Artturi Jalli's Blog

Artturi Jalli's Blog

10 Useful Python Coding Tricks

10 Useful Python Coding Tricks

Here is a list of useful tips and "tricks" I love to use with Python. Learn these and impress your friends and colleagues.

This list is in no particular order.

1. Swap Two Variables With One Line of Code

Can you think of a way to swap two variables without a third? Well, here it is:

a = 1
b = 2
a, b = b, a

2. Duplicate Strings Without Looping

name = "Banana"
print(name * 4)



3. Reverse a String

sentence = "This is just a test"
reversed = sentence[::-1]


tset a tsuj si sihT

4. Squash a List of Strings Into One String

words = ["This", "is", "a", "Test"]
combined = " ".join(words)


This is a Test

5. Comparison Chains

You can combine comparisons together instead of splitting the statement into two or more parts. This works just like you write maths. For example:

x = 100
res = 0 < x < 1000



6. Find the Most Frequent Element in a List

test = [6, 2, 2, 3, 4, 2, 2, 90, 2, 41]
most_frequent = max(set(test), key = test.count)



7. Unpack List to Separate Variables

You can unpack a list of elements to variables. Just keep the number of variables the same as the number of list elements.

For instance:

arr = [1, 2, 3]
a,b,c = arr
print(a, b, c)


1 2 3

8. One-Liner If-Else Statements

You can compress your code by writing some simple if-else's as one-liners. In Python, one-liner if-else statements are called conditional operators. For example:

age = 30
age_group = "Adult" if age > 18 else "Child"



For your convenience, here is the pattern for using the conditional operator:

true_expression if condition else false_expression

9. Loop Through a List With One Line of Code

You can use comprehensions to loop through a list with one line of code. For example, let's raise each number in a list to the second power:

numbers = [1, 2, 3, 4, 5]
squared_numbers = [num * num for num in numbers]


[1, 4, 9, 16, 25]

Note: Comprehensions are not just limited to working with lists. You can use comprehensions in a similar one-liner fashion with dictionaries, sets, and generators as well.

Let's see another example by using dictionary comprehension to raise the values of a dictionary to the second power:

dict1 = {'a': 1, 'b': 2, 'c': 3, 'd': 4}
squared_dict = {key: num * num for (key, num) in dict1.items()}


{'a': 1, 'b': 4, 'c': 9, 'd': 16}

10. Simplify If Statements

Instead of this horrible mess:

if n == 0 or n == 1 or n == 2 or n == 3 or n == 4 or n == 5:

You can simply do this:

if n in [0, 1, 2, 3, 4, 5]


Thanks for reading. I hope you find them useful. Happy coding!

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