[R] XML - get node by name

Gabor Grothendieck ggrothendieck at gmail.com
Sun Sep 7 21:38:04 CEST 2008


On Sun, Sep 7, 2008 at 2:56 PM, Antje <niederlein-rstat at yahoo.de> wrote:
> Thanks a lot to Gabor and Duncan!
>
> I didn't know that XPath is a standard. I'll give it a deeper look to better
> understand it.
>
> Oh, I guess I understand a bit more
>
> xpathApply(doc, "//val", function(n) xmlValue(n))

or just

xpathApply(doc, "//val", xmlValue)


>
> would search globally for all nodes named "val" and return its values :-)
> So that's excactly what I was looking for. Not caring about the exact
> location of a node.
> I think, in my case it should be okay, to parse for nodes just by their
> names.
>
> Thanks again!
>
> @ Ajay: Sorry, but I was looking for a solution with R
> @ Dirk: I already used the XML package but didn't know the possibilities to
> access data as I was used to.
>
>
>
> Antje schrieb:
>>
>> Hi there,
>>
>> I try to rewrite some Java-code with R. It deals with reading XML files. I
>> started with the XML package. In Java, I had a very useful method which gave
>> me a node by using:
>>
>> name of the node
>> index of appearance
>> start point: global (false) / local (true)
>>
>> So, I could do something like this.
>>
>> setCurrentChildNode("data", 0);
>> getValueOfElement("val",1,true);
>> --> gives 45
>>
>> setCurrentChildNode("data", 1);
>> getValueOfElement("val",1,true);
>> --> gives 11
>>
>> getValueOfElement("val",1,false);
>> --> gives 45
>>
>> <root>
>>  <data loc="1">
>>    <val i="t1"> 22 </val>
>>    <val i="t2"> 45 </val>
>>  </data>
>>  <data loc="2">
>>    <val i="t1"> 44 </val>
>>    <val i="t2"> 11 </val>
>>  </data>
>> </root>
>>
>> Now, I'd like to do something like this in R. Most important would be to
>> retrieve a node just by its name, not by the whole path. How is it possible?
>>
>> Can anybody help me with this issue?
>>
>> Antje
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



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