50 Most Commonly Used Python Code Snippets for Everyday Programming

50 Most Commonly Used Python Code Snippets for Everyday Programming

Summary

Learn essential Python code snippets for everyday programming, covering list operations, file handling, string manipulation, mathematical operations, data structures, conditionals, loops, utilities, modules, and advanced techniques. Discover how to perform tasks such as list comprehension, file reading and writing, string reversal, and data type checking. Explore snippets for calculating factorials, generating Fibonacci sequences, and working with dictionaries. Master useful functions like lambda, map, filter, and reduce, and improve your Python programming skills with these 50 commonly used code snippets.

Python, owing to its simplicity and expressiveness, remains one of the most loved programming languages in the world. Whether you are a beginner or a seasoned developer, having a handy set of frequently used code snippets can save considerable time. This article presents 50 widely used Python code snippets, categorised for clarity and practical use.


πŸ” List Operations

1. List Comprehension with Condition

squares = [x**2 for x in range(10) if x % 2 == 0]

2. Flatten a Nested List

nested = [[1, 2], [3, 4]]
flat = [item for sublist in nested for item in sublist]

3. Remove Duplicates from a List

unique_items = list(set(my_list))

4. Reverse a List

reversed_list = my_list[::-1]

5. Sort List of Dictionaries by Key

sorted_list = sorted(dicts_list, key=lambda x: x['key_name'])


πŸ“ File Handling

6. Read a File

with open('file.txt', 'r') as file:
    content = file.read()

7. Write to a File

with open('file.txt', 'w') as file:
    file.write('Hello, World!')

8. Append to a File

with open('file.txt', 'a') as file:
    file.write('\nAppended line.')

9. Read a File Line by Line

with open('file.txt', 'r') as file:
    for line in file:
        print(line.strip())

10. Check if File Exists

import os
exists = os.path.isfile('file.txt')


πŸ” String Manipulation

11. Reverse a String

reversed_str = my_string[::-1]

12. Check for Palindrome

is_palindrome = my_string == my_string[::-1]

13. Count Occurrences of a Substring

count = my_string.count('substring')

14. Replace Substring

new_string = my_string.replace('old', 'new')

15. Split String into List

words = my_string.split()


πŸ“ Mathematical Operations

16. Calculate Factorial

import math
result = math.factorial(5)

17. Generate Fibonacci Sequence

def fibonacci(n):
    a, b = 0, 1
    for _ in range(n):
        yield a
        a, b = b, a + b

18. Check for Prime Number

def is_prime(n):
    return n > 1 and all(n % i for i in range(2, int(n**0.5) + 1))

19. Find GCD of Two Numbers

import math
gcd = math.gcd(a, b)

20. Calculate Square Root

import math
sqrt = math.sqrt(16)


πŸ“Š Data Structures

21. Merge Two Dictionaries

merged_dict = {**dict1, **dict2}

22. Invert a Dictionary

inverted = {v: k for k, v in original.items()}

23. Create Dictionary from Two Lists

dict_from_lists = dict(zip(keys, values))

24. Count Frequency of Elements

from collections import Counter
freq = Counter(my_list)

25. Sort Dictionary by Value

sorted_dict = dict(sorted(my_dict.items(), key=lambda item: item[1]))


πŸ§ͺ Conditionals and Loops

26. Ternary Conditional Operator

result = 'Yes' if condition else 'No'

27. Enumerate in Loop

for index, value in enumerate(my_list):
    print(index, value)

28. Zip Multiple Lists

for a, b in zip(list1, list2):
    print(a, b)

29. List Comprehension with Multiple Conditions

result = [x for x in range(100) if x % 2 == 0 and x % 5 == 0]

30. Nested Loops in List Comprehension

pairs = [(x, y) for x in list1 for y in list2]


πŸ› οΈ Utilities

31. Measure Execution Time

import time
start = time.time()
# code block
end = time.time()
print(f"Execution Time: {end - start}")

32. Shuffle a List

import random
random.shuffle(my_list)

33. Generate Random Number

import random
num = random.randint(1, 100)

34. Check if List is Empty

if not my_list:
    print("List is empty")

35. Swap Two Variables

a, b = b, a


πŸ“¦ Modules and Packages

36. Install Package via pip

pip install package_name

37. Import Module with Alias

import numpy as np

38. Handle Import Errors

try:
    import module
except ImportError:
    # handle error

39. List Installed Packages

pip list

40. Get Current Working Directory

import os
cwd = os.getcwd()


🧰 Advanced Techniques

41. Lambda Function

square = lambda x: x * x

42. Map Function

squares = list(map(lambda x: x**2, my_list))

43. Filter Function

evens = list(filter(lambda x: x % 2 == 0, my_list))

44. Reduce Function

from functools import reduce
product = reduce((lambda x, y: x * y), my_list)

45. List All Attributes of an Object

attributes = dir(object)


πŸ—’οΈ Miscellaneous

46. Check Data Type

type_of_var = type(variable)

47. Convert String to Integer

num = int('123')

48. Convert Integer to String

s = str(123)

49. Format String with f-Strings

name = 'Alice'
greeting = f'Hello, {name}!'

50. Use of Any and All

any_true = any([False, True, False])
all_true = all([True, True, True])


These code snippets are practical, often used in day-to-day tasks, and should be part of every Python developer's toolkit. Feel free to bookmark or adapt them to your projects.