Here, a new list letters is defined, with four elements. ![]() index(), that you can append to the object in question to locate the index of a given element: > letters = This is the sequential numeric position of the element in the iterable, where the first item is at location 0, the second is at 1, and so on. Most iterable objects allow you to locate the index of the desired element. There's another property of iterable objects that you can exploit to find the length of a Python list. This should be the total number of items in the list, and since we know the true length of my_list we can verify that this is indeed the case: > count When the iterator reaches the end of the list, the counter will stop and return the last number it was incremented to. The loop states that for each element i in the list, the counter should be incremented by one. Here, you initialize a variable count to zero, then you start a for loop. ![]() A for loop is a good candidate for finding Python list length using counters: > count = 0 To use a counter, you start with some arbitrary number, usually 0, and increment this number each time a loop is performed. Let's continue on with my_list, since we know the true answer and can verify our implementation. You can use the same concept to figure out the length of a list. In each of these scenarios, you'll likely be using a counter to keep track of how many iterations have completed. For instance, you may be processing all the rows in a CSV file, updating all the tables in a database, or looping over a code block until an error state is triggered. This might be the case whenever you're using iteration. However, in several cases you'll want to know the length of a list that doesn't exist yet. ![]() In the previous example, you defined a list and then used the Python function len() to return the number of elements in it. You then pass in your list to len(), which correctly returns 5 as the number of objects the list currently holds. Here, you define a list my_list with the integers 1 through 5 as elements. To find a Python list's length, you would then use len() as follows: > my_list = ![]() The function then returns the number of items in the given object. The argument x can be any of several different types of iterable objects, such as collections (sets and dictionaries) or sequences (such as strings, tuples, or - relevant to this article - lists). The len() function (which is short for length) has the following syntax: len(x) Python List Length With len()Īs with most basic operations, there's a built-in function that comes with every installation of Python for list length. In this article, you'll take a quick look a few different ways to find the length of a list in Python. The key phrase here is "any number of." How would you determine, then, exactly what number of items a list holds? In other words, how can you find the length of a Python list? The one you're most likely to come across early on in your developer journey is the list, which can dynamically hold any number of elements, even elements of differing data types. Python has a number of different data structures that you can use to hold collections of information.
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