30 Essential Python Tricks Every Developer Should Know

1. Python version

Since January 1 2020 the official Python project no longer supports Python 2; all examples in this article require Python 3.

2. Check minimum Python version

You can guard your script against old versions:

if not sys.version_info > (2, 7):
    # berate your user for running a 10‑year old python version
elif not sys.version_info >= (3, 5):
    # kindly tell your user they need to upgrade because you're using 3.5 features

3. IPython

IPython is an enhanced interactive shell with auto‑completion and many useful magic commands:

%cd – change the current working directory

%edit – open an editor and execute the edited code on close

%env – show current environment variables

%pip install [pkgs] – install packages without leaving the shell

%time and %timeit – measure execution time of Python code

You can also retrieve the output of a previous command via Out[3] and install IPython with:

pip3 install ipython

4. List comprehensions

Use list comprehensions to build lists concisely: [expression for item in list if conditional] Examples:

mylist = [i for i in range(10)]
print(mylist)  # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

squares = [x**2 for x in range(10)]
print(squares)  # [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

def some_function(a):
    return (a + 5) / 2
my_formula = [some_function(i) for i in range(10)]
print(my_formula)  # [2, 3, 3, 4, 4, 5, 5, 6, 6, 7]

filtered = [i for i in range(20) if i % 2 == 0]
print(filtered)  # [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]

5. Inspect object memory usage

Use sys.getsizeof to see how much memory a container occupies:

import sys
mylist = range(0, 10000)
print(sys.getsizeof(mylist))  # 48
myreallist = [x for x in range(0, 10000)]
print(sys.getsizeof(myreallist))  # 87632

6. Return multiple values

Functions can return several values directly:

def get_user(id):
    # fetch user from database
    return name, birthdate

name, birthdate = get_user(4)

If more than three values are needed, consider returning a data class.

7. Data classes (Python 3.7+)

Data classes reduce boilerplate, provide __eq__, __repr__, and type hints:

from dataclasses import dataclass

@dataclass
class Card:
    rank: str
    suit: str

card = Card("Q", "hearts")
print(card == card)          # True
print(card.rank)             # Q
print(card)                  # Card(rank='Q', suit='hearts')

8. Swap variables

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

9. Merge dictionaries (Python 3.5+)

dict1 = {'a': 1, 'b': 2}
dict2 = {'b': 3, 'c': 4}
merged = {**dict1, **dict2}
print(merged)  # {'a': 1, 'b': 3, 'c': 4}

10. Capitalize strings

mystring = "10 awesome python tricks"
print(mystring.title())  # 10 Awesome Python Tricks

11. Split string into list

mystring = "The quick brown fox"
mylist = mystring.split(' ')
print(mylist)  # ['The', 'quick', 'brown', 'fox']

12. Join list into string

mylist = ['The', 'quick', 'brown', 'fox']
mystring = " ".join(mylist)
print(mystring)  # The quick brown fox

13. Emoji handling

pip3 install emoji
import emoji
result = emoji.emojize('Python is :thumbs_up:')
print(result)  # Python is 👍
result = emoji.demojize('Python is 👍')
print(result)  # Python is :thumbs_up:

14. List slicing

a[start:stop:step]

Defaults: start = 0, stop = end, step = 1.

first_two = [1, 2, 3, 4, 5][0:2]
print(first_two)  # [1, 2]
steps = [1, 2, 3, 4, 5][0:5:2]
print(steps)      # [1, 3, 5]
mystring = "abcdef"[::2]
print(mystring)  # ace

15. Reverse string/list

revstring = "abcdefg"[::-1]
print(revstring)  # gfedcba
revarray = [1, 2, 3, 4, 5][::-1]
print(revarray)   # [5, 4, 3, 2, 1]

16. Display images (Pillow)

pip3 install Pillow
from PIL import Image
im = Image.open("kittens.jpg")
im.show()
print(im.format, im.size, im.mode)  # JPEG (1920, 1357) RGB

17. map function

def upper(s):
    return s.upper()
mylist = list(map(upper, ['sentence', 'fragment']))
print(mylist)  # ['SENTENCE', 'FRAGMENT']
list_of_ints = list(map(int, "1234567"))
print(list_of_ints)  # [1, 2, 3, 4, 5, 6, 7]

18. Unique elements with set

mylist = [1,1,2,3,4,5,5,5,6,6]
print(set(mylist))  # {1, 2, 3, 4, 5, 6}
print(set("aaabbbcccdddeeefff"))  # {'a', 'b', 'c', 'd', 'e', 'f'}

19. Most frequent value

test = [1,2,3,4,2,2,3,1,4,4,4]
print(max(set(test), key=test.count))  # 4

20. Progress bar

pip3 install progress
from progress.bar import Bar
bar = Bar('Processing', max=20)
for i in range(20):
    # do some work
    bar.next()
bar.finish()

21. Underscore in IPython

In[1]: 3 * 3
Out[1]: 9
In[2]: _ + 3
Out[2]: 12

22. Quick web server

python3 -m http.server

23. Multi‑line strings

s1 = """Multi line strings can be put
between triple quotes. It's not ideal
when formatting your code though"""
print(s1)

s2 = ("You can also concatenate multiple
" +
      "strings this way, but you'll have to
" +
      "explicitly put in the newlines")
print(s2)

24. Ternary operator

x = "Success!" if (y == 2) else "Failed!"

25. Count elements with Counter

from collections import Counter
mylist = [1,1,2,3,4,5,5,5,6,6]
c = Counter(mylist)
print(c)  # Counter({5: 3, 1: 2, 6: 2, 2: 1, 3: 1, 4: 1})
print(Counter("aaaaabbbbbccccc"))  # Counter({'a':5,'b':5,'c':5})

26. Chained comparisons

x = 10
if 5 < x < 15:
    print("Yes")

27. Terminal colors (colorama)

from colorama import Fore, Back, Style
print(Fore.RED + 'some red text')
print(Back.GREEN + 'and with a green background')
print(Style.DIM + 'and in dim text')
print(Style.RESET_ALL)
print('back to normal now')

28. Date handling (python‑dateutil)

pip3 install python-dateutil
from dateutil.parser import parse
logline = 'INFO 2020-01-01T00:00:01 Happy new year, human.'
timestamp = parse(logline, fuzzy=True)
print(timestamp)  # 2020-01-01 00:00:01

29. Integer division

Python 2 uses / for integer division; Python 3 uses // for floor division and / for true division.

# Python 2
5 / 2   # 2
5 / 2.0 # 2.5
# Python 3
5 / 2   # 2.5
5 // 2  # 2

30. Detect charset with chardet

pip install chardet
chardetect somefile.txt
# output: somefile.txt: ascii with confidence 1.0