[plt-scheme] getting data out of xexpr's (xml)

Oh, I see. Yes, match is probably the right thing (using the
quasiquote patterns). There may be a planet library for doing what you
want more directly, I don't know. But assuming not, match.ss.

Robby

On Jan 2, 2008 5:55 PM, Stephen De Gabrielle <stephen at degabrielle.name> wrote:
> Thanks for the quick response;
>
> My trouble isn't geting the xml into xexper, but turning xexpr into
> key/value pairs.
>
> I do this;
>
>                                                       (xml->xexpr
>
> ((eliminate-whitespace '(graphml graph node edge) (lambda (x) x))
>
> (document-element (read-xml input-port))))
>
> Which gets much the same output as this
>
> (require (lib "xml.ss" "xml"))
> (xml->xexpr (read-xml/element (open-input-string "
> <graphml xmlns='http://graphml.graphdrawing.org/xmlns'>
> <!-- metadata -->
> <graph edgedefault='undirected'>
>
> <key id='name' for='node' attr.name='name' attr.type='string'/>
> <key id='gender' for='node' attr.name='gender' attr.type='string'/>
>
> <!-- data -->
> <node id='1'>
>  <data key='name'>Jeff</data>
>  <data key='gender'>M</data>
>  </node>
> <node id='2'>
>  <data key='name'>Ed</data>
>  <data key='gender'>M</data>
> </node>
> <node id='3'>
>  <data key='name'>Christiaan</data>
>  <data key='gender'>M</data>
> </node>
>
> <edge source='2' target='1'></edge>
> <edge source='3' target='3'></edge>
> <edge source='1' target='2'></edge>
>
> </graph>
> </graphml>")))
>
> which gives approximately;
>
> (graphml
>   ((xmlns "http://graphml.graphdrawing.org/xmlns"))
>   (graph
>    ((edgedefault "undirected"))
>    (key ((attr.name "name") (attr.type "string") (for "node") (id "name")))
>    (key ((attr.name "gender") (attr.type "string") (for "node") (id "gender")))
>    (node ((id "1"))  (data ((key "name")) "Jeff")  (data ((key "gender")) "M") )
>    (node ((id "2"))  (data ((key "name")) "Ed")  (data ((key "gender")) "M") )
>    (node ((id "3"))  (data ((key "name")) "Christiaan")  (data ((key
> "gender")) "M") )
>    (edge ((source "21") (target "126")))
>    (edge ((source "21") (target "127")))
>    (edge ((source "21") (target "128")))
>    (edge ((source "21") (target "129")))
>    )
>   )
>
>
> I'd like to use something like a regular expression, perhaps?
>   /(node ((id $1))  (data ((key $2)) $3)/((class node) (id $1) ($2 $3) ($4 $5))/
>
> to get  a series of alists [1];
>
> ((class "graph-metadata") (dir #f))
> ((class "node") (id "1") ("name" "Jeff")  ("gender" "M"))
> ((class "node") (id "2") ("name" "Ed")  ("gender" "M"))
> ((class "node") (id "3") ("name" "Christiaan") ("gender" "M"))
> ((class "edge") (source "21") (target "126") (dir #f))
> ((class "edge") (source "21") (target "127") (dir #f))
> ((class "edge") (source "21") (target "128") (dir #f))
> ((class "edge") (source "21") (target "129") (dir #f))
>
> Does this make more sense? It's turning the xexpr into key/value pairs
> without making a labrinthine mess of for-each/map and caddr etc. like
> in my original code that I need to work out. match.ss seems to be
> about macros, so I'm not sure I'm on the right path.
>
> Thanks,
>
> Stephen
>
>
> [1]Which I will process to add derived fields to ;
> eg  ((class "node") (id "1") ("name" "Jeff")  ("gender" "M")  (x-pos
> 43) (y-pos 34) (colour "Blue"))
> (then finally turn into snips)
>
>
>
>
>
> On Jan 2, 2008 10:54 PM, Robby Findler <robby at cs.uchicago.edu> wrote:
> > I think you want:
> >
> > (require (lib "xml.ss" "xml"))
> > (xml->xexpr (read-xml/element (open-input-string "<a><b>cdef</b></a>")))
> >
> > which produces
> >
> > '(a () (b () "cdef"))
> >
> > hth,
> > Robby
> >
> >
> > On Jan 2, 2008 4:51 PM, Stephen De Gabrielle <stephen at degabrielle.name> wrote:
> > > Hi,
> > >
> > > I'm using  (lib "xml.ss" "xml") to read some GraphML  into xexpr's
> > >
> > >
> > > Once I have loaded it I'm using this sort of (non-working)thing  to
> > > turn it from the xexpr into an alist using for-each and
> > > caddr/cadr/car/cdr etc.
> > >
> > > ;; populate ;;
> > >       (let* ((data (cdr (caddr xexpr-graph)))) ; get the graph part
> > >         (for-each
> > >          (lambda (row) ;; badly named local for node or edge tag.
> > >            (if (equal? '(edgedefault "undirected") row) (set! edge-directed #t)
> > >                (let* ((row-type (car row))
> > >                       (row-Attributes (if (or (equal? row-type 'node)
> > >                                                (equal? row-type
> > > 'edge)) (get-row-Attributes row))))
> > >                  (send alist-collection insert (append (list (list
> > > 'class row-type)) (car row-Attributes) (cadr row-Attributes )))))) ;;
> > > add an alist to the collection for each node or edge
> > >          data))
> > >
> > >  (http://graphml.graphdrawing.org/ socialnet.xml example attached)
> > >
> > > My Question is - is there a better way of getting my nodes, edges and
> > > [graph] metadata(directed/undirected) as what I am writing here is
> > > hard to write, hard to read, and doesn't even work.
> > >
> > > Should I use  plt-match.ss or  match.ss instead?
> > >
> > > Can anyone suggest some code in 'PLT-Full' (v3.99.0.8) that I can
> > > read. It doesn't have to be xml - just xexpr-like - and I am getting
> > > getter at reading code, even without comments :)
> > >
> > >
> > > Cheers,
> > >
> > > Stephen
> > >
> > >
> > >
> > > --
> > > Stephen De Gabrielle
> > > s.degabrielle at ucl.ac.uk
> > > Telephone +44 (0)20 7679 5242 (x45242)
> > > Mobile                  079 851 890 45
> > > http://www.uclic.ucl.ac.uk/annb/MaSI.html
> > > University College London Interaction Centre
> > > Remax House - 31/32 Alfred Place
> > > London - WC1E 7DP
> > >
> > > "There's an old story about the person who wished his computer were as
> > > easy to use as his telephone.  That wish has come true, since I no
> > > longer know how to use my telephone. " -- Bjarne Stroustrup
> > >
> > > _________________________________________________
> > >   For list-related administrative tasks:
> > >   http://list.cs.brown.edu/mailman/listinfo/plt-scheme
> > >
> > >
> >
>
>
>
> --
>
>
>
>
>
> --
> Stephen De Gabrielle
> s.degabrielle at ucl.ac.uk
> Telephone +44 (0)20 7679 5242 (x45242)
> Mobile                  079 851 890 45
> http://www.uclic.ucl.ac.uk/annb/MaSI.html
> University College London Interaction Centre
> Remax House - 31/32 Alfred Place
> London - WC1E 7DP
>
> "There's an old story about the person who wished his computer were as
> easy to use as his telephone.  That wish has come true, since I no
> longer know how to use my telephone. " -- Bjarne Stroustrup
>