Getting started

This post will contain many interesting tips and tricks that I have learned these last months and I use constantly. So let’s get started 😄.

One-Liners

If you are familiar with python, you will know that the language has many powerful One-Liners expressions. For that reason, I will show you some of them.

List Comprehensions

The first one is probably my favorite, because it allows you to manipulate lists in a really cool way.
For example, instead of doing it that way, which is how almost everyone does it:

lis = []
for i in range(10):
    list.append(i)

You can do something more elegant like this one:

lis = [i for i in range(10)]

Moreover, you can use the if/else statement to, for example, create a list with only even numbers:

lis = [i for i in range(10) if i % 2 == 0]

Use of join with list comprehension

Related to list comprehensions, you can use the function join to join all elements on a list into a string. Continuing the previous example:

numbers_to_str = ",".join([str(i) for i in list if i % 2 == 0])
#Result: 0,2,4,6,8

Swapping of two numbers

If, for example, we are implementing the bubble sorting algorithm we usually do this:

 
def bubbleSort(lis):
    n = len(lis)
    aux = 0
    for i in range(n-1):
        for j in range(0, n-i-1):
            if lis[j] > lis[j + 1] :
                aux = lis[j]
                lis[j] = lis[j+1]
                lis[j+1] = aux

Nevertheless, with python, we can use the next one liner to swap the elements without the need to use the variable aux.

def bubbleSort(lis):
    n = len(lis)
    for i in range(n-1):
        for j in range(0, n-i-1):
            if lis[j] > lis[j + 1] :
                lis[j], lis[j + 1] = lis[j + 1], lis[j]

Reversing a list

With this technique you can create a reverse list in an exquisite way:

lis = [1, 2, 3]
reversed_list = lis[::-1]
  
print(reversed_list)
# Result: 3 2 1

Assign multiple variables in One Line

You can assign multiple values to multiple variables by separating variables and values with commas:

x, y, z = 3, 4, 5
print(x, y , z) 
#Result 3 4 5

If conditions

The final One-Liner that I want to share is a way to make conditions more readable. Normally programmers tend to do this:

if x == 2 and x == 3 and x == 5:
    print("Hello world!")

But if we use the operator in we can code it as:

if x in [2,3,5]:
    print("Hello world!")

Enumerate

When you want to go through a list and use both the index and the value contained in said memory position, this tip comes in handy.

Enumerate is a built-in function of Python and allows us to loop over an iterable and have an automatic counter. It essentially pairs every element in our list with the corresponding index. Most of the newcomers and even some advanced programmers are unaware of it.

lis = [2,4,1,5]
for i,value in enumerate(lis):
    print(i,value)
"""
Result
0 2
1 4
2 1 
3 5 
"""

Anti-Patterns

Anti-patterns are certain patterns in software development that are considered bad programming practices. Hopefully, with these examples, you will write better code for your development career.

Check if an element is inside a list

Consider using set or bisect for check if an element is in a large list:

# bad practice
list_of_letters = ["A", "B", "C", "A", "D", "B"]
check = "A" in list_of_letters

# good practice
set_of_letters = {"A", "B", "C", "D"}
check = "A" in set_of_letters

time_speed_image

Not using get to return default values from a dictionary

When you use get, python checks if the key exists. The second argument would be returned if this key doesn’t exist.

# bad practice
fruit_price = {
    "Apple" : 1
    "Orange": 2
    "Pear" : 3
}
get_price_of = "Apple"
if get_price_of in fruit_price:
    price =  fruit_price[get_price_of]
else:
    price = None 
# good practice
price = fruit_price.get(get_price_of,None)

Try/except blocks that don’t handle exceptions meaningfully

Ignoring the exception should never be done.

numbers = [0,1,2,3]

result = 0
for number in numbers:
    try:
        result += 1/num
    except:
        pass


#good practice
result = 0
for number in numbers:
    try:
        result += 1/num
    except ZeroDivisionError:
        print("Don't divide by zero!" )

# alternative you can use suppress 
from contextlib import suppress 
with suppress(Exception):
    for number in numbers:
        result += 1/num

Thanks for reading

If you think that the article has been useful to you, please share it and see you soon 😄 💥.

References

https://www.geeksforgeeks.org/powerful-one-liner-python-codes/ https://towardsdatascience.com/12-python-tips-and-tricks-for-writing-better-code-b57e7eea580b https://towardsdatascience.com/quick-python-tip-suppress-known-exception-without-try-except-a93ec34d3704