如何用xml.etree.elementtree解析XML？

Question

我正在尝试使用XML.Etree.Elementree来解析XML，但我无法提取信息“ articletitle” and code>“ descriptorneName” “ descriptorname” >分别将变量分为字符串列表。 我调试代码，root总是空的。似乎代码找到标签，但我尝试获取的内容却没有。

此外，下面的代码表明我只是想获取标签“ descriptorname”的文本，但是在第二步中，我还需要“ ui”（例如：： “ D000368”）的某个descriptorname标签。我也很感谢如何访问这些价值观的任何提示。

import xml.etree.ElementTree as ET

# efetch function is from a module which queries pubmed API. Content of response of the API is a XML you can find below in the second code snippet.
response = efetch(['35590280', '35590281'])

root = ET.fromstring(response.content)

for article in root.findall('PubmedArticle'):
    article_title = article.find('ArticleTitle')
    meshcodes = article.findall('DescriptorName')
    print(article_title, meshcodes)

输出控制台：

None []
None []

根据我的理解，root应该是＆lt; pubMedArticlesetet \＆gt;，孩子应为＆lt; pubmedarmarticle \＆gt;。一个＆lt; pubMedarticlesetEt \＆gt;可以由数百个＆lt; pubMedialticle \＆gt; s组成。

