图片大小的相似度

def get_similar_size(sources, dsts):
    """
    输入sources，返回dsts中对应size接近的列表。其中 len(dsts) >= len(sources)

    数据类型：
    source: ["270*180", "25*45", "45*45", "45*45"]
    dst要保证有id,size属性。
    用例：
    source:["270*180", "25*45", "45*45", "45*45"]
    dst：{id:0, size:"270*270" }
    {id:1, size:"45*27" } 
    {id:2, size:"96*75" } 
    {id:3, size:"45*96" }
    {id:4, size:"15*32" } 
    {id:5, size:"340*320" }
    返回：
    {'id': 1, 'size': '45*27'}
    {'id': 3, 'size': '45*96'}
    {'id': 0, 'size': '270*270'}
    {'id': 5, 'size': '340*320'}
    时间复杂度：n*n
    """
    class Pic(object):
        def __init__(self,width,height):
            self.height = height
            self.width = width

    inner_sources = [Pic(int(x.split("*")[0]), int(x.split("*")[1])) for x in sources]
    inner_dsts_list = []
    for dst in dsts:
        temp_dst = Pic(int(dst.size.split("*")[0]), int(dst.size.split("*")[1]))
        temp_dst.id = dst.id
        inner_dsts_list.append(temp_dst)

    result_id = []
    for temp_inner_source in inner_sources:
        target = pic_size_most_similar(temp_inner_source, inner_dsts_list)
        result_id.append(target.id)
        inner_dsts_list.remove(target)

    result = []
    for id in result_id:
        result.append(_find_by_id(id, dsts))

    return result

def _find_by_id(id, target_list):
    for item in target_list:
        if id==item.id:
            return item

def pic_size_most_similar(source, dsts):
    """
    原理：无论目标图多大，把它等比缩放（扩大）到与原图等宽
    然后算出此时的高，求与原图高的差距，即可算出相似性
    返回大小最相似的图片
    时间复杂度： n
    """
    target = None
    mini_distance = 65535
    for dst in dsts:
        target_height = dst.height * source.width / float(dst.width)
        distance = abs(target_height - source.height)
        if distance < mini_distance:
            target = dst
            mini_distance = distance
    return target

class DbPics(object):
    def __init__(self):
        self.id = 0
        self.size = ""


sources = ["270*180", "25*45", "45*45", "45*45"] # width * height
test_data_dsts = ["270*270", "45*27", "96*75", "45*96", "15*32","340*320"]

dsts = []
for k,v in enumerate(test_data_dsts):
    temp_dst = DbPics()
    temp_dst.id = k
    temp_dst.size = v
    dsts.append(temp_dst)

result = get_similar_size(sources, dsts)
for item in result:
    print item.__dict__

{'id': 1, 'size': '45*27'}
{'id': 3, 'size': '45*96'}
{'id': 0, 'size': '270*270'}
{'id': 5, 'size': '340*320'}