Python 3 : Getting information from list in list

Question

我在 Python 3 中有这样的 txt 文件(城市只是示例):

Tokyo 0 267 308 211 156 152 216 27 60 70 75
London 267 0 155 314 111 203 101 258 254 199 310
Paris 308 155 0 429 152 315 216 330 295 249 351
Vienna 211 314 429 0 299 116 212 184 271 265 252
Tallinn 156 111 152 299 0 183 129 178 143 97 199
Helsinki 152 203 313 116 183 0 99 126 212 151 193
Stockholm 216 101 216 212 129 99 0 189 252 161 257
Moscow 27 258 330 184 178 126 189 0 87 73 68
Riga 60 254 295 271 143 212 252 87 0 91 71
Melbourne 70 199 249 265 97 151 161 73 91 0 128
Oslo 75 310 351 252 199 193 257 68 71 128 0

我想让程序像这样工作，例如:

Please enter starting point: Paris
Now please enter ending point: Riga
Distance between Paris and Riga is 295 km.

我对Python相当陌生，我不知道如何读取列表中的距离列表。到目前为止我所做的事情:

cities = [] 
distances = []

file = open("cities.txt")

for city_info in file:
city_info = city_info.strip()
city = city_info.split()        
cities.append(city[0])

distances2 = []
for dist in city[1:]:
    distances2.append(int(dist))   
distances.append(distances2)

# to check, if lists are good to go

print(distances)
print(cities)

file.close()

amount = len(cities)

for x in range(amount):
    for y in range(amount):
        startpoint = cities[x]
        endpoint = cities[y]
        dist1 = distances[x][y]

    startpoint = input("Enter start point: ").capitalize()
    if startpoint not in cities:
        print("Start point doesn't exist in our database: ", startpoint)
    else:
        endpoint = input("Enter end point: ").capitalize()
        if endpoint not in cities:
            print("Start point doesn't exist in our database: ", endpoint)
        else:
            print("Distance between", startpoint, "and", endpoint, "is", dist1, "kilometers.")

由于我对Python语言不太熟悉，所以我不知道我做错了什么。

例如，我想获取城市[1]和城市[4]之间的距离，因此它应该从距离[1][4]找到距离。

Answer 1

试试这个:

# reading from file:
with open('cities.txt') as f:
    lines = f.readlines()

# pre-processing
indices = {line.split()[0]: i for i, line in enumerate(lines)}
distances = [line.split()[1:] for line in lines]

#user input:
start = input("Please enter starting point: ")
end = input("Now please enter ending point: ")

# evaluation:
distance = distances[indices[start]][indices[end]]

# output:
print("Distance between {start} and {end} is {distance} km.".format(**locals()))