使用BeautifulSoup循环HTML标记

Question

正如前面提到的问题所提到的，我正在使用带有python的Beautiful soup来从网站上检索天气数据。

以下是网站的外观：

<channel>
<title>2 Hour Forecast</title>
<source>Meteorological Services Singapore</source>
<description>2 Hour Forecast</description>
<item>
<title>Nowcast Table</title>
<category>Singapore Weather Conditions</category>
<forecastIssue date="18-07-2016" time="03:30 PM"/>
<validTime>3.30 pm to 5.30 pm</validTime>
<weatherForecast>
<area forecast="TL" lat="1.37500000" lon="103.83900000" name="Ang Mo Kio"/>
<area forecast="SH" lat="1.32100000" lon="103.92400000" name="Bedok"/>
<area forecast="TL" lat="1.35077200" lon="103.83900000" name="Bishan"/>
<area forecast="CL" lat="1.30400000" lon="103.70100000" name="Boon Lay"/>
<area forecast="CL" lat="1.35300000" lon="103.75400000" name="Bukit Batok"/>
<area forecast="CL" lat="1.27700000" lon="103.81900000" name="Bukit Merah"/>` 
..
..
<area forecast="PC" lat="1.41800000" lon="103.83900000" name="Yishun"/>
<channel>

我设法使用这些代码检索我需要的信息：

import requests
from bs4 import BeautifulSoup
import urllib3
import csv
import sys
import json

#getting the Validtime

area_attrs_li = []

r = requests.get('http://www.nea.gov.sg/api/WebAPI/?    
dataset=2hr_nowcast&keyref=781CF461BB6606AD907750DFD1D07667C6E7C5141804F45D')
soup = BeautifulSoup(r.content, "xml")
time = soup.find('validTime').string
print "validTime: " + time

#getting the date

for currentdate in soup.find_all('item'):
 element = currentdate.find('forecastIssue')
 print "date: " + element['date']

#getting the time

for currentdate in soup.find_all('item'):
 element = currentdate.find('forecastIssue')
 print "time: " + element['time'] 

#print area

for area in soup.select('area'): 
 area_attrs_li.append(area)
 print area

#print area name

areas = soup.select('area')
for data in areas:
    name = (data.get('name'))
    print name

f = open("C:\\scripts\\testing\\testingnea.csv" , 'wt')

try:
  for area in area_attrs_li:
   #print str(area) + "\n"
   writer = csv.writer(f)
   writer.writerow( (time, element['date'], element['time'], area, name))

finally:
  f.close()

print open("C:/scripts/testing/testingnea.csv", 'rt').read()

我设法以CSV格式获取数据，但是当我运行这部分代码时：

#print area name

areas = soup.select('area')
for data in areas:
    name = (data.get('name'))
    print name

结果如下：

显然，我的循环不起作用，因为它一遍又一遍地打印最后一个记录的最后一个区域。

编辑：我尝试循环浏览列表中的区域数据：

for area in area_attrs_li:
    name = (area.get('name'))
    print name

然而，它仍然没有循环。

我不确定代码出错的地方：/

Answer 1

问题在于：writer.writerow( (time, element['date'], element['time'], area, name))，name永远不会改变。

解决问题的方法：

try:
    for index, area in enumerate(area_attrs_li):
        # print str(area) + "\n"
        writer = csv.writer(f)
        writer.writerow((time, element['date'], element['time'], area, areas[index].get('name')))
finally:
    f.close()

Answer 2

这是因为在你写作时，你指的是循环的最后一个例子，试试这个：

writer.writerow( (time, element['date'], element['time'], area, area['name']))

Answer 3

在循环之后，您只在name变量中获得一个值。你需要一个清单。试试这个

areas = soup.select('area')
name=[]
for data in areas:
    name.append(data.get('name'))
    print name
l=len(name)

并在最后尝试

i=0
try:
    for area in area_attrs_li:
        writer = csv.writer(f)
        writer.writerow( (time, element['date'], element['time'], area, name[i]))
        i=i+1