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Count frequencies of all elements in array in Python
In this tutorial, we are going to write a program that finds the frequency of all the elements in an array. We can find it in different ways let's explore two of them.
Using dict
Initialize the array.
Initialize an empty dict.
Iterate over the list.
If the element is not in dict, then set the value to 1.
Else increment the value by 1.
Print the element and frequencies by iterating over the dict.
Example
Let's see the code.
# intializing the list
arr = [1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3]
# initializing dict to store frequency of each element
elements_count = {}
# iterating over the elements for frequency
for element in arr:
# checking whether it is in the dict or not
if element in elements_count:
# incerementing the count by 1
elements_count[element] += 1
else:
# setting the count to 1
elements_count[element] = 1
# printing the elements frequencies
for key, value in elements_count.items():
print(f"{key}: {value}")Output
If you run the above program, you will get the following results.
1: 3 2: 4 3: 5
Let's see the second approach using Counter class of the collections module.
Using Counter class
Import the collections module.
Initialize the array.
Pass the list to the Counter class. And store the result in a variable.
Print the element and the frequencies by iterating over the result.
Example
See the code below.
# importing the collections module
import collections
# intializing the arr
arr = [1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3]
# getting the elements frequencies using Counter class
elements_count = collections.Counter(arr)
# printing the element and the frequency
for key, value in elements_count.items():
print(f"{key}: {value}")Output
If you run the above code, you will get the same output as previous one.
1: 3 2: 4 3: 5
Conclusion
If you have any doubts in the tutorial, mention them in the comment section.
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