Python list function | count()

** 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 aTypeError.

**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}

Attention geek! Strengthen your foundations with the **Python Programming Foundation** Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the **Python DS** Course. And to begin with your Machine Learning Journey, join the **Machine Learning – Basic Level Course**