R devel - May 2007 - XML parsing under R / Extracting nodes’ values

Hi,
I have an XML file which contains among other nodes :

===myXMLfile.xml==(?)
<nbRelations>2</nbRelations>
<nbActors>2</nbActors>
(...)
<nbRuns>5</nbRuns>
<nbStep>2000</nbStep>
(?)
===End file==I need to extract those values and to make them R variables such
as:
nbRelations = 2
nbActors = 2

nbRuns = 5
nbSteps = 2000

I read the help and have seen the examples of the xml package, it
seems that I need to use xmlTreeParse() function but I don't know how
exactly as I'm not an R advanced programmer, please can anyone show me
how to do that explicitly ?

Any help would be much appreciated

Thanks,

Abdel
University of Boumerd?s
Algeria

- you should have posted to either R-help or (more appropriately) to
the omega-help list.

That said, you need something like this:

root.node <- xmlTreeParse(x, useInternalNodes = TRUE)
nbrelation.set <- getNodeSet(root.node, "//nbRelations")
nbrelation.list <- sapply(nbrelation.set, function(x) { xmlValue(x) } )

and nbrelation.list now contains the "2" in
nbRelations as text - you may want to do as.numeric() on it as well.

Abdelhakim z wrote:
> Hi,
> I have an XML file which contains among other nodes :
> 
> ===myXMLfile.xml==> (?)
> <nbRelations>2</nbRelations>
> <nbActors>2</nbActors>
> (...)
> <nbRuns>5</nbRuns>
> <nbStep>2000</nbStep>
> (?)
> ===End file==> I need to extract those values and to make them R
variables such as:
> nbRelations = 2
> nbActors = 2
> 
> nbRuns = 5
> nbSteps = 2000
> 
> I read the help and have seen the examples of the xml package, it
> seems that I need to use xmlTreeParse() function but I don't know how
> exactly as I'm not an R advanced programmer, please can anyone show me
> how to do that explicitly ?
> 
> Any help would be much appreciated
> 
> Thanks,
> 
> Abdel
> University of Boumerd?s
> Algeria
> 
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