20 Essential Python Tips to Improve Code Readability and Efficiency

Python's readability and simplicity are two major reasons for its popularity; this article introduces 20 common Python techniques that improve code readability and can save a lot of development time.

1. String reversal

# Reversing a string using slicing

my_string = "ABCDE"
reversed_string = my_string[::-1]
print(reversed_string)
# Output
# EDCBA

2. Capitalize first letter of each word

my_string = "my name is chaitanya baweja"
# using the title() function of string class
new_string = my_string.title()
print(new_string)
# Output
# My Name Is Chaitanya Baweja

3. Find unique characters in a string

my_string = "aavvccccddddeee"
# converting the string to a set
temp_set = set(my_string)
# stitching set into a string using join
new_string = ''.join(temp_set)
print(new_string)
# Output
# cdvae

4. Repeat a string or list n times

n = 3  # number of repetitions
my_string = "abcd"
my_list = [1,2,3]
print(my_string * n)   # abcdabcdabcd
print(my_list * n)     # [1,2,3,1,2,3,1,2,3]

5. List comprehension for element-wise multiplication

# Multiplying each element in a list by 2
original_list = [1,2,3,4]
new_list = [2*x for x in original_list]
print(new_list)
# Output
# [2,4,6,8]

6. Variable swapping

a = 1
b = 2

a, b = b, a
print(a)  # 2
print(b)  # 1

7. Split a string into a list of substrings

string_1 = "My name is Chaitanya Baweja"
string_2 = "sample/ string 2"
# default separator ' '
print(string_1.split())
# ['My', 'name', 'is', 'Chaitanya', 'Baweja']
# defining separator as '/'
print(string_2.split('/'))
# ['sample', ' string 2']

8. Join multiple strings into one string

list_of_strings = ['My','name','is','Chaitanya','Baweja']
print(','.join(list_of_strings))
# Output
# My,name,is,Chaitanya,Baweja

9. Check if a string is a palindrome

my_string = "abcba"
if my_string == my_string[::-1]:
    print("palindrome")
else:
    print("not palindrome")
# Output
# palindrome

10. Count occurrences of each element in a list

from collections import Counter
my_list = ['a','a','b','b','b','c','d','d','d','d','d']
count = Counter(my_list)
print(count)
# Counter({'d': 5, 'b': 3, 'a': 2, 'c': 1})
print(count['b'])   # 3
print(count.most_common(1))  # [('d', 5)]

11. Determine if two strings are anagrams

from collections import Counter
str_1, str_2, str_3 = "acbde", "abced", "abcda"
cnt_1, cnt_2, cnt_3 = Counter(str_1), Counter(str_2), Counter(str_3)
if cnt_1 == cnt_2:
    print('1 and 2 anagram')
if cnt_1 == cnt_3:
    print('1 and 3 anagram')
# Output
# 1 and 2 anagram

12. Use try‑except‑else‑finally for error handling

a, b = 1, 0
try:
    print(a / b)
except ZeroDivisionError:
    print("division by zero")
else:
    print("no exceptions raised")
finally:
    print("Run this always")
# Output
# division by zero
# Run this always

13. Enumerate a list to get index/value pairs

my_list = ['a','b','c','d','e']
for index, value in enumerate(my_list):
    print('{0}: {1}'.format(index, value))
# 0: a
# 1: b
# 2: c
# 3: d
# 4: e

14. Check memory size of an object

import sys
num = 21
print(sys.getsizeof(num))
# In Python 3, 28

15. Merge dictionaries

dict_1 = {'apple': 9, 'banana': 6}
dict_2 = {'banana': 4, 'orange': 8}
combined_dict = {**dict_1, **dict_2}
print(combined_dict)
# Output
# {'apple': 9, 'banana': 4, 'orange': 8}

16. Measure execution time of a code block

import time
start_time = time.time()
# Code to check follows
for i in range(10**5):
    a, b = 1, 2
    c = a + b
# Code to check ends
end_time = time.time()
time_taken_in_micro = (end_time - start_time) * (10**6)
print(time_taken_in_micro)
# Example output
# 18770.217895507812

17. Flatten a nested list

from iteration_utilities import deepflatten

def flatten(l):
    return [item for sublist in l for item in sublist]

l = [[1,2,3],[3]]
print(flatten(l))
# [1, 2, 3, 3]

l = [[1,2,3],[4,[5]],[6,7]],[[8],[9,[10]]]]
print(list(deepflatten(l, depth=3)))
# [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

18. Randomly sample elements from a list

import random
my_list = ['a','b','c','d','e']
num_samples = 2
samples = random.sample(my_list, num_samples)
print(samples)
# e.g., ['a', 'e'] (any two random values)

19. Convert an integer into a list of its digits

num = 123456
# using map
list_of_digits = list(map(int, str(num)))
print(list_of_digits)
# [1, 2, 3, 4, 5, 6]
# using list comprehension
list_of_digits = [int(x) for x in str(num)]
print(list_of_digits)
# [1, 2, 3, 4, 5, 6]

20. Check uniqueness of list elements

def unique(l):
    if len(l) == len(set(l)):
        print("All elements are unique")
    else:
        print("List has duplicates")

unique([1,2,3,4])   # All elements are unique
unique([1,1,2,3])   # List has duplicates

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