<?xml version="1.0" ?>
<!DOCTYPE PubmedArticleSet PUBLIC "-//NLM//DTD PubMedArticle, 1st January 2019//EN" "https://dtd.nlm.nih.gov/ncbi/pubmed/out/pubmed_190101.dtd">
<PubmedArticleSet>
    <PubmedArticle>
        <MedlineCitation Status="MEDLINE" IndexingMethod="Automated" Owner="NLM">
            <PMID Version="1">35590280</PMID>
            <DateCompleted>
                <Year>2022</Year>
                <Month>05</Month>
                <Day>23</Day>
            </DateCompleted>
            <DateRevised>
                <Year>2022</Year>
                <Month>05</Month>
                <Day>23</Day>
            </DateRevised>
            <Article PubModel="Electronic">
                <Journal>
                    <ISSN IssnType="Electronic">1471-2474</ISSN>
                    <JournalIssue CitedMedium="Internet">
                        <Volume>23</Volume>
                        <Issue>1</Issue>
                        <PubDate>
                            <Year>2022</Year>
                            <Month>May</Month>
                            <Day>19</Day>
                        </PubDate>
                    </JournalIssue>
                    <Title>BMC musculoskeletal disorders</Title>
                    <ISOAbbreviation>BMC Musculoskelet Disord</ISOAbbreviation>
                </Journal>
                <ArticleTitle>Risk factors of fracture following curettage for bone giant cell tumors of the extremities.</ArticleTitle>
                <Pagination>
                    <MedlinePgn>477</MedlinePgn>
                </Pagination>
                <ELocationID EIdType="doi" ValidYN="Y">10.1186/s12891-022-05447-x</ELocationID>
                <Abstract>
                    <AbstractText Label="BACKGROUND" NlmCategory="BACKGROUND">Following curettage of giant cell tumor of bone (GCTB), it is common to fill the cavity with polymethylmethacrylate (PMMA) bone cement, bone allograft, or artificial bone to maintain bone strength; however, there is a 2-14% risk of postoperative fractures. We conducted this retrospective study to clarify the risk factors for fractures after curettage for GCTB of the extremities.</AbstractText>
                    <AbstractText Label="METHODS" NlmCategory="METHODS">This study included 284 patients with GCTBs of the extremities who underwent curettage at our institutions between 1980 and 2018 after excluding patients whose cavities were not filled with anything or who had additional plate fixation. The tumor cavity was filled with PMMA bone cement alone (n = 124), PMMA bone cement and bone allograft (n = 81), bone allograft alone (n = 63), or hydroxyapatite graft alone (n = 16).</AbstractText>
                    <AbstractText Label="RESULTS" NlmCategory="RESULTS">Fractures after curettage occurred in 10 (3.5%) patients, and the median time from the curettage to fracture was 3.5 months (interquartile range [IQR], 1.8-8.3 months). The median postoperative follow-up period was 86.5 months (IQR, 50.3-118.8 months). On univariate analysis, patients who had GCTB of the proximal or distal femur (1-year fracture-free survival, 92.5%; 95% confidence interval [CI]: 85.8-96.2) presented a higher risk for postoperative fracture than those who had GCTB at another site (100%; p = 0.0005). Patients with a pathological fracture at presentation (1-year fracture-free survival, 88.2%; 95% CI: 63.2-97.0) presented a higher risk for postoperative fracture than those without a pathological fracture at presentation (97.8%; 95% CI: 95.1-99.0; p = 0.048). Patients who received bone grafting (1-year fracture-free survival, 99.4%; 95% CI: 95.7-99.9) had a lower risk of postoperative fracture than those who did not receive bone grafting (94.4%; 95% CI: 88.7-97.3; p = 0.003).</AbstractText>
                    <AbstractText Label="CONCLUSIONS" NlmCategory="CONCLUSIONS">For GCTBs of the femur, especially those with pathological fracture at presentation, bone grafting after curettage is recommended to reduce the risk of postoperative fracture. Additional plate fixation should be considered when curettage and cement filling without bone grafting are performed in patients with GCTB of the femur. This should be specially performed for those patients with a pathological fracture at presentation.</AbstractText>
                    <CopyrightInformation>© 2022. The Author(s).</CopyrightInformation>
                </Abstract>
                <AuthorList CompleteYN="Y">
                    <Author ValidYN="Y">
                        <LastName>Tsukamoto</LastName>
                        <ForeName>Shinji</ForeName>
                        <Initials>S</Initials>
                        <AffiliationInfo>
                            <Affiliation>Department of Orthopaedic Surgery, Nara Medical University, 840g, Shijo-cho, Kashihara-city, Nara, 634-8521, Japan. [email protected].</Affiliation>
                        </AffiliationInfo>
                    </Author>
                    <Author ValidYN="Y">
                        <LastName>Mavrogenis</LastName>
                        <ForeName>Andreas F</ForeName>
                        <Initials>AF</Initials>
                        <AffiliationInfo>
                            <Affiliation>First Department of Orthopaedics, National and Kapodistrian University of Athens, School of Medicine, 41 Ventouri Street, 15562 Holargos, Athens, Greece.</Affiliation>
                        </AffiliationInfo>
                    </Author>
                    <Author ValidYN="Y">
                        <LastName>Akahane</LastName>
                        <ForeName>Manabu</ForeName>
                        <Initials>M</Initials>
                        <AffiliationInfo>
                            <Affiliation>Department of Health and Welfare Services, National Institute of Public Health, 2-3-6 Minami, Wako-shi, Saitama, 351-0197, Japan.</Affiliation>
                        </AffiliationInfo>
                    </Author>
                    <Author ValidYN="Y">
                        <LastName>Honoki</LastName>
                        <ForeName>Kanya</ForeName>
                        <Initials>K</Initials>
                        <AffiliationInfo>
                            <Affiliation>Department of Orthopaedic Surgery, Nara Medical University, 840g, Shijo-cho, Kashihara-city, Nara, 634-8521, Japan.</Affiliation>
                        </AffiliationInfo>
                    </Author>
                    <Author ValidYN="Y">
                        <LastName>Kido</LastName>
                        <ForeName>Akira</ForeName>
                        <Initials>A</Initials>
                        <AffiliationInfo>
                            <Affiliation>Department of Rehabilitation Medicine, Nara Medical University, 840, Shijo-cho, Kashihara-city, Nara, 634-8521, Japan.</Affiliation>
                        </AffiliationInfo>
                    </Author>
                    <Author ValidYN="Y">
                        <LastName>Tanaka</LastName>
                        <ForeName>Yasuhito</ForeName>
                        <Initials>Y</Initials>
                        <AffiliationInfo>
                            <Affiliation>Department of Orthopaedic Surgery, Nara Medical University, 840g, Shijo-cho, Kashihara-city, Nara, 634-8521, Japan.</Affiliation>
                        </AffiliationInfo>
                    </Author>
                    <Author ValidYN="Y">
                        <LastName>Donati</LastName>
                        <ForeName>Davide Maria</ForeName>
                        <Initials>DM</Initials>
