Removing parent nodes from xml file in r - r

Question

I have xml output below. I am trying to remove parents using XML or xml2 library from R. I found a similar post here but those functions somehow gave me an error. I am trying to remove those parents until analysisdata parent. That is what I am going to parse.
<assessment>
<itembank />
<instrument id="797393 ">
<form id="Math G3">
<formitem id="8243" position="0" />
</form>
</instrument>
<admin id="797393 " instrument="797393 ">
<genatt name="adminperiod" value="SP19" />
<responseanalyses>
<responsebankref id="3M" />
<analysisdefs>
<analysisoption name="mark" value="no" />
<analysisoption name="notreached" value="ASNOTPRESENTED" />
<statentity type="item" id="8243" varname="I_8243">
<genatt name="type" value="CR" />
<genatt name="codestart" value="0" />
<genatt name="validcodes" value="2" />
<genatt name="omitcode" value="9" />
<genatt name="notpresentedcode" value="8" />
<statentity code="0.000000" id="0.000000" type="itemscorept" />
<statentity code="1.000000" id="1.000000" type="itemscorept" />
<statentity code="9" id="omit" type="itemscorept" />
</statentity>
<genatt name="type" value="CR" />
<genatt name="codestart" value="0" />
<genatt name="validcodes" value="2" />
<genatt name="omitcode" value="9" />
<genatt name="notpresentedcode" value="8" />
<statentity code="0.000000" id="0.000000" type="itemscorept" />
<statentity code="1.000000" id="1.000000" type="itemscorept" />
<statentity code="9" id="omit" type="itemscorept" />
</statentity>
<statentity id="DIFGROUP_TTS" varname="DIFGROUP_TTS" type="popgroup" description="DIFGROUP_TTS">
<statentity code="0.000000" id="0.000000" description="0.000000" samplesize="40501" type="popsubgroup" />
<statentity code="1.000000" id="1.000000" description="1.000000" samplesize="5532" type="popsubgroup" />
</statentity>
</analysisdefs>
<genatt name="xmloutputfile" value="J:\out.xml" />
<analysis creator="ST" description="" level="form" type="classical">
<analysisdata formid="Math G3">
<statentityref id="8243" type="item">
<statval type="OmitCount" value="0.000000" />
<statval type="NotReachedCount" value="43.000000" />
<statval type="PolyserialCorrelation" value="0.644181" />
<statval type="AdjustedPolyserial" value="0.644181" />
<statval type="AverageScore" value="0.223074" se="0.011957" />
<statval type="NCount" value="2609.000000" />
<statval type="StdevItemScore" value="0.416308" />
</statentityref>
</statentityref>
</statentityref>
</analysisdata>
</analysis>
</responseanalyses>
<responsebank findin="J:\outAM.am" sourcetype="AM" id="3M" />
</admin>
</assessment>
I tried
library(xml2)
library(XML)
newdoc <- xpathApply(doc, "/assessment/admin/responseanalyses") I get this error after running this: Error in UseMethod("xpathApply") :
no applicable method for 'xpathApply' applied to an object of class "c('xml_document', 'xml_node')". THis solution was suggested here.
After removing those parent nodes, I would like to have analysisdata node only after removing the assessment/admin/responseanalyses parent node. Desired out is like this below:
<analysisdata formid="Math G3">
<statentityref id="8243" type="item">
<statval type="OmitCount" value="0.000000" />
<statval type="NotReachedCount" value="43.000000" />
<statval type="PolyserialCorrelation" value="0.644181" />
<statval type="AdjustedPolyserial" value="0.644181" />
<statval type="AverageScore" value="0.223074" se="0.011957" />
<statval type="NCount" value="2609.000000" />
<statval type="StdevItemScore" value="0.416308" />
</statentityref>
</statentityref>
</statentityref>
</analysisdata>
Any thoughts?
Thanks!

Answer 1

You could use html_node from rvest library
rvest::html_node(doc, 'analysisdata')