Question

我觉得自己被困住了，非常感谢所有形式的帮助和指导。

我从yr.no（norweigan天气预报）下载了XML。它包含几个元素，包含一天中不同时间的天气报告。它每天有3个报告，但我只想使用其中一个报告，我想在接下来的7天打印出天气。到目前为止，我设法打印出所有日子的天气，或者只是一个。然而，我没有想过如何在错误的时间段内“理清”那些。

这是我最近尝试获得3份报告中的1份。每个报告都有三个要素，它们的独特之处在于它们的属性。我将在我的代码下面显示xml中的几行。如果你想下载整个xml来查看结构，我会在底部放一个链接。

我的最新尝试：

with open('Stockholm.xml', 'rt') as wreport:
    tree = ET.parse(wreport)

for temp in tree.getiterator("temperature"):
    counter = 2
    if counter == 0 or counter == 1:
        counter += 1
    elif counter == 2:
        counter -= 2
        print "In Stockholm it will today be %s celcius" % (temp.get("value"))

XML，我希望从名为“time”的前7个元素中得到元素“temperature”，得到句点=“2”：

<forecast>
 <tabular>
   <time from="2014-01-03T12:00:00" to="2014-01-03T18:00:00" period="2">
    <!--
    Valid from 2014-01-03T12:00:00 to 2014-01-03T18:00:00 
    -->
    <symbol number="4" name="Skya" var="04"/>
    <precipitation value="0.1" minvalue="0.1" maxvalue="0.2"/>
    <!--  Valid at 2014-01-03T12:00:00  -->
    <windDirection deg="163.3" code="SSE" name="Sør-søraust"/>
    <windSpeed mps="4.6" name="Lett bris"/>
    <temperature unit="celsius" value="4"/>
    <pressure unit="hPa" value="1007.0"/>
   </time>
<time from="2014-01-03T18:00:00" to="2014-01-04T00:00:00" period="3">...</time>
<time from="2014-01-04T00:00:00" to="2014-01-04T06:00:00" period="0">...</time>
<time from="2014-01-04T06:00:00" to="2014-01-04T12:00:00" period="1">...</time>

在所有这些中你可以获得我第一次展示的相同元素。点击此处下载链接：http://www.yr.no/stad/Sverige/Stockholm/Stockholm/varsel.xml

Answer 1

您应首先在'time'元素上迭代，以根据您的需要过滤它们。之后，您可以迭代“温度”子元素。像这样：

import lxml.etree as etree

with open('Stockholm.xml', 'rt') as wreport:
    xml = etree.parse(wreport)
    for record in xml.iter('time'):
        if record.attrib['period'] == '2':
            for temp in record.iter('temperature'):
                print 'In Stockholm it will today be %s celcius from %s to %s\n' %
                        (temp.attrib['value'], 
                        record.attrib['from'], 
                        record.attrib['to'])

或者，您可以像使用XPath一样使用XPath：

import lxml.etree as etree

with open('Stockholm.xml', 'rt') as wreport:
    xml = etree.parse(wreport)
        for temp in xml.findall('.//time[@period="2"]/temperature'):
            print 'In Stockholm it will today be %s celcius\n' % 
                            temp.attrib['value']

Answer 2

最近有模块 python-yr 可用它真的很容易使用。它从yr.no

提供JSON数据

检查出来：https://github.com/wckd/python-yr

示例：

#!/usr/bin/env python3

from yr.libyr import Yr
import dateutil.parser


weather = Yr( location_name='Czech_Republic/Central_Bohemia/Kralupy_nad_Vltavou', forecast_link='forecast', )

day_before=""  # days separator print line flag

for forecast in weather.forecast():

    day = dateutil.parser.parse(forecast['@from']).strftime("%A")

    if day_before != day:
        print()
        day_before = day


    time_from = dateutil.parser.parse(forecast['@from']).strftime("%d.%m.%Y %H:%M")

    time_to = dateutil.parser.parse(forecast['@to']).strftime("%H:%M%p")
    sky = forecast['symbol']['@name']
    wind = forecast['windSpeed']['@name']
    wind_speed = forecast['windSpeed']['@mps']
    precipitation = forecast['precipitation']['@value']
    temperature = forecast['temperature']['@value']
    print("{0:<7} {1}-{2}  {7:>2}°C  {3:<18}, wind {5:<4} m/s, prec.: {6:<3} mm ".format(
                    day,
                    time_from,
                    time_to,
                    sky,
                    wind,
                    wind_speed,
                    precipitation,
                    temperature))

如何通过其属性限制xml元素的循环？

2 个答案: