Python Tips

Don’t create your own function if there is already a built-in Python function for that task. Built-in functions like sum, max, filter, map, etc are implemented in C so they are very efficient. Use them if you can.
Above is the comparison between the speed of using a built-in sum and the speed of using a custom sum. A little bit different in speed matters when you work with a large array.
Find a full list of Python built-in functions here.

If you want to call your class instance like a function, add __call__method to your class. Above is an example of how it works.

When working with a large number in Python, it can be difficult to figure out how many digits that number has. Python 3.6 and above allows you to use underscores as visual separators to group digits.
In the example above, I use underscores to group decimal numbers by thousands.
Link to the source code.

You can turn a list of iterables into 2 separate iterables using zip(*list).

When you create a copy of a Python list using the = operator, a change in the new list will lead to the change in the old list. It is because both lists point to the same object.
Instead of using = operator, use copy() method. Now your old list will not change when you change your new list. Find an example above.
Link to the source code.

When assigning the values returned from a function, you might want to ignore some values that are not used in future code. If so, assign those values to underscore _.
Above is an example.

If you want to repeat a loop a specific number of times but don’t care about the index, you can use _. Above is an example.

When a Python function returns many values, it can be confusing as to which value is returned first, second, or third, etc. A better idea is to return using a Python dictionary like below.
To access 'a', for example, you just need to call values['a']. You don’t need to be worried that you will access the wrong value because of the wrong order.
If you happen to change the order of the outputs in your function, you still access the right value.
 

Have you ever executed some lines of code that take a long time to run but the next line of code caused the error so you lost the output of the previous lines of code?
You can use pickle to save the immediate output. If there is an error, you can load that output and continue where you left off

If you are using a for loop and you want to know what the error is when it occurs without stopping the for loop, use try and except.
Remember to add Exception as e after except statement to print the error like above.