Python仅将最后一行写入文件

Question

当我执行打印时，将显示所有文本，但是当写入文件时，仅写入最后一步。

 import json, urllib
from urllib import urlencode
import googlemaps
start = "Bridgewater, Sa, Australia"
finish = "Stirling, SA, Australia"

url = 'http://maps.googleapis.com/maps/api/directions/json?%s' % urlencode((
            ('origin', start),
            ('destination', finish)
 ))
ur = urllib.urlopen(url)
result = json.load(ur)

for i in range (0, len (result['routes'][0]['legs'][0]['steps'])):
    j = result['routes'][0]['legs'][0]['steps'][i]['html_instructions'] 
    print j
output = open("output.html", "w")
output.write(j)
output.close()

我也尝试过

   output.write("%s\n" %  j)

我得到一个错误，

   output.write(result['routes'][0]['legs'][0]['steps'][i]['html_instructions'])

仅显示最后一步

我想念什么？

Answer 1

那是因为您正在for循环之外写入文件，所以j仅包含最后一次迭代的值，因此您只将最后一行写入文件。

您应该改为在循环之前打开文件，然后在循环内部写入文件，也可以with语句一起使用来打开文件，以便自动处理关闭操作。 范例-

with open("output.html", "w") as output:
    for i in range (0, len (result['routes'][0]['legs'][0]['steps'])):
        j = result['routes'][0]['legs'][0]['steps'][i]['html_instructions'] 
        print j 
        output.write(j + '\n')

Answer 2

您只写最后一行，因为写操作在for循环之外：

with open("output.html", "w") as output:
   for step in result['routes'][0]['legs'][0]['steps']:
       print step['html_instructions'] 
       output.write(step['html_instructions']+'\n')