50 python one-liners everyone should know

I was always amazed by how easily things can be done using python. Some of the tedious tasks can be done in a single line of code using python. I have gathered some of my favorite one-liners from python. I have listed out 50 of them below with an example for each.

1. Anagram

`from collections import Counters1 = 'below's2 = 'elbow'print('anagram') if Counter(s1) == Counter(s2) else print('not an anagram')`

or we can also do this using the sorted() method like this.

`print('anagram') if sorted(s1) == sorted(s2) else print('not an anagram')`

2. Binary to decimal

`decimal = int('1010', 2)print(decimal) #10`

3. Converting string to lower case

`"Hi my name is Allwin".lower()# 'hi my name is allwin'"Hi my name is Allwin".casefold()# 'hi my name is allwin'`

4. Converting string to upper case

`"hi my name is Allwin".upper()# 'HI MY NAME IS ALLWIN'`

5. Converting string to byte

`"convert string to bytes using encode method".encode()# b'convert string to bytes using encode method'`

6. Copy files

`import shutil; shutil.copyfile('source.txt', 'dest.txt')`

7. Quicksort

`qsort = lambda l : l if len(l)<=1 else qsort([x for x in l[1:] if x < l[0]]) + [l[0]] + qsort([x for x in l[1:] if x >= l[0]])`

8. Sum of n consecutive numbers

`sum(range(0, n+1))`

This is not efficient and we can do the same using the below formula.

`sum_n = n*(n+1)//2`

9. Swap two values

`a,b = b,a`

10. Fibonacci series

`lambda x: x if x<=1 else fib(x-1) + fib(x-2)]`

11. Combine nested lists to a single list

`[item for sublist in main_list for item in sublist]`

12. Run an HTTP server

`python3 -m http.server 8000`

13. Reverse a list

`numbers[::-1]`

14. Factorial of a number

`import math; fact_5 = math.factorial(5)`

15. List comprehension using “for” and “if”

`even_list = [number for number in [1, 2, 3, 4] if number % 2 == 0]# [2, 4]`

16. Longest string from a list

`# words = ['This', 'is', 'a', 'list', 'of', 'words']max(words, key=len)# 'words'`

17. List comprehension

`li = [num for num in range(0,100)]# this will create a list of numbers from 0 to 99`

18. Set comprehension

`num_set = { num for num in range(0,100)}# this will create a set of numbers from 0 to 99`

19. Dictionary comprehension

`dict_numbers = {x:x*x for x in range(1,5) }# {1: 1, 2: 4, 3: 9, 4: 16}`

20. if-else

`print("even") if 4%2==0 else print("odd")`

21. Infinite while loop

`while 1:0`

22. Check the data type

`isinstance(2, int)isinstance("allwin", str)isinstance([3,4,1997], list)`

23. While loop

`a=5while a > 0: a = a - 1; print(a)`

24. Write to a file using the print statement

`print("Hello, World!", file=open('file.txt', 'w'))`

25. Count the frequency of a character in a string

`print("umbrella".count('l'))# 2`

26. Merge two lists

`list1.extend(list2)# contents of list 2 will be added to the list1`

27. Merge two dictionaries

`dict1.update(dict2)# contents of dictionary 2 will be added to the dictionary 1`

28. Merge two sets

`set1.update(set2)# contents of set2 will be copied to the set1`

29. Timestamp

`import time; print(time.time())`

30. Most frequent element

`numbers = [9, 4, 5, 4, 4, 5, 9, 5, 4]most_frequent_element = max(set(test_list), key=test_list.count)# 4`

However, this is not efficient and we can do the same using the collections module in a more efficient way like this.

`numbers = [9, 4, 5, 4, 4, 5, 9, 5, 4]from collections import Counterprint(Counter(numbers).most_common()[0][0])# 4`

31. Nested list comprehension

`numbers = [[num] for num in range(10)]# [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9]]`

32. Octal to decimal

`print(int('30', 8)) # 24`

33. Convert key-value pair to dictionary

`dict(name='allwin', age=23)`

34. Get quotient and remainder

`quotient, remainder = divmod(4,5)`

35. Remove duplicate elements from a list

`list(set([4, 4, 5, 5, 6]))`

36. Sort list in ascending order

First, let us sort the list using the sorted() method. The sorted method will return the sorted list.

`sorted([5, 2, 9, 1])# [1, 2, 5, 9]`

Next, let us sort this using the sort() method. The sort() method will sort the original list and not return anything.

`li = [5, 2, 9, 1]li.sort()print(li)# 1, 2, 5, 9`

37. Sort list in descending order

`sorted([5, 2, 9, 1], reverse=True)# [9, 5, 2, 1]`

38. Get a string of lower-case alphabets

`import string; print(string.ascii_lowercase)# abcdefghijklmnopqrstuvwxyz`

39. Get a string of upper case alphabets

`import string; print(string.ascii_uppercase)# ABCDEFGHIJKLMNOPQRSTUVWXYZ`

40. Get a string of digits from 0 to 9

`import string; print(string.digits)# 0123456789`

`print(int('da9', 16))# 3497`

`import time; print(time.ctime())# Thu Aug 13 20:16:23 2020`

43. Convert a list of strings to integers

`list(map(int, ['1', '2', '3']))# [1, 2, 3]`

44. Sort dictionary with keys

`# {'one': 1, 'four': 4, 'eight': 8}{key:d[key] for key in sorted(d.keys())}# {'eight': 8, 'four': 4, 'one': 1}`

45. Sort dictionary with values

`# x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}{k: v for k, v in sorted(x.items(), key=lambda item: item[1])}# {0: 0, 2: 1, 1: 2, 4: 3, 3: 4}`

46. Rotate a list

`# li = [1,2,3,4,5]# right to leftli[n:] + li[:n] # n is the no of rotationsli[2:] + li[:2][3, 4, 5, 1, 2]# left to rightli[-n:] + li[:-n]li[-1:] + li[:-1] [5, 1, 2, 3, 4]`

47. Remove numbers from a string

`''.join(list(filter(lambda x: x.isalpha(), 'abc123def4fg56vcg2')))# abcdeffgvcg`

48. Transpose matrix

`list(list(x) for x in zip(*old_list))# old_list = [[1, 2, 3], [3, 4, 6], [5, 6, 7]]# [[1, 3, 5], [2, 4, 6], [3, 6, 7]]`

49. Filter even numbers from a list

`list(filter(lambda x: x%2 == 0, [1, 2, 3, 4, 5, 6] ))# [2, 4, 6]`

50. Unpacking values

`a, *b, c = [1, 2, 3, 4, 5]print(a) # 1print(b) # [2, 3, 4]print(c) # 5`

Conclusion

I have provided the link to my Github repo below which has all these one-liners. Feel free to contribute more amazing one-liners. Happy coding!

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Python Developer | Django Developer | Python Enthusiast

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Allwin Raju

Python Developer | Django Developer | Python Enthusiast