BrendahKiragu

Posted on Mar 3

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.

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! 🚀

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