In Python, lists are one of the most commonly used data structures to store an ordered collection of items.
In this article, we'll learn how to find the number of elements in a given list with different methods.
Example
Input: [1, 2, 3.5, geeks, for, geeks, -11]
Output: 7
Let's explore various ways to doing it:
Using len() function
The simplest and most efficient way is to use Python’s built-in len() function.
a = [1, 2, 3, 4]
print(len(a))
Output
4
Explanation: len(a) returns the total number of items in the list a.
Using operator.length_hint()
The length_hint() function from the operator module gives an estimated length of a collection.
from operator import length_hint
a = [1, 2, 3, 4]
print(length_hint(a))
Output
4
Explanation:
- The code imports the length_hint function from the operator module.
- length_hint(a) returns the number of elements present in the list a which is 4. .
Using for loop
We can declare a counter variable to count the number of elements in the list while iterating the list using a for loop.
a = [1, 2, 3, 4]
count = 0
for _ in a:
count += 1
print(count)
Output
4
Explanation: We initialize count as 0 and increment it for every element in the list.
Using Numpy Library
We can also use the popular NumPy library's size() function.
import numpy as np
a = [1, 2, 3, 4]
print(np.size(a))
Output
4
Explanation: np.size(a) returns the total number of elements in the array or list.
