The Python Counter class from the collections module is a powerful tool that we can also use for counting the occurrences of elements in a list.
Let us say that we have a list like the following and want to count the number of times each element appears in there:
my_list = [1, 2, 3, 2, 2, 2, 2]
Now we can simply call the constructor of Counter and put that list inside it:
from collections import Counter
my_list = [1, 2, 3, 2, 2, 2, 2]
result = Counter(my_list)
print(result) # Counter({2: 5, 1: 1, 3: 1})
In the example above, we create a Counter object using a list of integers. The resulting Counter object shows that the number 2 appears 5 times, the number 1 appears once, and the number 3 appears once.
We can access the frequencies of the elements using the most_common() method. This method returns a list of tuples, where each tuple consists of an element and its frequency. The list is ordered by the frequencies in descending order:
print(result.most_common()) # [(2, 5), (1, 1), (3, 1)]
In the example above, the most_common() method returns [(2, 5), (1, 1), (3, 1)], which means that the element 2 appears 5 times, the element 1 appears 1 time, and the element 3 appears 1 time.
Here is the complete example:
from collections import Counter
my_list = [1, 2, 3, 2, 2, 2, 2]
result = Counter(my_list)
print(result) # Counter({2: 5, 1: 1, 3: 1})
print(result.most_common()) # [(2, 5), (1, 1), (3, 1)]
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