100 Python One-Liners Everyone Should Know
Master the art of concise, elegant Python with these brilliant one-liners — from basic tricks to powerful expressions every developer…
Think Python is powerful? Wait until you see what it can do in just one line.
100 Python One-Liners Everyone Should Know
Master the art of concise, elegant Python with these brilliant one-liners — from basic tricks to powerful expressions every developer should know.
Whether you’re a seasoned Pythonista or a curious coder aiming to sharpen your skills, there’s something deeply satisfying about writing clean, expressive code in a single line.
Python’s elegant syntax and functional capabilities make it perfect for writing powerful one-liners. These aren’t just gimmicks — they’re practical, time-saving tricks that demonstrate the language’s flexibility.
In this article, we’ll explore 100 Python one-liners across categories like strings, lists, dictionaries, file handling, and even basic algorithms — all written to help you code smarter, not harder.
Writing one-liners isn’t just about showing off (although it does feel good). It’s about learning:
How to think functionally
How to chain built-ins and write clean expressions
How to simplify everyday problems
And yes — how to make your code look cool in reviews
Let’s dive into 50 Python one-liners that belong in your mental toolbox.
String Tricks
# 1. Reverse a string
"hello"[::-1]
# 2. Check for palindrome
lambda s: s == s[::-1]
# 3. Count vowels
sum(1 for c in "hello world" if c in "aeiou")
# 4. Remove duplicates
"".join(dict.fromkeys("aabbcc"))
# 5. Most frequent character
from collections import Counter; Counter("banana").most_common(1)[0][0]
# 6. Convert to title case
"this is title".title()
# 7. Check if all characters are digits
"12345".isdigit()
# 8. Replace vowels with '*'
"hello world".translate(str.maketrans("aeiou", "*****"))
# 9. Count words
len("How many words?".split())
# 10. Remove punctuation
import string; ''.join(c for c in "hello, world!" if c not in string.punctuation)Number and Math Magic
# 11. Prime check
lambda x: x > 1 and all(x % i for i in range(2, int(x**0.5)+1))
# 12. Fibonacci (first 10)
fib = [0, 1]; [fib.append(fib[-1]+fib[-2]) for _ in range(8)]
# 13. Sum of digits
sum(map(int, str(1234)))
# 14. Factorial
from math import factorial; factorial(5)
# 15. GCD
from math import gcd; gcd(24, 36)
# 16. LCM
lambda a, b: abs(a*b) // gcd(a, b)
# 17. Round to 2 decimals
round(3.14159, 2)
# 18. Binary of a number
bin(42)[2:]
# 19. Convert binary to int
int("101010", 2)
# 20. Square root
import math; math.sqrt(16)List Manipulations
# 21. Flatten nested lists
[i for sub in [[1,2],[3,4]] for i in sub]
# 22. Unique elements
list(set([1,2,2,3]))
# 23. Sort by second value
sorted([(1,3),(2,2),(3,1)], key=lambda x: x[1])
# 24. Intersection
list(set([1,2,3]) & set([2,3,4]))
# 25. Evens
[x for x in range(10) if x % 2 == 0]
# 26. Remove falsy values
list(filter(bool, [0, 1, '', 'hello', None]))
# 27. List of dictionaries
[{'id': i} for i in range(3)]
# 28. List of even squares
[x**2 for x in range(10) if x%2==0]
# 29. Find duplicates
[x for x in [1,2,2,3] if [1,2,2,3].count(x) > 1]
# 30. Chunk list
[ [1,2,3,4][i:i+2] for i in range(0, 4, 2) ]Loops & Comprehensions
# 31. Squares
[x**2 for x in range(10)]
# 32. Filter positives
list(filter(lambda x: x > 0, [-2, 3, 0, 1]))
# 33. Flatten dict values
[v for values in {'a': [1,2], 'b': [3]}.values() for v in values]
# 34. Zip lists
list(zip([1,2], ['a','b']))
# 35. Cartesian product
[(x, y) for x in [1,2] for y in [3,4]]
# 36. Nested list comprehension
[[i*j for j in range(1, 4)] for i in range(1, 4)]
# 37. Reverse list
[1,2,3][::-1]
# 38. Enumerate list
list(enumerate(['a', 'b', 'c']))
# 39. Combine multiple lists
[x+y for x, y in zip([1,2], [3,4])]
# 40. Filter with list comprehension
[x for x in range(10) if x % 3 == 0]Dictionary Hacks
# 41. Invert dict
{v:k for k,v in {'a':1,'b':2}.items()}
# 42. Merge two dicts
{**{'a':1}, **{'b':2}}
# 43. Count frequency
{x: [1,2,2,3].count(x) for x in set([1,2,2,3])}
# 44. Dict from two lists
dict(zip(['a','b'], [1,2]))
# 45. Defaultdict grouping
from collections import defaultdict; d=defaultdict(list); [d[len(s)].append(s) for s in ['hi','hello','hey']]
# 46. Dict comprehension with condition
{x: x**2 for x in range(5) if x%2 == 0}
# 47. Sort dict by values
dict(sorted({'a':3,'b':1}.items(), key=lambda item: item[1]))
# 48. Nested dict
{'outer': {'inner': 42}}
# 49. Access safely
d.get('missing', 'default')
# 50. Swap keys and values
dict(map(reversed, {'a':1,'b':2}.items()))File Handling & I/O
# 51. Read lines
open("file.txt").read().splitlines()
# 52. Word count
len(open("file.txt").read().split())
# 53. Write list to file
open("out.txt", "w").writelines([f"{i}\n" for i in range(5)])
# 54. File size
import os; os.path.getsize("file.txt")
# 55. Check file exists
os.path.exists("file.txt")
# 56. Count specific word
open("file.txt").read().count("Python")
# 57. Read last line
open("file.txt").readlines()[-1]
# 58. Read first 100 characters
open("file.txt").read(100)
# 59. Get file extension
os.path.splitext("file.txt")[1]
# 60. Count lines
sum(1 for _ in open("file.txt"))Searching and Filtering
# 61. First even number
next(x for x in [1,3,5,6] if x%2==0)
