2

我正在尝试使用欧元汇率解析来自欧洲中央银行的 XML 文件。不幸的是，我无法解析 XML 文件。当我删除困难的部分（与“gesmes”相关的所有内容）时，迭代“Cube”元素没有问题，但我无法处理 xml 文件的“gesmes”部分。我为此使用了 ElementTree API。

示例 XML 文件： http: //www.ecb.int/stats/eurofxref/eurofxref-daily.xml

<?xml version="1.0" encoding="UTF-8"?>
<gesmes:Envelope xmlns:gesmes="http://www.gesmes.org/xml/2002-08-01" xmlns="http://www.ecb.int/vocabulary/2002-08-01/eurofxref">
    <gesmes:subject>Reference rates</gesmes:subject>
    <gesmes:Sender>
        <gesmes:name>European Central Bank</gesmes:name>
    </gesmes:Sender>
    <Cube>
        <Cube time='2013-06-21'>
            <Cube currency='USD' rate='1.3180'/>
            <Cube currency='JPY' rate='128.66'/>
            <Cube currency='BGN' rate='1.9558'/>
            <Cube currency='CZK' rate='25.825'/>
            <Cube currency='DKK' rate='7.4582'/>
            <Cube currency='GBP' rate='0.85330'/>
            <Cube currency='HUF' rate='298.87'/>
            <Cube currency='LTL' rate='3.4528'/>
            <Cube currency='LVL' rate='0.7016'/>
            <Cube currency='PLN' rate='4.3289'/>
            <Cube currency='RON' rate='4.5350'/>
            <Cube currency='SEK' rate='8.6927'/>
            <Cube currency='CHF' rate='1.2257'/>
            <Cube currency='NOK' rate='7.9090'/>
            <Cube currency='HRK' rate='7.4905'/>
            <Cube currency='RUB' rate='43.2260'/>
            <Cube currency='TRY' rate='2.5515'/>
            <Cube currency='AUD' rate='1.4296'/>
            <Cube currency='BRL' rate='2.9737'/>
            <Cube currency='CAD' rate='1.3705'/>
            <Cube currency='CNY' rate='8.0832'/>
            <Cube currency='HKD' rate='10.2239'/>
            <Cube currency='IDR' rate='13088.24'/>
            <Cube currency='ILS' rate='4.7891'/>
            <Cube currency='INR' rate='78.1200'/>
            <Cube currency='KRW' rate='1521.52'/>
            <Cube currency='MXN' rate='17.5558'/>
            <Cube currency='MYR' rate='4.2222'/>
            <Cube currency='NZD' rate='1.7004'/>
            <Cube currency='PHP' rate='57.707'/>
            <Cube currency='SGD' rate='1.6790'/>
            <Cube currency='THB' rate='41.003'/>
            <Cube currency='ZAR' rate='13.4906'/>
        </Cube>
    </Cube>
</gesmes:Envelope>

我想要的是搜索特定货币（来自用户输入）并取回汇率，以便我可以使用结果。

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2 回答 2

10

您有一个命名空间的 XML 文件。ElementTree 对命名空间不太聪明。你需要给.find(),findall()和iterfind()方法一个明确的命名空间字典。这没有很好地记录：

namespaces = {'ex': 'http://www.ecb.int/vocabulary/2002-08-01/eurofxref'} # add more as needed

for cube in root.findall('.//ex:Cube[@currency]', namespaces=namespaces):
    print(cube.attrib['currency'], cube.attrib['rate'])

这使用了一个简单的 XPath 查询；'.//' 表示查找任何子标签，ex:Cube将搜索限制<Cube>在命名空间中标有ex前缀（来自namespaces映射）的标签，并将[@currency]搜索限制在具有currency属性的元素。

演示：

>>> import requests
>>> r = requests.get('http://www.ecb.int/stats/eurofxref/eurofxref-daily.xml', stream=True)
>>> from xml.etree import ElementTree as ET
>>> tree = ET.parse(r.raw)
>>> root = tree.getroot()
>>> namespaces = {'ex': 'http://www.ecb.int/vocabulary/2002-08-01/eurofxref'}
>>> for cube in root.findall('.//ex:Cube[@currency]', namespaces=namespaces):
...     print(cube.attrib['currency'], cube.attrib['rate'])
... 
USD 1.3180
JPY 128.66
BGN 1.9558
CZK 25.825
DKK 7.4582
GBP 0.85330
HUF 298.87
LTL 3.4528
LVL 0.7016
PLN 4.3289
RON 4.5350
SEK 8.6927
CHF 1.2257
NOK 7.9090
HRK 7.4905
RUB 43.2260
TRY 2.5515
AUD 1.4296
BRL 2.9737
CAD 1.3705
CNY 8.0832
HKD 10.2239
IDR 13088.24
ILS 4.7891
INR 78.1200
KRW 1521.52
MXN 17.5558
MYR 4.2222
NZD 1.7004
PHP 57.707
SGD 1.6790
THB 41.003
ZAR 13.4906

您也可以使用此信息来搜索具体费率；要么构建一个字典，要么直接在 XML 文档中搜索匹配的货币：

currency = input('What currency are you looking for? ')
match = root.find('.//ex:Cube[@currency="{}"]'.format(currency.upper()), namespaces=namespaces)
if match is not None:
    print('The rate for {} is {}'.format(currency, match.attrib['rate']))
于 2013-06-22T12:27:31.590 回答
1

你也可以这样做：

from xml.etree import cElementTree as ET
full_file = 'eurofxref-daily.xml'    # has to be full path
tree = ET.ElementTree(file=full_file)
root = tree.getroot()

for child in root:
    for subchild in child:
        for subsubchild in subchild:
            print(subsubchild.attrib['currency'])
            print(subsubchild.attrib['rate'])
于 2018-04-22T09:56:49.157 回答