Python List count() method
Python List count() is an inbuilt function in Python that returns the count of how many times a given object occurs in a List. The count() function is used to count elements on a list as well as a string.
Syntax:
list_name.count(object)
Parameters:
The object is the things whose count is to be returned.
Returns:
count() method returns the count of how many times object occurs in the list.
Exception:
If more then 1 parameter is passed in count() method, it returns a TypeError.
Example 1: Use of count()
- Python3
# Python3 program to count the number of times# an object appears in a list using count() methodlist1 = [1, 1, 1, 2, 3, 2, 1]# Counts the number of times 1 appears in list1print(list1.count(1))list2 = ['a', 'a', 'a', 'b', 'b', 'a', 'c', 'b']# Counts the number of times 'b' appears in list2print(list2.count('b'))list3 = ['Cat', 'Bat', 'Sat', 'Cat', 'cat', 'Mat']# Counts the number of times 'Cat' appears in list3print(list3.count('Cat')) |
Output:
4 3 2
Example 2: TypeError
- Python3
# Python3 program to demonstrate# the error in count() methodlist1 = [1, 1, 1, 2, 3, 2, 1]# Error when two parameters is passed.print(list1.count(1, 2)) |
Output:
Traceback (most recent call last):
File "/home/41d2d7646b4b549b399b0dfe29e38c53.py", line 7, in
print(list1.count(1, 2))
TypeError: count() takes exactly one argument (2 given)
Example 3: Count Tuple and List Elements Inside List
- Python3
# Python3 program to count the number of times# an object appears in a list using count() methodlist1 = [ ('Cat', 'Bat'), ('Sat', 'Cat'), ('Cat', 'Bat'), ('Cat', 'Bat', 'Sat'), [1, 2], [1, 2, 3], [1, 2] ]# Counts the number of times 'Cat' appears in list1print(list1.count(('Cat', 'Bat')))# Count the number of times sublist# '[1, 2]' appears in list1print(list1.count([1, 2])) |
Output:
2 2
Practical Application
Let’s say we want to count each element in a list and store it in another list or say dictionary.
- Python3
# Python3 program to count the number of times# an object appears in a list using count() methodlst = ['Cat', 'Bat', 'Sat', 'Cat', 'Mat', 'Cat', 'Sat']# To get the number of occurrences# of each item in a listprint ([ [l, lst.count(l)] for l in set(lst)])# To get the number of occurrences# of each item in a dictionaryprint (dict( (l, lst.count(l) ) for l in set(lst))) |
Output:
[['Mat', 1], ['Cat', 3], ['Sat', 2], ['Bat', 1]]
{'Bat': 1, 'Cat': 3, 'Sat': 2, 'Mat': 1}
Last Updated on November 13, 2021 by admin