我有一個結構如下所示的 XML 文件（為了這個問題的目的而簡化）。對于每條記錄，我想提取文章標題和“ArticleId”元素中包含DOI編號的屬性“IdType”的值（有時這個屬性可能會丟失），然后將文章標題存儲在帶有DOI的字典中作為關鍵。<PubmedArticleSet><PubmedArticle>    <MedlineCitation Status="MEDLINE" Owner="NLM">        <Article PubModel="Print-Electronic">            <ArticleTitle>Malathion and dithane induce DNA damage in Vicia faba.</ArticleTitle>        </Article>    </MedlineCitation>      <PubmedData>        <ArticleIdList>            <ArticleId IdType="pubmed">28950791</ArticleId>            <ArticleId IdType="doi">10.1177/0748233717726877</ArticleId>        </ArticleIdList>    </PubmedData></PubmedArticle>為了實現這一點，我使用了 xml.etree.ElementTree，如下所示：import xml.etree.ElementTree as ETxmldoc = ET.parse('sample.xml')root = xmldoc.getroot()pubs = {}for elem in xmldoc.iter(tag='ArticleTitle'):    title = elem.text    for subelem in xmldoc.iter(tag='ArticleId'):        if subelem.get("IdType") == "doi":            doi = subelem.text             pubs[doi] = titleif len(pubs) == 0:   print "No articles found"else:      for pub in pubs.keys():       print pub + ' ' + pubs[pub]但是遍歷文檔樹的循環有問題，因為上面的代碼導致：10.1177/0748233717726877 [Influence of Four Kinds of PPCPs on Micronucleus Rate of the Root-Tip Cells of Vicia-faba and Garlic].10.1016/j.crvi.2015.02.001 [Influence of Four Kinds of PPCPs on Micronucleus Rate of the Root-Tip Cells of Vicia-faba and Garlic].也就是說，我得到了正確的 DOI，但只是上一篇文章標題的副本，沒有 DOI！正確的輸出應該是：10.1177/0748233717726877 Malathion and dithane induce DNA damage in Vicia faba.10.1016/j.crvi.2015.02.001 Impact of dual inoculation with Rhizobium and PGPR on growth and antioxidant status of Vicia faba L. under copper stress.任何人都可以向我提供一些解決這個煩人問題的提示嗎？