我有一些麻烦,变量被设置为相同的时候,他们不应该是,我不明白为什么他们这样做。在我的例子中,LCT和MCT被设置为函数中生成的最后一个路由,但是我只在路由分别小于或大于最小成本或最大成本时才设置它们。基本上,我正在创建一个0-13之间的整数的伪随机列表作为城市标签,并使用I-by-j数组查找查找它们之间的距离,其中值表示从城市I到城市j的距离。这是我的TSP项目的一部分。以下是一些代码供参考:
import random
def distance(x1, y1, x2, y2):
"""
Finds the distance between two points with coordinates (x1, y1) and (x2, y2)
:param x1: x-coordinate of first point
:type x1: float or int
:param y1: y-coordinate of first point
:type y1: float or int
:param x2: x-coordinate of second point
:type x2: float or int
:param y2: y-coordinate of second point
:type y2: float or int
:return: distance between two points
:rtype: float
"""
return (((x2-x1)**2) + ((y2-y1)**2)) ** 0.5
def shuffle(idxs):
"""
Performs random swaps n times with random seeded generator
:param idxs: Set of items to choose from
:type idxs: list, tuple, or dict
:return: modified idxs
:rtype modified idxs: type(idxs)
"""
n = 32
for k in range(n):
random.seed()
a, b = random.randint(0, 13), random.randint(0, 13)
swap(idxs, a, b)
# print(idxs)
return idxs
def swap(mylist, a, b):
"""
Swaps two values
:param mylist: order of things to choose from
:type mylist: list, tuple, or dict
:param a: first index
:type a: list/tuple: int; dict: key
:param b: second index
:type b: list/tuple: int; dict: key
:return: none; edits items in place
"""
temp = mylist[a]
mylist[a] = mylist[b]
mylist[b] = temp
mat = [[0.430796749, 0.660341257],
[0.869607109, 0.145710154],
[0.272249997, 0.281035268],
[0.310050105, 0.717362826],
[0.847481151, 0.505130257],
[0.054921944, 0.597324847],
[0.565507064, 0.578311901],
[0.578311901, 0.636552793],
[0.170565332, 0.160881561],
[0.800726237, 0.384045138],
[0.622627218, 0.957622127],
[0.608021461, 0.736718151],
[0.628737267, 0.622146623],
[0.665929436, 0.720342005]]
distances = [[distance(x1=mat[i][0], y1=mat[i][1],
x2=mat[j][0], y2=mat[j][1]) for j in range(14)] for i in range(14)]
route = [i for i in range(14)]
bigN = 1000
LC = 100
MC = 0
for j in range(bigN):
this_dist = 0
route = shuffle(route)
# print('Route:', route)
# Get the distance for the route
for stop in range(len(route)):
if stop != len(route) - 1: # if its not the last node
this_dist += distances[route[stop]][route[stop + 1]]
else: # Add cost from last item to first item
this_dist += distances[route[stop]][route[0]]
# print('Distance:', this_dist)
# Update min/max
if this_dist < LC:
LC = this_dist
LCT = route
print('New low:', LCT, 'Distance:', LC)
elif this_dist > MC:
MC = this_dist
MCT = route
print('New high:', MCT, 'Distance:', MC)
print('Last route:', route, 'Last distance:', this_dist)
# Output
print('Least cost:', LC)
print('Least cost trip:', LCT)
print('Most cost:', MC)
print('Most cost trip:', MCT)
如果你把它复制粘贴到IDE中并运行它,你就会明白我的意思。LCT和MCT被设置为生成的最后一条路线(即使它不是最低/最高成本的旅行),而我只在当前路线比当前最低/最高成本的路线短/长时才更改它们。为什么会发生这种情况?我该怎么做才能将其正确设置为LCT/MCT?我很困惑,如果这是一个很长的职位,很抱歉,但我不能明白这一点。如果有帮助的话,我使用的是python3.7。编辑:问题澄清。你知道吗
我希望LCT/MCT至少会有所不同,因为它们会有不同的路线和不同的距离。我的问题是,变量被设置为最后生成的路由,不管它是否比实际的最短/最长路由短/长。每次当前路线比实际的最短/最长路线短/长时,我都让它打印出新路线和新的最短距离。LCT/MCT应设置为最后一个打印出来的。你知道吗
最后一次编辑:jasonharper在评论中的解决方案有效(抱歉,如果我破坏了用户名,你在编辑模式下看不到它们,我没有足够的代表发表评论)。当我把它们复制到LCT/MCT时,我只需要在路由的末尾加上[:]。谢谢!你知道吗
基本上路线是可变的,每次都会改变。设置LCT/MCT时,它是指向路由的指针。您可以使用@jasonharper的建议并按如下方式更新代码:
相关问题 更多 >
编程相关推荐