Lists can also be spread out over multiple lines. This means that the following statements are equivalent: > l2 = Trailing commas and whitespace around the individual elements don't make a difference in how things are interpreted. We can also refer to other variables from within lists. So the l1 is an instance of the class called list. Creating listsįirst, some basic syntax for creating lists. Open up a Python3 shell if you want to follow along. In this section, we'll run through a bunch of examples. If Rob decides to wear a blue t-shirt, then that means that Robert and Bob are wearing a blue t-shirt - it's the same t-shirt. This also means that if you do something that changes Rob, it would affect Robert and Bob. In Python this is like: > id(bob) = id(robert) Rob's social security number is the same as Bob's. Bob's social security number is the same as Robert's social security number. His mother calls him Robert, his siblings call him Rob, and his friends call him Bob. That is, they are in the same place in memory.Īs an analogy, let's say we have a human named Robert. If we have two values that have the same id output, then they are the same object. So in plain English, the id function returns something that represents the unique identity of an object. (CPython uses the object's memory address.) This is guaranteed to be unique among simultaneously existing objects. We'll be making use of Python's built in id function quite a bit in the examples that follow, so we'll start off by making sure we understood it. If you are running this stuff in Python2, some things might turn out a little differently. The examples below are all written in Python3. We'll finish off by comparing lists to some other iterable types. After that, we'll look at some examples of leveraging loops, comprehensions, and recursion for creating lists. We'll start off by looking at lists in isolation: how we make them and how to interact with them. This article aims to remove some of the confusion around these questions and more. What's a list? How does it compare to a tuple and set? How about dictionaries? What's mutability all about? What are iterators and are they worth caring about? There seems to be quite a lot of confusion surrounding Python lists and certain data structures comparable to lists.
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