## DEV Community

Dharaneeswaran R

Posted on • Updated on

# Write Better Python Code

## Introduction

This article has the collection python coding practices that I have learned over last few months for writing more idiomatic python code.

## 1. Multiple Assignment

Initialise same value for different variables.

``````# Instead of this
x = 10
y = 10
z = 10

# Use this
x = y = z = 10
``````

## 2. Variable Unpacking

``````x, y = [1, 2]
# x = 1, y = 2

x, *y = [1, 2, 3, 4, 5]
# x = 1, y = [2, 3, 4, 5]

x, *y, z = [1, 2, 3, 4, 5]
# x = 1, y = [2, 3, 4], z = 5
``````

## 3. Swapping Variables

``````# Instead of this
temp = x
x = y
y = temp

# Use this
x, y = y, x
``````

## 4. Name Casing

In python `snake_case` is preferred over `camelCase` for variables and functions names.

``````# Instead of this
def isEven(num):
pass

# Use this
def is_even(num):
pass
``````

## 5. Conditional Expressions

You can combine if-else statements into one line.

``````# Instead of this
def is_even(num):
if num % 2 == 0:
print("Even")
else:
print("Odd")

# Use this
def is_even(num):
print("Even") if num % 2 == 0 else print("Odd")

# Or this
def is_even(num):
print("Even" if num % 2 == 0 else "Odd")
``````

## 6. String Formatting

``````name = "Dobby"
item = "Socks"

print("%s likes %s." %(name, item))

# Or this
print("{} likes {}.".format(name, item))

# Use this
print(f"{name} likes {item}.")
``````

f-strings are introduced in Python 3.6 and faster and more readable than other string formatting methods.

## 7. Comparison Operator

``````# Instead of this
if 99 < x and x < 1000:
print("x is a 3 digit number")

# Use this
if 99 < x < 1000:
print("x is a 3 digit number")
``````

## 8. Iterating over a list or tuple

We don't need to use indices to access list elements. Instead we can do this.

``````numbers = [1, 2, 3, 4, 5, 6]

for i in range(len(numbers)):
print(numbers[i])

# Use this
for number in numbers:
print(number)

# Both of these yields the same output
``````

## 9. Using enumerate()

When you need both indices and values, we can use `enumerate()`.

``````names = ['Harry', 'Ron', 'Hermione', 'Ginny', 'Neville']

for index, value in enumerate(names):
print(index, value)
``````

## 10. Using Set for searching

Searching in a set is faster(O(1)) compared to list(O(n)).

``````# Instead of this
l = ['a', 'e', 'i', 'o', 'u']

def is_vowel(char):
if char in l:
print("Vowel")

# Use this
s = {'a', 'e', 'i', 'o', 'u'}

def is_vowel(char):
if char in s:
print("Vowel")
``````

## 11. List comprehension

Consider the following program to multiply the elements of the list into 2 if they are even.

``````arr = [1, 2, 3, 4, 5, 6]
res = []

for num in arr:
if num % 2 == 0:
res.append(num * 2)
else:
res.append(num)

# Use this
res = [(num * 2 if num % 2 == 0 else num) for num in arr]
``````

## 12. Iterating Dictionary

Using `dict.items()` to iterate through a dictionary.

``````roll_name = {
315: "Dharan",
705: "Priya",
403: "Aghil"
}