Python Program to Search the Number of Times a Particular Number Occurs in a List

When it is required to search the frequency of a number in a list, Python provides multiple approaches. You can define a custom method, use the built-in count() method, or utilize dictionary-based counting with collections.Counter.

Method 1: Using Custom Function

Define a function that iterates through the list and counts occurrences ?

def count_num(my_list, x_val):
    my_counter = 0
    for elem in my_list:
        if (elem == x_val):
            my_counter = my_counter + 1
    return my_counter

my_list = [66, 26, 48, 140, 66, 20, 1, 96, 86]
print("The list is :")
print(my_list)
occ_number = 66
print('{} has occurred {} times'.format(occ_number, count_num(my_list, occ_number)))

The list is :
[66, 26, 48, 140, 66, 20, 1, 96, 86]
66 has occurred 2 times

Method 2: Using Built-in count() Method

The simplest approach is using the list's built-in count() method ?

my_list = [66, 26, 48, 140, 66, 20, 1, 96, 86]
occ_number = 66

count = my_list.count(occ_number)
print(f"The list is: {my_list}")
print(f"{occ_number} has occurred {count} times")

The list is: [66, 26, 48, 140, 66, 20, 1, 96, 86]
66 has occurred 2 times

Method 3: Using collections.Counter

For counting all elements at once, use Counter from the collections module ?

from collections import Counter

my_list = [66, 26, 48, 140, 66, 20, 1, 96, 86]
counter = Counter(my_list)

print(f"The list is: {my_list}")
print(f"All element frequencies: {dict(counter)}")
print(f"66 has occurred {counter[66]} times")

The list is: [66, 26, 48, 140, 66, 20, 1, 96, 86]
All element frequencies: {66: 2, 26: 1, 48: 1, 140: 1, 20: 1, 1: 1, 96: 1, 86: 1}
66 has occurred 2 times

Comparison

Conclusion

Use the built-in count() method for simple frequency counting. Use collections.Counter when you need to count frequencies of all elements simultaneously.