# 62. Any true?
any([0, False, 1])
# 63. All positive?
all(x > 0 for x in [1, 2, 3])
# 64. Index of item
[1,2,3].index(2)
# 65. Most frequent
max(set([1,1,2]), key=[1,1,2].count)
# 66. Find longest string
max(["hi", "hello", "world"], key=len)
# 67. Filter None
list(filter(None, [0, "", None, 5]))
# 68. Count even numbers
sum(1 for x in range(10) if x%2 == 0)
# 69. First negative number
next((x for x in [-1, 0, 1] if x < 0), None)
# 70. Filter by type
[x for x in [1, "two", 3.0] if isinstance(x, int)]Utility Patterns
# 71. Swap
a, b = b, a
# 72. Ternary
"Yes" if x > 0 else "No"
# 73. Chain comparisons
5 < x < 10
# 74. CSV string
",".join(map(str, [1,2,3]))
# 75. Timer
import time; start=time.time(); time.sleep(1); print(time.time()-start)
# 76. Assert in one line
assert x > 0, "x must be positive"
# 77. Retry logic
any(f(x) for _ in range(3))
# 78. Range as list
list(range(5))
# 79. Current timestamp
import time; time.time()
# 80. Generate UUID
import uuid; str(uuid.uuid4())Functions & Lambdas
# 81. Lambda square
lambda x: x**2
# 82. Compose
f = lambda x: x+1; g = lambda x: x*2; compose = lambda x: f(g(x))
# 83. Map uppercase
list(map(str.upper, ['a','b','c']))
# 84. Filter empty strings
list(filter(None, ["", "hi", ""]))
# 85. Recursive factorial
lambda n: 1 if n==0 else n*factorial(n-1)
# 86. Function call timing
(lambda f: (time.time(), f(), time.time()))(lambda: sum(range(10**6)))
# 87. Inline function call
(lambda x: x**2)(4)
# 88. Conditional lambda
(lambda x: "even" if x%2==0 else "odd")(5)
# 89. Sum lambda
sum(map(lambda x: x+1, range(5)))
# 90. Dict of lambdas
ops = {'add': lambda x, y: x+y, 'mul': lambda x, y: x*y}Miscellaneous One-Liners
# 91. Python version
import sys; sys.version.split()[0]
# 92. Convert list to int
int("".join(map(str, [1,2,3])))
# 93. Shuffle list
import random; random.shuffle(lst)
# 94. Reverse dict
dict(reversed(list(d.items())))
# 95. Random choice
random.choice([1,2,3])
# 96. Regex match
import re; bool(re.match(r"\d+", "123abc"))
# 97. List to set to list
list(set([1,2,2,3]))
# 98. Terminal progress bar
print(f"\rProgress: [{'='*x}>{' '*(10-x)}]", end='')
# 99. Get memory size
import sys; sys.getsizeof([1,2,3])
# 100. One-liner HTTP server
# Terminal: python -m http.server 8000Final Thoughts
Python one-liners aren’t just clever — they’re a testament to the elegance and power of the language. Learning to write concise code makes you a better problem solver and forces you to think in terms of composition, transformation, and readability.
Try sprinkling these into your projects or during code challenges. You’ll not only save time — you’ll impress your peers and sharpen your Pythonic thinking.
What’s Your Favorite One-Liner?
Share it in the comments or bookmark this list for your future projects!
Because in Python, less truly is more.
