ufl team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Anders Logg wrote:
> On Mon, Jan 25, 2010 at 03:09:06PM +0000, Garth N. Wells wrote:
>>
>> Anders Logg wrote:
>>> On Mon, Jan 25, 2010 at 03:19:36PM +0100, Marie Rognes wrote:
>>>> noreply@xxxxxxxxxxxxx wrote:
>>>>> ------------------------------------------------------------
>>>>> revno: 892
>>>>> committer: Anders Logg <logg@xxxxxxxxx>
>>>>> branch nick: ufl-main
>>>>> timestamp: Mon 2010-01-25 13:26:37 +0100
>>>>> message:
>>>>>  Add function sort_elements for sorting elements backwards with nested sub
>>>>>  elements first. Using pygraph library for sorting directed acyclic graph.
>>>>> modified:
>>>>>  ufl/algorithms/__init__.py
>>>>>  ufl/algorithms/analysis.py
>>>>>
>>>>>
>>>> Is pygraph super-standard?
>>> I don't know but it's in Ubuntu... :-)
>>>
>>> It was the simplest way I could find to store a list of elements based
>>> on their dependencies to sub elements.
>>>
>>> If it's a problem, we could implement the sorting ourselves.
>>>
>> If it's simple, I would suggest implementing it ourselves to avoid a
>> dependency since UFL didn't have any dependencies beyond the standard
>> Python modules. It can wait until until the UFL/FFC change are complete
>> though.
> 
> You mean like tomorrow?
> 

If you are quick enough to have UFL and FFC ready tomorrow, then writing
a graph library should only take a few minutes ;).

Garth

> If anyone has a simple piece of code to do the following, let me know:
> 
>   # Create directed graph
>   g = digraph()
> 
>   # Add nodes (elements)
>   for element in elements:
>       g.add_node(element)
> 
>   # Add edges (dependencies)
>   for element in elements:
>       for sub_element in element.sub_elements():
>           g.add_edge(element, sub_element)
> 
>   # Sort graph
>   sorted_elements = topological_sorting(g)
> 
> --
> Anders