Python | Percentage occurrence at index

Sometimes while dealing with statistics, we might come across this particular problem in which we require to find the percentage of occurrence of element at particular index in list of list. Let’s discuss certain ways in which this can be done.

Method #1 : Using loop + list comprehension
We can perform this particular task using the loop for each list index, and for that we can compute the percentage occurrence of element using the list comprehension logic.

# Python3 code to demonstrate
# index percentage calculation of element
# using loop + list comprehension

# initializing test list
test_list = [[3, 4, 5], [2, 4, 6], [3, 5, 4]]

# printing original list
print("The original list : " + str(test_list))

# using loop + list comprehension
# index percentage calculation of element
res = []
for i in range(len(test_list[1])):
    res.append(len([j[i] for j in test_list if j[i]== 4 ])/len(test_list))

# print result
print("The percentage of 4 each index is : " + str(res))

Output :

The original list : [[3, 4, 5], [2, 4, 6], [3, 5, 4]]
The percentage of 4 each index is : [0.0, 0.6666666666666666, 0.3333333333333333]

Method #2 : Using zip() + count() + list comprehension
This particular task can also be performed using the combination of above functions. The count and zip function do the task of percentage computation and grouping respectively.

# Python3 code to demonstrate
# index percentage calculation of element
# using zip() + count() + list comprehension

# initializing test list
test_list = [[3, 4, 5], [2, 4, 6], [3, 5, 4]]

# printing original list
print("The original list : " + str(test_list))

# using zip() + count() + list comprehension
# index percentage calculation of element
res = [sub.count(4)/len(sub) for sub in zip(*test_list)]

# print result
print("The percentage of 4 each index is : " + str(res))

Output :

The original list : [[3, 4, 5], [2, 4, 6], [3, 5, 4]]
The percentage of 4 each index is : [0.0, 0.6666666666666666, 0.3333333333333333]