20 Useful Python One‑Liner Code Snippets

This article shares a collection of 20 useful Python one‑liner snippets that demonstrate how to accomplish common tasks in a single line of code, making scripts shorter and more readable.

1. One‑line For Loop

Use a list comprehension to filter values greater than 250 in one line.

<code># For loop in one line
mylist = [200, 300, 400, 500]
# normal way
result = []
for x in mylist:
    if x > 250:
        result.append(x)
print(result)  # [300, 400, 500]
# one‑line way
result = [x for x in mylist if x > 250]
print(result)  # [300, 400, 500]</code>

2. One‑line While Loop

Two approaches to write a while loop in a single line.

<code># Method 1 Single Statement
while True: print(1)  # infinite 1
# Method 2 multi‑statement
x = 0
while x < 5: print(x); x = x + 1  # 0 1 2 3 4</code>

3. One‑line If‑Else

Use the ternary operator to place an if‑else expression on one line.

<code># if‑else in one line
print("Yes") if 8 > 9 else print("No")  # No
E = 2
print("High") if E == 5 else print("DataSTUDIO") if E == 2 else print("Low")  # DataSTUDIO
if 3 > 2: print("Exactly")  # Exactly</code>

4. One‑line Dictionary Merge

Combine two dictionaries using either update() or dictionary unpacking.

<code># merge dictionaries in one line
d1 = {'A': 1, 'B': 2}
d2 = {'C': 3, 'D': 4}
# method 1
d1.update(d2)
print(d1)  # {'A': 1, 'B': 2, 'C': 3, 'D': 4}
# method 2
d3 = {**d1, **d2}
print(d3)  # {'A': 1, 'B': 2, 'C': 3, 'D': 4}</code>

5. One‑line Function

Define a function with a conditional return or use a lambda expression.

<code># function in one line
# method 1
def fun(x): return True if x % 2 == 0 else False
print(fun(2))  # False
# method 2
fun = lambda x: x % 2 == 0
print(fun(2))  # True
print(fun(3))  # False</code>

6. One‑line Recursion

Calculate Fibonacci numbers with a recursive one‑liner.

<code># one‑line recursion
def Fib(x): return 1 if x in {0, 1} else Fib(x-1) + Fib(x-2)
print(Fib(5))  # 8
print(Fib(15))  # 987</code>

7. One‑line List Filtering

Filter even numbers from a list using a list comprehension.

<code># list filtering in one line
mylist = [2, 3, 5, 8, 9, 12, 13, 15]
result = [x for x in mylist if x % 2 == 0]
print(result)  # [2, 8, 12]</code>

8. One‑line Exception Handling

Wrap a try‑except block inside an exec() call.

<code># one‑line exception handling
try:
    print(x)
except:
    print("Error")
# one‑line way
exec('try:print(x) \nexcept:print("Error")')</code>

9. One‑line List to Dictionary

Convert a list to a dictionary using enumerate() in a single line.

<code># list to dict in one line
mylist = ["John", "Peter", "Mathew", "Tom"]
mydict = dict(enumerate(mylist))
print(mydict)  # {0: 'John', 1: 'Peter', 2: 'Mathew', 3: 'Tom'}</code>

10. One‑line Multiple Assignment

Assign several variables at once.

<code># multiple variables
a, b, c = 5, 7, 10
print(a, b, c)  # 5 7 10</code>

11. One‑line Value Swap

Swap two variables without a temporary variable.

<code># swap in one line
v1, v2 = 100, 200
v1, v2 = v2, v1
print(v1, v2)  # 200 100</code>

12. One‑line Sorting

Sort a list using the sort() method or the sorted() function.

<code># sort in one line
mylist = [32, 22, 11, 4, 6, 8, 12]
mylist.sort()
print(mylist)  # [4, 6, 8, 11, 12, 22, 32]
print(sorted(mylist))  # [4, 6, 8, 11, 12, 22, 32]</code>

13. One‑line File Reading

Read a file into a list with a single comprehension.

<code># read file in one line
data = [line.strip() for line in open("data.txt", "r")]
print(data)  # ['hello world', 'Hello Python']</code>

14. One‑line Class

Define a simple class or use namedtuple in a single line.

<code># class in one line
Emp = lambda: None; Emp.name = "云朵君"; Emp.age = 22
print(Emp.name, Emp.age)  # 云朵君 22
from collections import namedtuple
Emp = namedtuple('Emp', ['name', 'age'])('云朵君', 22)
print(Emp.name, Emp.age)  # 云朵君 22</code>

15. One‑line Semicolon

Separate multiple statements on a single line using semicolons.

<code># one‑line with semicolons
a = "Python"; b = "编程"; c = "语言"; print(a, b, c)  # Python 编程 语言</code>

16. One‑line Print

Print a range of numbers without an explicit loop.

<code># one‑line print
print(*range(1, 5))  # 1 2 3 4
print(*range(1, 6))  # 1 2 3 4 5</code>

17. One‑line map Function

Apply a lambda to each element of a list using map.

<code># map in one line
print(list(map(lambda a: a + 2, [5, 6, 7, 8, 9, 10])))  # [7, 8, 9, 10, 11, 12]</code>

18. One‑line Delete Multiple List Elements

Remove every second element from a list using slice deletion.

<code># delete multiple elements in one line
mylist = [100, 200, 300, 400, 500]
del mylist[1::2]
print(mylist)  # [100, 300, 500]</code>

19. One‑line Pattern Printing

Print repeated characters without a loop.

<code># print pattern in one line
print('😀' * 3)  # 😀😀😀
print('😀' * 2)  # 😀😀
print('😀' * 1)  # 😀</code>

20. One‑line Prime Finder

Generate a list of prime numbers within a range using filter and lambda.

<code># find primes in one line
print(list(filter(lambda a: all(a % b != 0 for b in range(2, a)), range(2, 20))))
# [2, 3, 5, 7, 11, 13, 17, 19]</code>

These snippets illustrate how Python’s expressive syntax can condense common programming patterns into concise one‑liners, helping developers write more compact and maintainable code.