Python | Cumulative Columns summation of Records

Sometimes, while working with records, we can have a problem in which we need to sum all the columns of a container of lists which are tuples. This kind of application is common in web development domain. Let’s discuss certain ways in which this task can be performed. 
Method #1 : Using sum() + list comprehension + zip()
This task can be performed using combination of above functions. In this, we cumulate the like index elements, i.e columns using zip(), and then iterate through them using list comprehension and perform summation using sum().

Python3

# Python3 code to demonstrate working of
# Cumulative Columns summation of Records
# using list comprehension + sum() + zip()

# initialize list
test_list = [(1, 2, 3), (6, 7, 6), (1, 6, 8)]

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

# Cumulative Columns summation of Records
# using list comprehension + sum() + zip()
res =  [sum(ele) for ele in zip(*test_list)]

# printing result
print("The Cumulative column sum is : " + str(res))

Output

The original list : [(1, 2, 3), (6, 7, 6), (1, 6, 8)]
The Cumulative column sum is : [8, 15, 17]

The time complexity of the given Python code is O(n), where n is the number of elements in the input list. 

The auxiliary space complexity of the code is O(m), where m is the number of columns in the input list. 

Method #2 : Using zip() + map() + sum()
This method is similar to the above method. In this, the task performed by list comprehension is performed by map(), which extends the summation of columns to zipped elements.

Python3

# Python3 code to demonstrate working of
# Cumulative Columns summation of Records
# using zip() + map() + sum()

# initialize list
test_list = [(1, 2, 3), (6, 7, 6), (1, 6, 8)]

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

# Cumulative Columns summation of Records
# using zip() + map() + sum()
res = list(map(sum, zip(*test_list)))

# printing result
print("The Cumulative column sum is : " + str(res))

Output

The original list : [(1, 2, 3), (6, 7, 6), (1, 6, 8)]
The Cumulative column sum is : [8, 15, 17]

The time complexity of this code is O(n), where n is the number of tuples in the input list. 

The auxiliary space complexity of this code is O(m), where m is the length of each tuple in the input list. 

Method 3 – using a for loop:

 In this we method iterates through each column of the input list using the outer loop and calculates the sum of each column using the inner loop. The sum is then appended to the res list.

Python3

test_list = [(1, 2, 3), (6, 7, 6), (1, 6, 8)]

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

# Cumulative Columns summation of Records using for loop
res = []
for i in range(len(test_list[0])):
    col_sum = 0
    for j in range(len(test_list)):
        col_sum += test_list[j][i]
    res.append(col_sum)

# printing result
print("The Cumulative column sum is : " + str(res))

Output

The original list : [(1, 2, 3), (6, 7, 6), (1, 6, 8)]
The Cumulative column sum is : [8, 15, 17]

The time complexity of this program is O(n^2), where n is the number of rows or columns in the input list test_list. 

The auxiliary space used by this program is O(n), where n is the number of columns in the input list test_list.