How do I use list comprehensions with nested lists in Python?

How do I use list comprehensions with nested lists in Python?

You can use list comprehensions to flatten a nested list or to create a new list based on conditions. For example, if you have a nested list like nested_list = [[1, 2], [3, 4], [5, 6]], you can flatten it using: flattened = [item for sublist in nested_list for item in sublist].

Can you explain how that works step by step?

Sure! The comprehension iterates over each sublist in nested_list, and then over each item in that sublist. It collects all items into a new list.

What if I want to filter the items, like only getting even numbers?

You can add a condition to the comprehension. For example: evens = [item for sublist in nested_list for item in sublist if item % 2 == 0] will give you only the even numbers.

That's really helpful! Can you give me another example?

Of course! If you have a nested list of strings and want to get their lengths, you could use: lengths = [len(item) for sublist in nested_list for item in sublist].