david.bri...@ubs.com said the following on 10/25/2010 12:19 PM:
> I currently have 160 or so tables with attributes on. I wish to find the
> all the tables with a certain set of attributes. This code is running a
> little slow:
>
> def getTables(tsdb, attributes):
> answer = []
> for node in tsdb:
> if isinstance(node, pytables.Leaf):
> matches = True
> for items in attributes.items():
> if not node.attrs.__contains__(items[0]):
> matches = False
> break
> if node.attrs.__getattr__(items[0]) <> items[1]:
> matches = False
> break
> if matches: answer.append(node)
> return answer
A few suggestions:
1) Instead of
for node in tsdb:
if isinstance(node, pytables.Leaf):
consider using
for node in tsdb.walkNodes('/', classname='Leaf')
or (maybe better)
for node in tsdb.walkNodes('/', classname='Table')
This way you get the nodes you need without having to introspect to see if
they're of the proper class.
2) Within your nested loop you call attributes.items() each time. You only
need to do this once, so I recommend binding the value of items() to a local
variable before entering the outer loop:
attrItems = attributes.items()
for node in tsdb.walkNodes(...): ...
3) Next, the so-called 'double under' methods (__contains__(), __getattr__())
are generally intended for internal use only by their containing objects. A
better way would be to use the 'in' operator; to wit (note also the binding of
node.attr.items()):
nodeAttrItems = node.attrs.items()
if attrItems[0] not in nodeAttrItems: ...
if nodeAttrItems[0] <> attrItems[1]: ...
Also if you did this you can eliminate your innermost loop.
--
David E. Sallis, Senior Principal Engineer, Software
General Dynamics Information Technology
NOAA Coastal Data Development Center
Stennis Space Center, Mississippi
228.688.3805
david.sal...@gdit.com
david.sal...@noaa.gov
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