                        <AffiliationInfo>
                            <Affiliation>Department of Orthopaedic Oncology, IRCCS Istituto Ortopedico Rizzoli, Via Pupilli 1, 40136, Bologna, Italy.</Affiliation>
                        </AffiliationInfo>
                    </Author>
                    <Author ValidYN="Y">
                        <LastName>Errani</LastName>
                        <ForeName>Costantino</ForeName>
                        <Initials>C</Initials>
                        <AffiliationInfo>
                            <Affiliation>Department of Orthopaedic Oncology, IRCCS Istituto Ortopedico Rizzoli, Via Pupilli 1, 40136, Bologna, Italy.</Affiliation>
                        </AffiliationInfo>
                    </Author>
                </AuthorList>
                <Language>eng</Language>
                <PublicationTypeList>
                    <PublicationType UI="D016428">Journal Article</PublicationType>
                </PublicationTypeList>
                <ArticleDate DateType="Electronic">
                    <Year>2022</Year>
                    <Month>05</Month>
                    <Day>19</Day>
                </ArticleDate>
            </Article>
            <MedlineJournalInfo>
                <Country>England</Country>
                <MedlineTA>BMC Musculoskelet Disord</MedlineTA>
                <NlmUniqueID>100968565</NlmUniqueID>
                <ISSNLinking>1471-2474</ISSNLinking>
            </MedlineJournalInfo>
            <ChemicalList>
                <Chemical>
                    <RegistryNumber>0</RegistryNumber>
                    <NameOfSubstance UI="D001843">Bone Cements</NameOfSubstance>
                </Chemical>
                <Chemical>
                    <RegistryNumber>9011-14-7</RegistryNumber>
                    <NameOfSubstance UI="D019904">Polymethyl Methacrylate</NameOfSubstance>
                </Chemical>
            </ChemicalList>
            <CitationSubset>IM</CitationSubset>
            <MeshHeadingList>
                <MeshHeading>
                    <DescriptorName UI="D001843" MajorTopicYN="N">Bone Cements</DescriptorName>
                    <QualifierName UI="Q000009" MajorTopicYN="N">adverse effects</QualifierName>
                </MeshHeading>
                <MeshHeading>
                    <DescriptorName UI="D001859" MajorTopicYN="Y">Bone Neoplasms</DescriptorName>
                    <QualifierName UI="Q000473" MajorTopicYN="N">pathology</QualifierName>
                    <QualifierName UI="Q000601" MajorTopicYN="N">surgery</QualifierName>
                </MeshHeading>
                <MeshHeading>
                    <DescriptorName UI="D003475" MajorTopicYN="N">Curettage</DescriptorName>
                    <QualifierName UI="Q000009" MajorTopicYN="N">adverse effects</QualifierName>
                </MeshHeading>
                <MeshHeading>
                    <DescriptorName UI="D005121" MajorTopicYN="N">Extremities</DescriptorName>
                    <QualifierName UI="Q000473" MajorTopicYN="N">pathology</QualifierName>
                </MeshHeading>
                <MeshHeading>
                    <DescriptorName UI="D005598" MajorTopicYN="Y">Fractures, Spontaneous</DescriptorName>
                    <QualifierName UI="Q000000981" MajorTopicYN="N">diagnostic imaging</QualifierName>
                    <QualifierName UI="Q000453" MajorTopicYN="N">epidemiology</QualifierName>
                    <QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName>
                </MeshHeading>
                <MeshHeading>
                    <DescriptorName UI="D018212" MajorTopicYN="Y">Giant Cell Tumor of Bone</DescriptorName>
                    <QualifierName UI="Q000473" MajorTopicYN="N">pathology</QualifierName>
                    <QualifierName UI="Q000601" MajorTopicYN="N">surgery</QualifierName>
                </MeshHeading>
                <MeshHeading>
                    <DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName>
                </MeshHeading>
                <MeshHeading>
                    <DescriptorName UI="D009364" MajorTopicYN="N">Neoplasm Recurrence, Local</DescriptorName>
                    <QualifierName UI="Q000601" MajorTopicYN="N">surgery</QualifierName>
                </MeshHeading>
                <MeshHeading>
                    <DescriptorName UI="D019904" MajorTopicYN="N">Polymethyl Methacrylate</DescriptorName>
                </MeshHeading>
                <MeshHeading>
                    <DescriptorName UI="D012189" MajorTopicYN="N">Retrospective Studies</DescriptorName>
                </MeshHeading>
                <MeshHeading>
                    <DescriptorName UI="D012307" MajorTopicYN="N">Risk Factors</DescriptorName>
                </MeshHeading>
            </MeshHeadingList>
            <KeywordList Owner="NOTNLM">
                <Keyword MajorTopicYN="N">Bone grafting</Keyword>
                <Keyword MajorTopicYN="N">Cement</Keyword>
                <Keyword MajorTopicYN="N">Curettage</Keyword>
                <Keyword MajorTopicYN="N">Denosumab</Keyword>
                <Keyword MajorTopicYN="N">Fracture</Keyword>
                <Keyword MajorTopicYN="N">Giant cell tumor of bone</Keyword>
            </KeywordList>
        </MedlineCitation>
        <PubmedData>
            <History>
                <PubMedPubDate PubStatus="received">
                    <Year>2021</Year>
                    <Month>10</Month>
                    <Day>18</Day>
                </PubMedPubDate>
                <PubMedPubDate PubStatus="accepted">
                    <Year>2022</Year>
                    <Month>05</Month>
                    <Day>17</Day>
                </PubMedPubDate>
                <PubMedPubDate PubStatus="entrez">
                    <Year>2022</Year>
                    <Month>5</Month>
                    <Day>19</Day>
                    <Hour>23</Hour>
                    <Minute>45</Minute>
                </PubMedPubDate>
                <PubMedPubDate PubStatus="pubmed">
                    <Year>2022</Year>
                    <Month>5</Month>
                    <Day>20</Day>
                    <Hour>6</Hour>
                    <Minute>0</Minute>
                </PubMedPubDate>
                <PubMedPubDate PubStatus="medline">
                    <Year>2022</Year>
                    <Month>5</Month>
                    <Day>24</Day>
                    <Hour>6</Hour>
                    <Minute>0</Minute>
                </PubMedPubDate>
            </History>
            <PublicationStatus>epublish</PublicationStatus>
            <ArticleIdList>
                <ArticleId IdType="pubmed">35590280</ArticleId>
                <ArticleId IdType="doi">10.1186/s12891-022-05447-x</ArticleId>
                <ArticleId IdType="pii">10.1186/s12891-022-05447-x</ArticleId>
                <ArticleId IdType="pmc">PMC9118605</ArticleId>
            </ArticleIdList>
            <ReferenceList>
                <Reference>
                    <Citation>Clin Orthop Relat Res. 2020 May;478(5):1076-1085</Citation>
                    <ArticleIdList>
                        <ArticleId IdType="pubmed">31794487</ArticleId>
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                <Reference>
                    <Citation>J Bone Joint Surg Am. 2018 Mar 21;100(6):496-504</Citation>
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                <Reference>
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    <PubmedArticle>
    ...
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</PubmedArticleSet>

