🐍💻 Practical Python One-Liners: Short, Sweet, and Powerful!

🐍👨‍💻 Today, we will explore some practical Python one-liners. Is it possible to write a single-line Python code? Shortening the code, making it cleaner? Yes! But it can be challenging for beginners. Let’s see some examples:

1. One-liner loop

Let’s begin by creating a list of integers from 0 to 10 using a loop

Normal Program

num_list=[]
for num in range(0, 11):
   num_list.append(num)
print(num_list)
>>> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

One-liner Program

num_list=[for num in range(0, 10+1)]
## '10+1' as the upper limit is excluded.
print(num_list)
>>> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

2. For loop with ‘if’ statement

With the help of a for-loop and an if statement inside of a list , we are here producing a list that only includes even integers.

Normal Program

even_num_list =[]
for num in range(10, 20):
   if num % 2 == 0:
      even_num_list.append(num)
print(even_num_list)
>>> [10, 12, 14, 16, 18]

One-liner Program

even_num_list=[num for num in range(10, 20) if num % 2 == 0]
print(even_num_list)
>>> [10, 12, 14, 16, 18]

3. if-else statements

Problem statement:
If the age of a boy/girl is less than 18 then he/she is Minor then we need to print: “You are a Minor” or else they are an Adult and we need to print: “You are an Adult”

Normal Program

age = 12
if age > 18:
   print("You are an Adult")
else:
   print("You are a Minor")
>>> You are a Minor

One-liner Program

result= "You are an Adult" if age > 18 else "You are a Minor"
print(result)
>>> You are a Minor

4. for loop with if-else statement

Problem statement:
If the number is even, replace it with ‘*’ or else, replace it with ‘#’.

Normal Program

num_list=[2,4,8,11,45,23,10]
even_num_count = 0
for num in num_list:
   if num % 2 == 0:
      num_list[num_list.index(num)] = '*'
   else:
      num_list[num_list.index(num)] = '#'
print(num_list)
>>> ['*', '*', '*', '#', '#', '#', '*']

One-liner Program

num_list=[2,4,8,11,45,23,10]
print(['*' if num%2==0 else '#' for num in num_list])
>>> ['*', '*', '*', '#', '#', '#', '*']

5. Double for loop

Here we are appending multiple tuples inside a list using nested for-loop.

Normal Program

num_list = []
for num1 in range(1, 3):
     for num2 in range(1, 4):
          num_list.append((num1 ,num2))
print(num_list)
>>> [(1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3)]

One-liner Program

result=[(num1,num2) for num1 in range(1, 3) for num2 in range(1, 4)]
print(result)
>>> [(1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3)]

6. Multiple assignments

Here we are assigning multiple values to multiple variables.

Normal Program

a=1
b=2.5
c=6
print("a: {}, b: {}, c: {}".format(a,b,c))
>>> a: 1, b: 2.5, c: 6

One-liner Program

a,b,c = 1, 2.5, 6
print("a: {}, b: {}, c: {}".format(a,b,c))
>>> a: 1, b: 2.5, c: 6

Here we are assigning multiple values to multiple variables.

a, b, *c =[1,2,3,4,5,6,7]
print("a: {}, b: {}, c: {}".format(a,b,c))
>>> a: 1, b: 2, c: [3, 4, 5, 6, 7]

7. Swapping two numbers

a, b = 5, 9
a, b = b, a

8. Reading Files

Here we are just reading a text file.

lst = [line.strip() for line in open('data.txt')]
print(lst)

9. Lambda Function

What exactly is a lambda function?
a. Small anonymous functions are called lambda functions.
b. A lambda function can have one expression but any number of arguments.

Here we are calculating the square of a number.

num_sqr=lambda x: x**2
num_sqr(10)
>>> 100

Here we are multiplying two numbers using the lambda function

multiple_two_nums = lambda x,y: x * y
multiple_two_nums(10,20)>>> 200

Here we are filtering odd numbers from a list using the filter function

nums = [34, 23, 56, 89, 44, 92]
odds = list(filter(lambda x: x % 2 != 0, nums))
print(odds)>>> [23, 89]

filter()

• The filter() function takes two arguments:

a. function — a function

b. iterable — (sets, lists, tuples, etc.)

• The function returns an iterator where the items are filtered through a function to test if the item is accepted or not.

def filter_odd_number(number):
    if number % 2==1:
        return True
    else: 
        return False 
for num in filter(filter_odd_number, [7,5,6,7,8]):print(num)
>>>
7
5
7

10. TypeCasting Whole List

string_list = ['1','2','3','4','5','6']
int_list = list(map(int, string_list))
>>> [1, 2, 3, 4, 5, 6]
-------------------------------or--------------------------------int_list = [int(i) for i in string_list]
>>> [1, 2, 3, 4, 5, 6]
float_list = list(map(float, int_list))
>>> [1.0, 2.0, 3.0, 4.0, 5.0, 6.0]
-------------------------------or---------------------------------
float_list = [float(i) for i in int_list]
>>> [1.0, 2.0, 3.0, 4.0, 5.0, 6.0]

map() function

the function takes two parameters:

• function — a function that performs some action to each element of an iterable
• iterable — a collection of variables/items such as sets, lists, tuples, etc

Here we are just typecasting from one to another using the map function

Reference:

1. https://wiki.python.org/moin/Powerful%20Python%20One-Liners
2. https://www.python.org/

Thank you for reading. If you find something wrong or better ways to do it, let me know in the comments below.

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