How to create an R data frame from an xml file?

Question

I have an XML Document file. The part of the file looks like this:

-<attr>  
     <attrlabl>COUNTY</attrlabl>  
     <attrdef>County abbreviation</attrdef>  
     <attrtype>Text</attrtype>  
     <attwidth>1</attwidth>  
     <atnumdec>0</atnumdec>  
    -<attrdomv>  
        -<edom>  
            <edomv>C</edomv>  
            <edomvd>Clackamas County</edomvd>  
            <edomvds/>  
         </edom>  
        -<edom>  
            <edomv>M</edomv>  
            <edomvd>Multnomah County</edomvd>  
            <edomvds/>  
         </edom>  
        -<edom>  
            <edomv>W</edomv>  
            <edomvd>Washington County</edomvd>  
            <edomvds/>  
         </edom>  
     </attrdomv>  
 </attr>

From this XML file, I want to create an R data frame with the columns of attrlabl, attrdef, attrtype, and attrdomv. Please note that the attrdomv column should include all of the levels for the category variable. The data frame should look like this:

attrlabl    attrdef                attrtype    attrdomv  
COUNTY      County abbreviation    Text        C Clackamas County; M Multnomah County; W Washington County

I have an incomplete code like this:

doc <- xmlParse("taxlots.shp.xml")  
dataDictionary <- xmlToDataFrame(getNodeSet(doc,"//attrlabl"))

Could you please complete my R code? I appreciate any help!

@agstudy: could you please tell me how to send my xml file to you? — POTENZA, Nov 27 '12 at 09:02
you can't here, but you can use a file upload service like SkyDrive and post the link file — agstudy, Nov 27 '12 at 09:10

plannapus · Accepted Answer · 2012-11-27T09:26:02.830

Assuming this is the correct taxlots.shp.xml file:

<attr>  
     <attrlabl>COUNTY</attrlabl>  
     <attrdef>County abbreviation</attrdef>  
     <attrtype>Text</attrtype>  
     <attwidth>1</attwidth>  
     <atnumdec>0</atnumdec>  
    <attrdomv>  
        <edom>  
            <edomv>C</edomv>  
            <edomvd>Clackamas County</edomvd>  
            <edomvds/>  
         </edom>  
        <edom>  
            <edomv>M</edomv>  
            <edomvd>Multnomah County</edomvd>  
            <edomvds/>  
         </edom>  
        <edom>  
            <edomv>W</edomv>  
            <edomvd>Washington County</edomvd>  
            <edomvds/>  
         </edom>  
     </attrdomv>  
 </attr>

You were almost there:

doc <- xmlParse("taxlots.shp.xml")
xmlToDataFrame(nodes=getNodeSet(doc1,"//attr"))[c("attrlabl","attrdef","attrtype","attrdomv")]
  attrlabl             attrdef attrtype                                             attrdomv
1   COUNTY County abbreviation     Text CClackamas CountyMMultnomah CountyWWashington County

But the last field has not the format you wanted. To do so, require some additional steps:

step1 <- xmlToDataFrame(nodes=getNodeSet(doc1,"//attrdomv/edom"))
step1
  edomv            edomvd edomvds
1     C  Clackamas County        
2     M  Multnomah County        
3     W Washington County  

step2 <- paste(paste(step1$edomv, step1$edomvd, sep=" "), collapse="; ")
step2
[1] "C Clackamas County; M Multnomah County; W Washington County"

cbind(xmlToDataFrame(nodes= getNodeSet(doc1, "//attr"))[c("attrlabl", "attrdef", "attrtype")],
      attrdomv= step2)
  attrlabl             attrdef attrtype                                                      attrdomv
1   COUNTY County abbreviation     Text C Clackamas County; M Multnomah County; W Washington County

How to create an R data frame from an xml file?

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