CODEWITHSUNDEEP
pythonlistmatrix2d
user14221871
user14221871

Reputation:

Finding the sum of column of all the rows in a matrix without using numpy

This is my code to find the sum of all the elements of all columns in a given matrix:

row, col = map(int, input().split())
mat1 = [list(map(int, input().split())) for i in range(row)]

result = 0

j = 0
for i in range(row):
    result += mat1[i][j]

print(result)

I am able to get the answer for the first column but I am unable to do it for other columns. Where should I increment j to +1 to get the result for other columns?

This is the input:

2 2
5 -1
19 8

This is the output:

24
7

I got 24 as the answer. How should I get 7 now?

EDIT:

Can I insert the code in a function? After I got the first column's answer, I can increment j outside the loop and then call the function? I think it is known as recursion. I don't know I am new to programming

Upvotes: 2

Views: 515

Answers (2)

Pouya Esmaeili
Pouya Esmaeili

Reputation: 1263

You should define loop on columns (you have used a fixed value j) and call your code for each column as this:

row, col = map(int, input().split())
mat1 = [list(map(int, input().split())) for i in range(row)]

def sum_column(mat1, row, j):
    result = 0 #initialize
    for i in range(row): #loop on rows
        result += mat1[i][j]
    return result

for j in range(col): #loop on columns
    #call function for each column
    print(f'Column {j +1} sum: {sum_column(mat1, row, j)}')

UPDATE: please pay attention to the way you get input from user. Although the function is applied on col but in your code user can define more columns than col. You can ignore extra columns like this:

mat1 = [list(map(int, input().split()[:col])) for i in range(row)]

Upvotes: 0

Mihai Alexandru-Ionut
Mihai Alexandru-Ionut

Reputation: 48337

You should use another for loop for j and reinitialize the result when a new column started to be processed.

for j in range(col):
   result = 0
   for i in range(row):
       result += mat1[i][j]
   print(result)

Can I insert the code in a function? After I got the first column's answer, I can increment j outside the loop and then call the function? I think it is known as recursion.

Yes, you can do this with recursion.

matrix = [[5, -1], [19, 8]]
row = 2
column = 2

def getResult(j, matrix, result):
   if j >= column:
      return result
   s = sum([matrix[i][j] for i in range(row)])
   result.append(s)
   return getResult(j + 1, matrix, result)

result = getResult(0, matrix, [])

Output

> result
[24, 7]

Upvotes: 2

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