(filter(lambda x: x > 1, nums))) # Output: [2, 3] print(list(map(lambda x: x * 2, nums))) # Output: [0, 2, 4, 6] 

• all(iterable): Returns True if all elements are True.
• any(iterable): Returns True if any element is True.
• filter(function, iterable): Filters elements based on a function.
• map(function, iterable): Applies a function to all elements.

8. Other Useful Functions

Miscellaneous functions for various tasks.

print(bin(10)) # Output: '0b101' print(hex(255)) # Output: '0xff' print(ord('A')) # Output: 65 print(chr(65)) # Output: 'A' 

Conclusion

Happy coding! 🚀