链码的起点归一化、循环归一化、边界的长度、直径、形状数代码实现

链码的起点归一化：

def normalize_start_point(chain_code):
    # 计算链码所在位置
    min_x = min_y = sys.maxsize
    for code in chain_code:
        x, y = code_to_coordinate(code)
        if x < min_x:
            min_x = x
        if y < min_y:
            min_y = y
    # 将链码起点平移到(0,0)位置
    normalized_code = []
    for code in chain_code:
        x, y = code_to_coordinate(code)
        normalized_code.append(coordinate_to_code(x - min_x, y - min_y))
    return normalized_code

循环归一化：

def normalize_loop(chain_code):
    # 首先进行起点归一化
    normalized_code = normalize_start_point(chain_code)
    # 找到最小的循环表示法
    min_code = normalized_code[:]
    for i in range(len(normalized_code)):
        code = normalized_code[i:] + normalized_code[:i]
        if code < min_code:
            min_code = code
    return min_code

边界的长度：

def boundary_length(chain_code):
    length = 0
    for code in chain_code:
        if code % 2 == 0:
            length += 1
        elif code % 4 == 1:
            length += math.sqrt(2)
        else:
            length += 1 + math.sqrt(2)
    return length

直径：

def diameter(chain_code):
    max_distance = 0
    for i in range(len(chain_code)):
        for j in range(i+1, len(chain_code)):
            distance = code_distance(chain_code[i], chain_code[j])
            if distance > max_distance:
                max_distance = distance
    return max_distance

形状数：

def shape_number(chain_code):
    # 首先进行起点归一化
    normalized_code = normalize_start_point(chain_code)
    # 计算转角数
    corner_count = 0
    for i in range(1, len(normalized_code)):
        if abs(normalized_code[i] - normalized_code[i-1]) > 1:
            corner_count += 1
    # 计算形状数
    shape_count = (corner_count - 4) / 4
    return shape_count