20 Extremely Useful Single-Line Python Codes
Enes ARSLAN
Posted on March 6, 2023
1.One-line For Loop
For loops are multi-line statements, but in Python, we can write for loops in one line using list comprehension methods. As an example, to filter out values less than 250, take a look at the following code example.
#For loop in one line
mylist = [200, 300, 400, 500]
#Single line For loop
result = []
for x in mylist:
if x > 250:
result.append(x)
print(result) # [300, 400, 500]
#One-line code way
result = [x for x in mylist if x > 250]
print(result) # [300, 400, 500]
2 .One-Line While Loop
This One-Liner segment will show you how to use While loop code in one line, with two different methods demonstrated.
#Method 1 Single Statement
while True: print(1) #infinite 1
#Method 2 Multiple Statements
x = 0
while x < 5: print(x); x= x + 1 # 0 1 2 3 4 5
3 .One-Line IF Else Statement
Alright, to write an IF Else statement in one line we will use the ternary operator. The syntax for the ternary is “[on true] if [expression] else [on false]”.
I have shown 3 examples in the sample code below to make it clear to you on how to use the ternary operator for a one-line if-else statement. To use an Elif statement, we must use multiple ternary operators.
#if Else In a single line.
#Example 1 if else
print("Yes") if 8 > 9 else print("No") # No
#Example 2 if elif else
E = 2
print("High") if E == 5 else print("数据STUDIO") if E == 2 else
print("Low") # Data STUDIO
#Example 3 only if
if 3 > 2: print("Exactly") # Exactly
4.Merging dictionaries in one line
This one-liner code segment will show you how to merge two dictionaries into one using a single line of code. Here, I’ve presented two methods for merging dictionaries.
# Merging dictionaries in one line
d1 = { 'A': 1, 'B': 2 }
d2 = { 'C': 3, 'D': 4 }
#Method1
d1.update(d2)
print(d1) # {'A': 1, 'B': 2, 'C': 3, 'D': 4}
#Method2
d3 = {**d1, **d2}
print(d3) # {'A': 1, 'B': 2, 'C': 3, 'D': 4}
5. One-Line Function
There are two ways we can write a function in one line, in the first method we will use the same function definition as with the ternary operator or one-line loop method.
The second method is to use lambda to define the function. Take a look at the example code below for a clearer understanding.
#Function in one line
#Method1
def fun(x): return True if x % 2 == 0 else False
print(fun(2)) # False
#Method2
fun = lambda x : x % 2 == 0
print(fun(2)) # True
print(fun(3)) # False
6.Recursion in one line
This single-line code snippet will show you how to use recursion in one line. We will use a one-line function definition and a one-line if-else statement. Here is an example for finding the Fibonacci numbers.
# Single-line recursion
#Fibonaci Single-line recursion example
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
7.Filtering an array in one line
Filtering an array in one line of code using Python lists can be done using the list comprehension method. An example of filtering an even number list is shown.
# Filtering arrays in a single line
mylist = [2, 3, 5, 8, 9, 12, 13, 15]
#Normal way
result = []
for x in mylist:
if x % 2 == 0:
result.append(x)
print(result) # [2, 8, 12]
# One-line method
result = [x for x in mylist if x % 2 == 0]
print(result) # [2, 8, 12]
8.Exception Handling in One Line
We use exception handling to handle runtime errors in Python. Did you know that we can write the Try except statement in one line? By using the exec() statement, we can do this.
# Exception handling in one line
#Original method
try:
print(x)
except:
print("Error")
#Single line way
exec('try:print(x) \nexcept:print("Error")') # Error
9.Converting a list to a dictionary in one line
Convert a list to a dictionary in one line using the Python enumerate() function. Pass the list to enumerate() and use dict() to convert the final output to dictionary format.
# Dictionary in one line
mydict = ["John", "Peter", "Mathew", "Tom"]
mydict = dict(enumerate(mydict))
print(mydict) # {0: 'John', 1: 'Peter', 2: 'Mathew', 3: 'Tom'}
10.One-Line Multiple Variables
Python allows for multiple variable assignments in one line. The following example code will show you how to do this.
