How to Find Python List Length?

In this article, we’ll learn how to find the length of a list in Python programming.

Python lists are ordered, changeable collections of data that can contain duplicate entries.

To find the Python list length, you can use the Python len() method.

What is List in Python?

A list in Python stores a sequence of data.

There are six data types in python that can store sequences, but the most common and reliable is a list.

To learn more about Python List, you can check out the List in Python with Examples.

A list is a type of mutable data. Once a list is created, its elements, values, and order can be changed.

The list items are separated by a comma (,) and surrounded by square brackets [].

Example:

list1 = ['Prince', 'Grace', 1999, 1998];
list2 = [1, 2, 3, 4, 5 ];
list3 = ["A1", "B2", "C3", "D4"]

How to Find the Length of a List in Python?

To find list length in Python, there are two basic function to find the length of a list in Python:

Len() Method

To get the length of list in Python, there is a built-in function called len() which returns the number of items in a list, tuple, array, dictionary, etc.

The len() method is a quick and easy way to return the length of a list in Python. This is the method that programmers use most often these days.

Syntax:

len(list)

The List parameter is a list. It returns the number of elements in the list.

Example:

List1 = ["a", "b", "c", "d", "e", "f"]
print ("Length of the List1 = ", len(List1))

Output:

Length of the List1 = 6

Naive Method

To get the size of list in python, the most common way to find the length of a list in Python is to use the len() method. However, there is another basic method that also provides the length of the list.

The Naive method loops through the list and counts the number of items until the last item is reached. This is the most basic thing you can do when you don’t have any other good ideas.

Example:

List1 = ["a", "b", "c", "d", "e", "f"]
print ("The list is : " + str(List1))
counter = 0
for i in List1:

    # Incrementing counter variable
    counter = counter + 1
print ("Length of List1 using naive method = " + str(counter))

Output:

The list is : ['a', 'b', 'c', 'd', 'e', 'f']
Length of List1 using naive method = 6

Length_hint() Method

Python’s operator module has the length_hint() function for calculating the total number of items list entries.

The operator.length_hint() method determines the length of an iterable such as a list, tuple, or dictionary.

Syntax:

length_hint(list)

Note: Before using the length_hint, import it from the operator module.

Example:

from operator import length_hint

List1 = ["a", "b", "c", "d", "e", "f"]
print("List1 values are:",List1)

# Using the length_hint operator
print ("Length of the List1 using the length_hint operator =", length_hint(List1))

Output:

List1 values are: ['a', 'b', 'c', 'd', 'e', 'f']
Length of the List1 using the length_hint operator = 6

What is Len() in Python?

One of Python’s built-in functions is called len(). Some objects can use the built-in len() function, but others can’t. The len() function only works with things that have a length.

The len() function in Python count the number of items in a list using len.

The function takes an object as its argument and gives back the object’s length. The len() documentation provides further information:

Return the length (the number of items) of an object. The argument may be a sequence (such as a string, bytes, tuple, list, or range) or a collection (such as a dictionary, set, or frozen set).

Python Documentation

What does Len () do in Python?

The length of an object is given by the len() function. It tells you how many items are in an inerrable or how many characters are in a string, list, tuple, dictionary, etc.

Conclusion

After reading this article, we should now have a good understanding of the three ways to get the list length.

And in case you’re wondering, what method should you use to get the length of the list?

I think you should use len() function in python list instead of python using for loop and length hint because you don’t have to do much to use it. 

Also, it seems that len() is quicker than both the for loop and length hint.

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