Re: [Pytables-users] WalkGroups To Instantiate leaves

[Ivan V. i B. <iv...@ca...>]

On Sun, Feb 27, 2005 at 03:24:36AM -0500, travlr wrote:
> Hi Francesc,
>=20
> The reference for walkGroups() says:=20
> Iterator that returns the list of Groups (not Leaves) hanging from where.
>=20
> From this description, the list returned should not include the "/"
> group if that is what is labled for where. -->walkGroups(where=3D"/")

Yes, you're right on that.  In fact, the documentation for
File.walkGroups() and Group._f_walkGroups() was fixed some time ago to
reflect that detail.  It will show up in PyTables 1.0.  If you want to
get the updated documentation, you can get a development snapshot from
PyTables at http://www.carabos.com/downloads/pytables/snapshots .

>=20
> The tutorial provides great & diverse examples of how to attain the
> public attributes of the object tree, but does not express how into
> instantiate the leaves, via iteration, so they can be used for numeric
> processing. For instance I'm trying to loop through the groups hanging
> from "root", to work with the arrays contained within.

You might be interested in File.listNodes() and File.walkNodes().  The
first lists direct children of a specific node.  The second recurses
into children to get all descendent nodes.

>=20
> One version I've tried:
>=20
> import tables as ta
> f  =3D ta.openFile('/H5/ESdat.h5','r')
>=20
> for group in f.walkGroups(where=3D"/"):
>     g =3D eval("f.root."+group._v_name)
      # You can directly use 'group' here instead of 'g'.
>     ap =3D g.AP.read()
>     aS =3D g.AS.read()
>     p1 =3D g.P1.read()
>     v1 =3D g.V1.read()
>     a1 =3D g.A1.read()
>     ud =3D g.UD.read()
>=20
> ... do some things...
> f.close()
>=20
> I've tried many possible ways to iterate through the file and
> auto-magically perform tasks.

A simple example of Group._f_listNodes():

	# For every group which descends from '/' (including it).
	for group in f.walkGroups('/'):
	    # For every leaf in that group.
	    for leaf in group._f_listNodes(classname =3D 'Leaf'):
	        print leaf._v_pathname, leaf.read()

Hope this helps.  Regards,
    Ivan


import disclaimer
--=20
Ivan Vilata i Balaguer   >qo<   http://www.carabos.com/
       C=E1rabos Coop. V.  V  V   Enjoy Data
                          ""