Hi Adam
[You seem to have sent the same message twice to the mailing list.]
There are various strategies/approaches to creating the data frame
from the XML.
Perhaps the approach that most closely follows your approach is
xmlRoot(doc)[ "row" ]
which returns a list of XML nodes whose node name is "row" that are
children of the root node <data>.
So
sapply(xmlRoot(doc) [ "row" ], xmlAttrs)
yields a matrix with as many columns as there are <row> nodes
and with 3 rows - one for each of the BRAND, YEAR and VALUE attributes.
So
d = t( sapply(xmlRoot(doc) [ "row" ], xmlAttrs) )
gives you a matrix with the correct rows and column orientation
and now you can turn that into a data frame, converting the
columns into numbers, etc. as you want with regular R commands
(i.e. independently of the XML).
D.
On 1/22/13 1:43 PM, Adam Gabbert wrote:
> Hello,
>
> I'm attempting to read information from an XML into a data frame in R using
> the "XML" package. I am unable to get the data into a data frame as I would
> like. I have some sample code below.
>
> *XML Code:*
>
> Header...
>
> Data I want in a data frame:
>
> <data>
> <row BRAND="GMC" NUM="1" YEAR="1999" VALUE="10000" />
> <row BRAND="FORD" NUM="1" YEAR="2000" VALUE="12000" />
> <row BRAND="GMC" NUM="1" YEAR="2001" VALUE="12500" />
> <row BRAND="FORD" NUM="1" YEAR="2002" VALUE="13000" />
> <row BRAND="GMC" NUM="1" YEAR="2003" VALUE="14000" />
> <row BRAND="FORD" NUM="1" YEAR="2004" VALUE="17000" />
> <row BRAND="GMC" NUM="1" YEAR="2005" VALUE="15000" />
> <row BRAND="GMC" NUM="1" YEAR="1967" VALUE="PRICLESS" />
> <row BRAND="FORD" NUM="1" YEAR="2007" VALUE="17500" />
> <row BRAND="GMC" NUM="1" YEAR="2008" VALUE="22000" />
> </data>
>
> *R Code:*
>
> doc< -xmlInternalTreeParse ("Sample2.xml")
> top <- xmlRoot (doc)
> xmlName (top)
> names (top)
> art <- top [["row"]]
> art
> **
> *Output:*
>
>> art<row BRAND="GMC" NUM="1" YEAR="1999" VALUE="10000"/>
>
> * *
>
>
> This is where I am having difficulties. I am unable to "access" additional
> rows; ( i.e. <row BRAND="GMC" NUM="1" YEAR="1967" VALUE="PRICLESS" /> )
>
> and I am unable to access the individual entries to actually create the
> data frame. The data frame I would like is as follows:
>
> BRAND NUM YEAR VALUE
> GMC 1 1999 10000
> FORD 2 2000 12000
> GMC 1 2001 12500
> etc........
>
> Any help or suggestions would be appreciated. Conversly, my eventual goal
> would be to take a data frame and write it into an XML in the previously
> shown format.
>
> Thank you
>
> AG
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> 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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