Python | Count occurrences of an element in a list
Last Updated :
24 Nov, 2023
Given a list in Python and a number x, count the number of occurrences of x in the given list.
Examples:
Input: lst = [15, 6, 7, 10, 12, 20, 10, 28, 10], x = 10
Output: 3
Explanation: 10 appears three times in given list.
Input: lst = [8, 6, 8, 10, 8, 20, 10, 8, 8], x = 16
Output: 0
Explanation: 16 appears zero times in given list.
Count Occurrences of Item in Python List
Below are the methods by which we can count all occurrences of an element in a Python List.
Python Count occurrences using a Loop in Python
We keep a counter that keeps on increasing if the required element is found in the list.
Python3
def countX(lst, x):
count = 0
for ele in lst:
if (ele == x):
count = count + 1
return count
lst = [8, 6, 8, 10, 8, 20, 10, 8, 8]
x = 8
print('{} has occurred {} times'.format(x,
countX(lst, x)))
|
Output
8 has occurred 5 times
Python Count Occurences using List Comprehension
In this example, we are using list comprehension to count all occurrences of an element in a Python list.
Python3
l = [1, 1, 2, 2, 2, 3, 3, 4, 4, 5, 5]
ele=1
x=[i for i in l if i==ele]
print("the element",ele,"occurs",len(x),"times")
|
Output
the element 1 occurs 2 times
Python Count using Enumerate Function
In this example, we are using enumerate function to count all occurrences of an element in a Python list.
Python3
l = [1, 1, 2, 2, 2, 3, 3, 4, 4, 5, 5]
ele=1
x=[i for j,i in enumerate(l) if i==ele]
print("the element",ele,"occurs",len(x),"times")
|
Output
the element 1 occurs 2 times
Count occurrences of an element using count()
The idea is to use the list method count() to count the number of occurrences.
Python3
def countX(lst, x):
return lst.count(x)
lst = [8, 6, 8, 10, 8, 20, 10, 8, 8]
x = 8
print('{} has occurred {} times'.format(x,
countX(lst, x)))
|
Output
8 has occurred 5 times
Python Count occurrences of an element in a list using Counter()
The counter method returns a dictionary with occurrences of all elements as a key-value pair, where the key is the element and the value is the number of times that element has occurred.
Python3
from collections import Counter
l = [1, 1, 2, 2, 3, 3, 4, 4, 5, 5]
x = 3
d = Counter(l)
print('{} has occurred {} times'.format(x, d[x]))
|
Output
3 has occurred 2 times
Count occurrences of an element using countOf()
Operator.countOf() is used for counting the number of occurrences of b in a. It counts the number of occurrences of value. It returns the Count of a number of occurrences of value.
Python3
import operator as op
l = [1, 1, 2, 2, 2, 3, 3, 4, 4, 5, 5]
x = 2
print(f"{x} has occurred {op.countOf(l, x)} times")
|
Output
2 has occurred 3 times
Using Python Dictionary Comprehension
Python allows dictionary comprehensions. We can create dictionaries using simple expressions. A dictionary comprehension takes the form {key: value for (key, value) in iterable}
Python3
lis = ['a', 'd', 'd', 'c', 'a', 'b', 'b', 'a', 'c', 'd', 'e']
occurrence = {item: lis.count(item) for item in lis}
print(occurrence.get('e'))
|
Using the Pandas library
Pandas Series.value_counts() function return a Series containing counts of unique values. The resulting object will be in descending order so that the first element is the most frequently-occurring element.
Python3
import pandas as pd
l = [1, 1, 2, 2, 2, 3, 3, 4, 4, 5, 5]
count = pd.Series(l).value_counts()
print("Element Count")
print(count)
|
Output:
Element Count
2 3
1 2
3 2
4 2
5 2
dtype: int64
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