Answer 1

循环访问所有我需要的所有信息的最终解决方案如下：

for article in root.findall('PubmedArticle'):
    article_title = article.find("MedlineCitation//ArticleTitle").text
    meshcodes = [code.text for code in article.findall('MedlineCitation//DescriptorName')]
    meshcodes_ui = [code.attrib['UI'] for code in article.findall(
        'MedlineCitation//DescriptorName')]
    print(article_title, meshcodes, meshcodes_ui)

@larsks和@alberto Hanna的Kudos

Answer 2

PubMedIrticle元素不包含articletitle元素。 articletitle元素在PubMedIcticle/Medlinecitation/Article中。因此，您可以写：

for article in root.findall("PubmedArticle"):
    article_title = article.find("MedlineCitation").find("Article").find("ArticleTitle")
    print(article_title.text)

或者您可以使用XPath表达式：

for article in root.findall("PubmedArticle"):
    article_title = article.find("MedlineCitation//ArticleTitle")
    print(article_title.text)

Answer 3

我想您正在寻找这样的东西

import xml.etree.ElementTree as ET

tree = ET.parse('xx.xml')
root = tree.getroot()

for article in root.findall(".//PubmedArticle"):
    article_title = article.find(".//ArticleTitle")
    print(article_title.text)

for descriptor_name in root.findall('.//DescriptorName'):
    if descriptor_name.text == 'Bone Cements':
        print(descriptor_name.get('UI'))