(Sum elements column by column) Python Question

Question

Write a function that returns the sum of all the elements in a specified column in a matrix using the following header:

def sumColumn(m, columnIndex):

Write a test program that reads a 3 × 4 matrix and displays the sum of each column. Note that the matrix is entered by rows and the numbers in each row are separated by a space in one line.

Answer 1

Try something like this:

def sumColumn(m, columnIndex):

s = 0

for i in range(len(m)):

s += m[i][columnIndex]

return s

You can also do it with list comprehension:

def sumColumn(m, columnIndex):

return sum([row[columnIndex] for row in m])

Hope this helps, and I'll leave the test program up to you.