Here are a couple of examples that demonstrate both the default behavior and the behavior when given an index: > my_list = The pop() method removes and returns the last item by default unless you give it an index argument. Extend appended all values from l2 to l1. While l1 got extended with the elements of l2, l2 stayed the same. The alternative is to extend one list with another, using the extend method: > l1 = Here’s how you can add two lists together. Add all elements of one list to the other with the extend method.‘Add’ them together with the + operator.Combine or merge two listsĪnother way of adding elements is adding all the elements from one list to the other. When calling append on a list, we append an object to the end of the list: > my_list = List objects have a number of useful built-in methods, one of which is the append method. I’ll describe and demonstrate them all in this section. What you use, depends on the situation you’re in. There are several ways to remove data from a list. Let’s see how we can add and remove data. So to request an element in that list, you need to again use a couple of brackets: > my_list =, , ] When you access an element that is a list, that list is returned. > my_list # get the 2nd last elementĪccessing nested list elements is not that much different. E.g., to get the last element of a list, you can do this: > my_list = In this case, we start counting at -1 instead of 0. If you want to get elements from the end of the list, you can supply a negative value. In my article on exceptions and the try and except statements, I’ve written about this subject more in-depth in the section on best practices. In this case, Python throws an Inde圎rror exception, with the explanation ‘list index out of range’. Here are a few examples: > my_list = Īs you can see, you can’t access elements that don’t exist. Since computers start counting at 0, the first element is in position 0, the second element is in position 1, etcetera. To access an individual list element, you need to know the position of that element. E.g., you can materialize the range function into a list of actual values, or convert a Python set or tuple into a list: > list(range(1, 4)) So you can convert anything that is iterable into a list. This function takes one argument: an object that is iterable. If you want to convert another Python object to a list, you can use the list() function, which is actually the constructor of the list class itself. The class of a list is called ‘list’, with a lower case L. Python lists, like all Python data types, are objects. Game_board =, , ] Using the list() function The following lists are all valid: my_list = The elements in a list can have any data type, and they can be mixed. Lists contain regular Python objects, separated by commas and surrounded by brackets. Let’s start by creating a list: my_list =
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |