[R] using XML package to read RSS

[Duncan Temple Lang]

Hi James.

 Yes, you need to identify the namespace in the query, e.g.

  getNodeSet(doc, "//x:entry", c(x = "http://www.w3.org/2005/Atom"))

This yeilds 40 matching nodes.

(getNodeSet() is more convenient to use when you don't specify a function
to apply to the nodes. Also, you don't need xmlRoot(doc), as it works on the
entire document with the query "//...".)

 BTW, you want to use xmlParse() and not xmlTreeParse().

   D.


On 5/16/12 6:40 PM, J Toll wrote:
> Hi,
> 
> I'm trying to use the XML package to read an RSS feed.  To get
> started, I was trying to use this post as an example:
> 
> http://www.r-bloggers.com/how-to-build-a-dataset-in-r-using-an-rss-feed-or-web-page/
> 
> I can replicate the beginning section of the post, but when I try to
> use another RSS feed I have an issue.  The RSS feed I would like to
> use is:
> 
>> URL <- "http://www.sec.gov/cgi-bin/browse-edgar?action=getcurrent&type=&company=&dateb=&owner=include&start=0&count=40&output=atom"
> 
>> library(XML)
>> doc <- xmlTreeParse(URL)
> 
>> src <- xpathApply(xmlRoot(doc), "//entry")
> 
> I get an empty list rather than a list of each of the "entry":
> 
>> src
> list()
> attr(,"class")
> [1] "XMLNodeSet"
> 
> I'm not sure how to fix this.  Any suggestions?  Do I need to provide
> a namespace, or is the RSS malformed?
> 
> Thanks,
> 
> 
> James
> 
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