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Python list function | count()
  • Last Updated : 18 Sep, 2018

count() is an inbuilt function in Python that returns count of how many times a given object occurs in list.

Syntax :

list_name.count(object) 

Parameters :

Object is the things whose count is to be returned. 

Returns :

count() method returns count of how many times obj occurs in list.

Exception :



If more then 1 parameter is passed in count() method, 
it returns a TypeError.

 
Code #1




# Python3 program to count the number of times
# an object appears in a list using count() method 
  
list1 = [1, 1, 1, 2, 3, 2, 1
  
# Counts the number of times 1 appears in list1
print(list1.count(1)) 
  
list2 = ['a', 'a', 'a', 'b', 'b', 'a', 'c', 'b'
  
# Counts the number of times 'b' appears in list2
print(list2.count('b')) 
  
list3 = ['Cat', 'Bat', 'Sat', 'Cat', 'cat', 'Mat']
  
# Counts the number of times 'Cat' appears in list3
print(list3.count('Cat'))

Output :

4
3
2

 
Code #2 : TypeError




# Python3 program to demonstrate
# the error in count() method
  
list1 = [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)

 
Code #3




# Python3 program to count the number of times
# an object appears in a list using count() method 
  
list1 = [ ('Cat', 'Bat'), ('Sat', 'Cat'), ('Cat', 'Bat'),
          ('Cat', 'Bat', 'Sat'), [1, 2], [1, 2, 3], [1, 2] ]
  
# Counts the number of times 'Cat' appears in list1
print(list1.count(('Cat', 'Bat')))
  
# Count the number of times sublist
# '[1, 2]' appears in list1
print(list1.count([1, 2]))

Output :

2
2

 

Practical Application :

Let’s say we want to count each element in a list and store in another list or say dictionary.




# Python3 program to count the number of times
# an object appears in a list using count() method 
  
lst = ['Cat', 'Bat', 'Sat', 'Cat', 'Mat', 'Cat', 'Sat']
  
# To get the number of occurrences 
# of each item in a list
print ([ [l, lst.count(l)] for l in set(lst)])
  
# To get the number of occurrences 
# of each item in a dictionary
print (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}

 

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