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<p class="c1"><span class="c2">Dokument 1 von 3</span></p>
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<br><p class="c1"><span class="c2">Associated Press Financial Wire</span></p>
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<p class="c1"><span class="c2">April 25, 2012 Wednesday 9:18 PM GMT </span></p>
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<p class="c5"><span class="c6">Apple CEO Tim Cook emerges from Steve Jobs' shadow</span></p>
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<p class="c5"><span class="c7">BYLINE: </span><span class="c2">By PETER SVENSSON, AP Technology Writer</span></p>
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<p class="c5"><span class="c7">SECTION: </span><span class="c2">BUSINESS NEWS</span></p>
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<p class="c5"><span class="c7">LENGTH: </span><span class="c2">794 words</span></p>
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<p class="c5"><span class="c7">DATELINE: </span><span class="c2">NEW YORK </span></p>
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<p class="c8"><span class="c2"> MAIN TEXT 1</span></p>
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<p class="c5"><span class="c7">LOAD-DATE: </span><span class="c2">April 26, 2012</span></p>
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<p class="c5"><span class="c7">LANGUAGE: </span><span class="c2">ENGLISH</span></p>
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<p class="c5"><span class="c7">PUBLICATION-TYPE: </span><span class="c2">Newswire</span></p>
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<br><p class="c1"><span class="c2">Copyright 2012 Associated Press<br>All Rights Reserved</span></p>
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我是xpath的新手,我想將它與R(Duncan Lang的xml包)結合使用來查詢我從LexisNexis收到的html文檔。該文檔包含多個新聞文章,每篇文章都以<DOC NUMBER=1> <DOCFULL>
標籤爲邊界。我希望爲每個文檔提取一些信息,例如提取部分的信息,我能走到今天:xpath表達式不起作用
doc <- htmlParse("hmtldoc.HTML")
xpathSApply(doc,"//span[text()='SECTION: ']/..", xmlValue)
這給了我:
[1] "SECTION: BUSINESS NEWS" "SECTION: BUSINESS NEWS" "SECTION: BUSINESS NEWS"
即輸出我可以工作。主要問題是不是每篇文章都有SECTION信息。我需要知道的是哪篇文章提供了這些信息,哪些不能,最好是通過返回NA或空列表元素,這樣我就可以自己推斷出這些信息。
與此相關的問題:我試着拿出我第一次選擇的無論是DOC或DOCFULL節點,並從那裏去了一個解決方案,例如:
xpathSApply(doc,"//DOCFULL/*/span[text()='SECTION: ']/..", xmlValue)
我想這應該返回相同的文字如上所述,但事實並非如此。無論如何,我對這種語言仍然很陌生,並感謝任何幫助。
有兩個問題與此問題:1. XML文檔格式不正確嚴重 - 每一個兼容的XML解析器會引發錯誤在上面。 2.你不指定你想要選擇的節點。 –