#Multiple variable assignments in one line.
#Single-line method
x = 5
y = 7
z = 10
print(x , y, z) # 5 7 10
#Single line way
a, b, c = 5, 7, 10
print(a, b, c) # 5 7 10
11.Swapping values in one line
In one line, exchange values. Swapping is a fun task in programming, and it always requires a third variable name, temp, to save the swapped value. This one-line code snippet will show you how to swap values in one line without any temporary variables.
#Swap values in one line
#Single-line method
v1 = 100
v2 = 200
temp = v1
v1 = v2
v2 = temp
print(v1, v2) # 200 100
# One-line value swapping
v1, v2 = v2, v1
print(v1, v2) # 200 100
12.One-Line Sorting
Sorting is a common problem in programming, and Python has many built-in methods to solve this sorting problem. The code examples below will show how to sort in one line.
# Sort in one line
mylist = [32, 22, 11, 4, 6, 8, 12]
# Method1
mylist.sort()
print(mylist) # # [4, 6, 8, 11, 12, 22, 32]
print(sorted(mylist)) # [4, 6, 8, 11, 12, 22, 32]
13.Reading a file in one line
You can correctly read a line of a file without using statements or the normal reading methods.
#Reading a file in one line
#Single-line method
with open("data.txt", "r") as file:
data = file.readline()
print(data) # Hello world
#Single line way
data = [line.strip() for line in open("data.txt","r")]
print(data) # ['hello world', 'Hello Python']
14.One-line class
Classes are always multi-line work. But in Python, there are ways to use class features in one line of code.
# One-line class
#Regular way
class Emp:
def __init__(self, name, age):
self.name = name
self.age = age
emp1 = Emp("a44", 22)
print(emp1.name, emp1.age) #
#Single line way
#Method 1 Lambda with Dynamic Attributes
Emp = lambda:None; Emp.name = "a44"; Emp.age = 22
print(Emp.name, Emp.age) #
#Method 2
from collections import namedtuple
Emp = namedtuple('Emp', ["name", "age"]) ("a44", 22)
print(Emp.name, Emp.age)
15.One-line semicolon
In this code snippet, the semicolon shows you how to use a semicolon to write multiple lines of code in a single line.
python
# One-line semicolon
# exsample 1
a = "Python"; b = "Programming"; c = "languages"; print(a, b, c)
# print
# Python Programming languages
16.One line print
This isn’t an important snippet, but it can be useful sometimes when you don’t need to use a loop to perform a task.
# One line print
#Single-line method
for x in range(1, 5):
print(x) # 1 2 3 4
#Single line way
print(*range(1, 5)) # 1 2 3 4
print(*range(1, 6)) # 1 2 3 4 5
17.One line map function
The map function is a useful higher-order function that applies a function to each element. Here is an example of how we can use the map function in one line of code.
#One line map function
print(list(map(lambda a: a + 2, [5, 6, 7, 8, 9, 10])))
# print
# [7, 8, 9, 10, 11, 12]
18.Deleting the Mul elements from the first row of the list
You can now use the del method to delete multiple elements from a List in a single line of code, without any modification.
# Deleting the Mul elements from the first row of the list
mylist = [100, 200, 300, 400, 500]
del mylist[1::2]
print(mylist) # [100, 300, 500]
19.One line print pattern
Now you no longer need to use a for loop to print the same pattern. You can use the print statement and asterisk (*) to do the same thing in a single line of code.
# One line print pattern#
# Single-line method
for x in range(3):
print('😀')
# print
# 😀 😀 😀
#Single line way
print('😀' * 3) # 😀 😀 😀
print('😀' * 2) # 😀 😀
print('😀' * 1) # 😀
20.Find primes in a range in a single line of code
This code snippet will show you how to write a single line of code to find the prime numbers within a range.
# Find primes in a range in a single line of code
print(list(filter(lambda a: all(a % b != 0 for b in range(2, a)),
range(2,20))))
# print
# [2, 3, 5, 7, 11, 13, 17, 19]
Posted on March 6, 2023
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