python-2.7 - 如果列表索引超出范围，则打印

Question

大家好，我试图为“列表索引超出范围”创建一个句柄，但似乎没有任何运气。

import json, urllib, re
from urllib import urlencode
import googlemaps
import tempfile
import win32api
import win32print
start = "Adelaide, South Australia"
finish = " ghkjffzh, south Australia "



url = 'http://maps.googleapis.com/maps/api/directions/json?%s' % urlencode((
            ('origin', start),
            ('destination', finish)
 ))
ur = urllib.urlopen(url)
result = json.load(ur)
filename = "output.txt"
with open(filename, 'w') as output:
                for i in range(0, len(result['routes'][0]['legs'][0]['steps'])):
                    try:
                        s = (result['routes'][0]['legs'][0]['steps'][i]['html_instructions'])
                        d = (result['routes'][0]['legs'][0]['steps'][i]['distance']['text'])
                        l = (result['routes'][0]['legs'][0]['steps'][i]['duration']['text'])
                        s = re.sub('<[A-Za-z\/][^>]*>', '', s)
                        output.writelines(s + " " + d + " " + l + '\n')
                    except Exception:
                                print "Directions could not be printed"
                                output.write("Directions could not be given due to the format of page or the address type")

但没有任何内容写入.txt并仍然出现错误。

香港专业教育学院试图用IndexError和VauleError替换Exception但没有变化

Answer 1

通过探索返回的json结果来解决该问题，并找到一个Status结果，因此我首先通过了该结果。

with open(filename, 'w') as output: 
     if result ['status'] == "NOT_FOUND"
      output.write( " no directions avalible")
     else:
       for i in range(0, len(result['routes'][0]['legs'][0]['steps'])): 
          s = (result['routes'][0]['legs'][0]['steps'][i]['html_instructions']) 
          d = (result['routes'][0]['legs'][0]['steps'][i]['distance']['text']) 
          l = (result['routes'][0]['legs'][0]['steps'][i]['duration']['text'])
          s = re.sub('<[A-Za-z\/][^>]*>', '', s)
          output.writelines(s + " " + d + " " + l + '\n')