如何简化这个非常长的if语句？

Question

如何简化这个if语句？这是一个加号:http: //i.stack.imgur.com/PtHO1.png

如果语句完成,则在x和y坐标处设置块.

for y in range(MAP_HEIGHT):
    for x in range(MAP_WIDTH):
        if (x%5 == 2 or x%5 == 3 or x%5 == 4) and \
            (y%5 == 2 or y%5 == 3 or y%5 == 4) and \
            not(x%5 == 2 and y%5 == 2) and \
            not(x%5 == 4 and y%5 == 2) and \
            not(x%5 == 2 and y%5 == 4) and \
            not(x%5 == 4 and y%5 == 4):
            ...

Answer 1

这是一样的:

if (x % 5 == 3 and y % 5 > 1) or (y % 5 == 3 and x % 5 > 1): 

Answer 2

基本上你正在平铺5x5二进制模式.这里有一个明确的表达:

pattern = [[0, 0, 0, 0, 0],
           [0, 0, 0, 0, 0],
           [0, 0, 0, 1, 0],
           [0, 0, 1, 1, 1],
           [0, 0, 0, 1, 0]]

for y in range(MAP_HEIGHT):
    for x in range(MAP_WIDTH):
        if pattern[x%5][y%5]:
           ...

这是一种非常简单和通用的方法,可以轻松修改模式.

Answer 3

有两个简单的修复:

• 缓存结果x % 5和y % 5
• 使用in或链接<来测试值:

此外,用于测试<= 4(或< 5)实际上是多余的,因为每一个的值lx和ly将<5.

for y in range(MAP_HEIGHT):
    for x in range(MAP_WIDTH):
        lx = x % 5 # for local-x
        ly = y % 5 # for local-y
        if lx > 1 and y > 1 and \
           not (lx == 2 and ly == 2) and \
           not (lx == 4 and ly == 2) and \
           not (lx == 2 and ly == 4) and \
           not (lx == 4 and ly == 4):

或者你可以保留一个实际允许的元组列表:

cross_fields = [(2, 3), (3, 2), (3, 3), (3, 4), (4, 3)]

for y in range(MAP_HEIGHT):
    for x in range(MAP_WIDTH):
        if (x % 5, y % 5) in cross_fields: