python中怎么對json串進行解析

本篇文章給大家分享的是有關python中怎么對json串進行解析，小編覺得挺實用的，因此分享給大家學習，希望大家閱讀完這篇文章后可以有所收獲，話不多說，跟著小編一起來看看吧。

現在有如下格式的json串：

“detail_time”:”2016-03-30 16:00:00”,”device_id”:”123456”,”os”:”Html5Wap”,”session_flow_id”:”1d1819f3-8e19-4597-b50d-ba379adcd8e5”,”user_longitude”:0.0000,”user_latitude”:0.0000,”search_id”:xxx,”search_guid”:-543326548,”search_type”:7,”AAA”:4,”BBB”:-1,”CCC”:[],”DDD”:3,”EEE”:2,”FFF”:1459267200,”GGG”:1459353600,”aaa”:90954603,”bbb”:[{“xxx”:1500848,”x”:1,”bf”:0,”pp”:2,”sroom”:2,”ppp”:108,”cost”:97.2,”coupon”:108,”drr”:108},{“xxx”:1500851,”x”:1,”bf”:0,”pp”:1,”sroom”:2,”ppp”:108,”cost”:97.2,”coupon”:108,”drr”:108},{“xxx”:2336691,”x”:1,”bf”:1,”pp”:1,”sroom”:3,”ppp”:199,”cost”:169.15,”coupon”:191,”drr”:199},{“xxx”:2336692,”x”:1,”bf”:1,”pp”:2,”sroom”:4,”ppp”:102,”cost”:91.8,”coupon”:102,”drr”:102},{“xxx”:1500848,”x”:1,”bf”:0,”pp”:2,”sroom”:3,”ppp”:118,”cost”:106.2,”coupon”:118,”drr”:118},{“xxx”:1500851,”x”:1,”bf”:0,”pp”:1,”sroom”:3,”ppp”:118,”cost”:106.2,”coupon”:118,”drr”:118},{“xxx”:2336693,”x”:1,”bf”:1,”pp”:1,”sroom”:5,”ppp”:199,”cost”:169.15,”coupon”:191,”drr”:199},{“xxx”:2336694,”x”:1,”bf”:1,”pp”:2,”sroom”:6,”ppp”:112,”cost”:100.3,”coupon”:112,”drr”:112},{“xxx”:1500848,”x”:1,”bf”:0,”pp”:2,”sroom”:1,”ppp”:98,”cost”:88.2,”coupon”:98,”drr”:98},{“xxx”:1500851,”x”:1,”bf”:0,”pp”:1,”sroom”:1,”ppp”:98,”cost”:88.2,”coupon”:98,”drr”:98},{“xxx”:2336687,”x”:1,”bf”:1,”pp”:1,”sroom”:1,”ppp”:189,”cost”:160.65,”coupon”:182,”drr”:189},{“xxx”:2336689,”x”:1,”bf”:1,”pp”:2,”sroom”:2,”ppp”:93,”cost”:83.3,”coupon”:93,”drr”:93},{“xxx”:1500848,”x”:1,”bf”:0,”pp”:2,”sroom”:4,”ppp”:128,”cost”:115.2,”coupon”:128,”drr”:128},{“xxx”:1500851,”x”:1,”bf”:0,”pp”:1,”sroom”:4,”ppp”:128,”cost”:115.2,”coupon”:128,”drr”:128},{“xxx”:2336695,”x”:1,”bf”:1,”pp”:1,”sroom”:7,”ppp”:239,”cost”:203.15,”coupon”:230,”drr”:239},{“xxx”:2336696,”x”:1,”bf”:1,”pp”:2,”sroom”:8,”ppp”:121,”cost”:108.8,”coupon”:121,”drr”:121}],”ppp_min”:93.00,”ppp_max”:239.00,”ppp_avg”:134.88,”ppp_med”:118.00,”ppp_min_cost”:83.30,”ppp_min_promotion_type”:-1,”ppp_min_promotion_amount”:-1,”bf_ppp_min”:149.00,”bf_ppp_min_cost”:83.30,”bf_ppp_min_promotion_type”:-1,”bf_ppp_min_promotion_amount”:-1}

現在想拿到device_id的具體值。最簡單的方式就是用解析json串的方式得到，代碼如下：

#!/usr/bin/env python
#coding:utf-8

import json
import sys
import collections
import time

def t1():
 start = time.clock()
 for line in sys.stdin:
  try:
   line = line.strip()
   decoded = json.loads(line)
   device_id = decoded["device_id"]
   print device_id
  except Exception,ex:
   pass

 end = time.clock()
 print "The cost time is: %f" %(end - start)

t1()

以上代碼能順利完成任務。

不幸的是，現在是大數據時代，數據量嘛，自然都很大。用了一萬條數據做測試，耗時達到了驚人的。。。將近10s。

轉換下思路，采用正則匹配的方式

#!/usr/bin/env python

import re
import sys
import time

def t1():
 start = time.clock()
 count = 0
 for line in sys.stdin:
  line = line.strip()
  pattern = re.compile("(?:\"device_id\":\")([^\"]+)")
  search = pattern.search(line)
  if search:
   count += 1
   #print search.groups()[0]
 end = time.clock()
 print "The count is: %d" %(count)
 print "The cost time is: %f" %(end - start)

t1()

注意匹配的時候

re.compile("(?:\"device_id\":\")([^\"]+)")

第一個分組表示不捕獲，只捕獲后面的分組。

同樣一萬條數據，運行耗時是。。。0.05s。效率提高了多少倍，表示算不過來了。

以上就是python中怎么對json串進行解析，小編相信有部分知識點可能是我們日常工作會見到或用到的。希望你能通過這篇文章學到更多知識。更多詳情敬請關注億速云行業資訊頻道。