Python List Function | count ()

Python Methods and Functions

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 for counting the number of times
# object appears in the list with using the count () method

 

list1 = [ 1 , 1 , 1 , 2 , 3 , 2 , 1

 
# Counts how many times 1 appears in list 1

print (list1.count ( 1 )) 

 

list2 = [ 'a' , 'a' , ' a' , 'b' , ' b' , 'a' , ' c' , 'b'

 
# Counts how many times “b” appears in the list

print (list2.count ( 'b ' )) 

  

list3 = [ 'Cat' , 'Bat' , ' Sat' , 'Cat' , 'cat' , ' Mat' ]

 
# Counts how many times & # 39; Cat & # 39; appears in list 3

print (list3.count ( ' Cat' ))

Output:

 4 3 2 

Code # 2: TypeError

# Python3 demo
# error in count () method

 

list1 = [ 1 , 1 , 1 , 2 , 3 , 2 , 1

 
# Error passing two parameters.

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
# object appears in the list using the count () method

  

list1 = [ ( 'Cat' , ' Bat' ), ( 'Sat' , ' Cat' ), ( 'Cat' , 'Bat' ),

  ( 'Cat' , ' Bat' , 'Sat' ), [ 1 , 2 ], [ 1 , 2 , 3 ], [ 1 , 2 ]]

 
# Counts how many times "Cat" appears in the list

print (list1.count (( 'Cat' , 'Bat' )))

  
# Count the number of times sublisted
# & # 39; [1, 2] & # 39; appears in list 1

print (list1.count ([ 1 , 2 ]))

Output:

 2 2 

Practical Application:

Let's say we want to count each item in a list and store in another list, or say a dictionary.

# Python3 program for counting the number of times
# object appears in the list using the count () method

 

lst = [ 'Cat' , ' Bat' 'Sat' , ' Cat' , 'Mat' , ' Cat' , 'Sat' ]

 
# To see the number of occurrences
# of each item in the list

print ([[l, lst.count (l)] for l in set (lst)])

 
# To see the number of occurrences
# of each item in the 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}