我要索引超出列表错误

Question

def calcDistance(x1, y1, x2, y2): 
    distance = sqrt((x1-x2)**2 + (y1-y2)**2) 

    return distance 

def make_dict(): 
    return defaultdict(make_dict) 

# Capture 1 input from the command line. 
# NOTE: sys.argv[0] is the name of the python file 
# Try "print sys.argv" (without the quotes) to see the sys.argv list 
# 1 input --> the sys.argv list should have 2 elements. 
if (len(sys.argv) == 2): 
    print "\tOK. 1 command line argument was passed." 

    # Now, we'll store the command line inputs to variables 
    myFile = str(sys.argv[1]) 
else: 
    print 'ERROR: You passed', len(sys.argv)-1, 'input parameters.' 
    quit() 


# Create an empty list: 
cities = [] 

# Create an empty dictionary to hold our (x,y) coordinate info: 
myCoordinates = {} 

# Open our file: 
myFile = '%s.csv' % (myFile) 
with open(myFile, 'rb') as csvfile: 
    spamreader = csv.reader(csvfile, delimiter=',', quotechar='|') 
    for row in spamreader: 
     # Only read rows that do NOT start with the "%" character. 
     if (row[0][0] != '%'): 
      # print row 
      id = int(row[0]) 
      isHome = int(row[1]) 
      x = float(row[2]) 
      y = float(row[3]) 

      myCoordinates[id] = {'x': x, 'y': y} 
      # print myCoordinates[id]['x'] 
      # print myCoordinates[id]['y'] 


      if (isHome == 1): 
       # Store this id as the home city 
       homeCity = id 

      cities.append(id)   

print homeCity 
print cities 

# Create a TSP tour. 
# VERSION 1 -- Using range() and for() loops: 

myTour = [] 
for i in range(homeCity, len(cities)+1): 
    myTour.append(i) 
for i in range(1, homeCity+1): 
    myTour.append(i)  
print myTour 

# VERSION 2 -- Using only range() 
''' 
firstPart = range(homeCity, len(cities)+1) 
secondPart = range(1, homeCity+1) 
myTour = firstPart + secondPart 
print myTour 
''' 

tau = defaultdict(make_dict) 

for i in cities: 
    # print "distance[%d][%d] = 0" % (i, i) 
    tau[i][i] = 0 
    for j in range(i+1, len(cities)+1):   
     # print "distance[%d][%d] > 0" % (i, j) 
     tau[i][j] = calcDistance(myCoordinates[i]['x'], myCoordinates[i]['y'], myCoordinates[j]['x'], myCoordinates[j]['y']) 
     # print "distance[%d][%d] = distance[%d][%d]" % (j, i, i, j) 
     tau[j][i] = tau[i][j] 


# FIXME -- Edit the code below... 
# Calculate the total distance of our TSP solution: 
i = myTour[i] 
for myIndex in range(1, len(myTour)+1): 
    j = myTour[myIndex] 
    print j 

基于距离计算成本的函数。需要修改。

def cost(rate,j): 
    cost = rate * j 
cost = cost(1000,j) 
print cost 

另外我需要根据行驶距离计算成本。与myIndex我得到一个错误list index out of range。我不知道那里究竟发生了什么。 j就像计算的总距离。

Answer 1

python中的列表有0个索引。如果将n个元素添加到列表中，索引是从0到n-1。但是您正在运行从1到n的循环。所以，它变得list index out of range错误。

你应该做这 -

for myIndex in range(0, len(myTour)): 
    j = myTour[myIndex] 
    print(j) 

如果您收到list index out of range错误，那么改变你在哪里得到的错误，并使用基于1的索引，从range(1,len(some_list)+1)到range(0,len(some_list))访问list循环。或者你可以简单地写range(len(some_list))。当范围函数中没有传入起始值时，默认从0开始。

要计算cost试试这个 -

for myIndex in range(0, len(myTour)): 
    j = myTour[myIndex] 
    cost = rate * j 
    print(cost) 

开始循环之前设置的rate值。