Nested Loops in Python This document explains how to use nested loops in Python. Nested loops are loops inside other loops, and they are useful for working with multi-dimensional data, such as ...

Basically what happens with a nested loop is the inner loop runs in its entirety every iteration of the ourter loop. Let's take a look at an example before diving too much deeper.

The for loop construction in Python easily iterates over a collection of items. Here’s what you need to know to use it well.

That loop is creating a load of empty dictionaries, then your second loop is overwriting those dictionaries with new ones that have your desired data already contained within.