Chapter9_Part7_3.py

# Part 7: Programming (PART 3)

# Initialize an array quantity:
quantity = [[2, 4,  3, 6, 9],
            [5, 8, 9, 3, 7],
            [1, 4, 3, 2, 10]]

# Additional function to print the array in a matrix format:
def prt(array):
    for a in array:
        print(a)

print("This is the original quantity matrix:")
prt(quantity)
print()

# Function that (1) takes the matrix (matrix), rows (r), columns(c), and row number (r_num) then, 
# (2) reverse that row number in the matrix.
def func(matrix, c, r_num):
    for i in range(0, c//2):         # For every value in a row, from 0 to the middle *NOTE 
        # The following reverses the values,
        # the first with the last, the second with the pre-last, and so on...
        temp = matrix[r_num][i]
        matrix[r_num][i] = matrix[r_num][c-1-i]
        matrix[r_num][c-1-i] = temp
        # *NOTE: when swaping, we are modifying the values from and also from the back,
        # so, when we are in the half-way, the task it's already done.
        # The operation //2 divides per 2, and truncates the decimal (this is taking the half list) 

# Altering the matrix with func
func(quantity, 5, 1)

print("This is the quantity matrix with the row reversed:")
prt(quantity)