# scale.py, by chaynes@indiana.edu

import image
    
def scale_length(lst, length):
    """Return a horizontally-scaled version of a list,
    stretched or compressed to be of the given length.

    >>> scaleLength([0, 1, 2], 6)
    [0, 0, 1, 1, 2, 2]
    >>> scaleLength([0, 1, 2, 3, 4, 5], 3)
    [0, 2, 4]
    >>>
    """
    answer = []
    for i in range(length):
        answer.append(lst[i * len(lst) / length])
    return answer

def scale_matrix_width(matrix, width):
    """Return matrix obtained from the given matrix by scaling each row
    to the given width.
    """
    answer = []
    for index in range(len(matrix)):
        row = matrix[index]
        answer.append(scale_length(row, width))
    return answer

def main():
    """Show bonsai.jpg with normal, expanded and compressed width."""
    m = image.read('bonsai.jpg')
    width = len(m[0])
    narrow = scale_matrix_width(m, width / 2)
    image.new(narrow).show()
    wide = scale_matrix_width(narrow, width * 2)
    image.new(wide).show()
    
if __name__ == '__main__':
    main()