How to count number of items in a list python
IntroductionGetting the number of elements in a list in Python is a common operation. For example, you will need to know how many elements the list has whenever you iterate through it. Remember that lists can have a combination of integers, floats, strings, booleans, other lists, etc. as their elements: Show
If we count the elements in There are different ways to get the number of elements in a list. The approaches vary whether you want to count nested lists as one element or all the elements in the nested lists, or whether you're only interested in unique elements, and similar. Built-in Function len()The most straightforward way to get the number of elements in a list is to use the Python built-in function Let's look at the following example:
Which prints out:
As the name function suggests, Using a for LoopAnother way we can do this is to create a function that loops through the list using a The loop ends when it iterates over all the elements, therefore the count will represent the total number of elements in the list:
Running this code will print:
This is a much more verbose solution compared to the Get Number of Unique Elements in a ListLists can have multiple elements, including duplicates. If we want to get the number of elements without duplicates (unique elements) we can use another built-in function We then pass that into the
Which prints:
We can see that List of Lists using len()In the introduction, we saw that elements of lists can be of different data types. However, lists can have, in turn, lists as their elements. For example:
If we use the built-in function Check out our hands-on, practical guide to learning Git, with best-practices, industry-accepted standards, and included cheat sheet. Stop Googling Git commands and actually learn it!
Which prints:
Note that the empty list counts as one element. If a list within a list contains more than one element, they aren't taken into consideration. This is where a Get Number of Elements in a List Containing Other ListsIf we want to count all the elements inside a list
containing other lists, we can use a We will use the built-in function
The output is:
There are a few important things to note in this example. Firstly, this time the empty list did not affect the total count. This is because in every loop we consider the length of the current
nested list, and since the length of an empty list is 0, However, you can see that every character of the string Another fun way of doing the same thing as in the previous example is by using list comprehension:
This line essentially does two things. First, it creates a new list containing the lengths of all the elements of the original list. In our case that would be Nested ListsNested lists are lists that are elements of other lists. There can be multiple levels of lists inside one another:
We can see that Again, we initialize the Note that this is also the solution to the problems caused by the previous approach. Let's take a look at the code for counting elements in nested lists:
Running this code would give us:
Note that we used the built-in function The first
element ConclusionWe saw that according to the type of list we have, there are different ways to get the number of elements. With lists of lists and nested lists,
How do you count items in a list in Python?The most straightforward way to get the number of elements in a list is to use the Python built-in function len() . As the name function suggests, len() returns the length of the list, regardless of the types of elements in it.
What is count () in Python?Count() is a Python built-in function that returns the number of times an object appears in a list. The count() method is one of Python's built-in functions. It returns the number of times a given value occurs in a string or a list, as the name implies.
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