Question

Recall the function definition of creating a 2D list representing a screen of pixels: def create_screen(rows, columns): ''' Creates a screen of rows x columns pixels ''' grid = [] for x in range(rows): grid.append([0] * columns) return grid Complete the following function definition according to the docstring comment and assert examples below: def count_pixels(screen): ''' The parameter screen has arbitrary values and dimension (represented as a 2D list). Return the number of pixels with a value equal to 0. '''

Answer 1

def create_screen(rows, columns):
    """ Creates a screen of rows x columns pixels """
    grid = []
    for x in range(rows):
        grid.append([0] * columns)
    return grid


def count_pixels(screen):
    """ The parameter screen has arbitrary values and dimension (represented as a 2D list). Return the number of 
    pixels with a value equal to 0. """
    count = 0
    for row in screen:
        for item in row:
            if item == 0:
                count += 1
    return count