如何从 for in 循环 ( Python ) 中获取第一个 url

Question

I try to get the first link from dataInfo from the loop. This script make it possible for me to get image links and to download the image files. I want only the first image not all, thats my problem.

# Get results using JSON
results = simplejson.load(response)
data = results['responseData']
dataInfo = data['results']

# Iterate for each result and get unescaped url
for myUrl in dataInfo:
    count = count + 1
    print myUrl['unescapedUrl']

    myopener.retrieve(myUrl['unescapedUrl'],str(count)+'.jpg')

here is the whole source code

  import os
import sys
import time
from urllib import FancyURLopener
import urllib2
import simplejson

# Define search term
searchTerm = "intel i7"

# Replace spaces ' ' in search term for '%20' in order to comply with request
searchTerm = searchTerm.replace(' ','%20')


# Start FancyURLopener with defined version 
class MyOpener(FancyURLopener): 
    version = 'Mozilla/5.0 (Windows; U; Windows NT 5.1; it; rv:1.8.1.11) Gecko/20071127 Firefox/2.0.0.11'
myopener = MyOpener()

# Set count to 0
count= 0

for i in range(0,10):
    # Notice that the start changes for each iteration in order to request a new set of images for each loop
    url = ('https://ajax.googleapis.com/ajax/services/search/images?' + 'v=1.0&q='+searchTerm+'&start='+str(i*4)+'&userip=MyIP')
    print url
    request = urllib2.Request(url, None, {'Referer': 'testing'})
    response = urllib2.urlopen(request)

    # Get results using JSON
    results = simplejson.load(response)
    data = results['responseData']
    dataInfo = data['results']

    # Iterate for each result and get unescaped url
    for myUrl in dataInfo:
        count = count + 1
        print myUrl['unescapedUrl']

        myopener.retrieve(myUrl['unescapedUrl'],str(count)+'.jpg')

    # Sleep for one second to prevent IP blocking from Google
    time.sleep(1)

Answer 1

获得图像后，尝试 break 在 for 循环的第一次迭代后转义。例如，

for myUrl in dataInfo:
    count = count + 1
    print myUrl['unescapedUrl']
    myopener.retrieve(myUrl['unescapedUrl'],str(count)+'.jpg')
    break

Answer 2

你可以for myUrl in dataInfo[:1]:

或在您成功下载第一个图像后中断：

for myUrl in dataInfo:
  count = count + 1
  print myUrl['unescapedUrl']
  try:
    myopener.retrieve(myUrl['unescapedUrl'],str(count)+'.jpg')
    break
  except:
    pass

Answer 3

需要说明的是，此处的 dataInfo 包含一个 URL 列表，您只需要第一个。对吗？

如果是这样，您应该能够简单地引用第一个（第 0 个）索引，而不是循环遍历 dataInfo。

而不是

for myUrl in dataInfo:
    count = count + 1
    print myUrl['unescapedUrl']

    myopener.retrieve(myUrl['unescapedUrl'],str(count)+'.jpg')

然后您应该可以使用

myopener.retrieve(dataInfo[0]['unescapedUrl'],'0.jpg')

Answer 4

dataInfo[0]['unescapedUrl']

应该是第一个url

如何从 for in 循环 ( Python ) 中获取第一个 url

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