[kepler-users] Iterating over Elements / Looping

[Edward A. Lee]

Note that IterateOverArray is demos at:

   $PTII/actor/lib/hoc/demo/IterateOverArray/IterateOverArray.xml

There is also RunCompositeActor, which can be used to have a model
run repeatedly to completion. Demo here:

   $PTII/actor/lib/hoc/demo/MultipleRuns/MultipleRuns.xml

Consitionally executing a model is demod here:

   $PTII/actor/lib/hoc/demo/Case/Case.xml

Parallel execution over a parameterized number of channels is
shown here:

   $PTII/actor/lib/hoc/demo/HocDE/HocDE.xml

and

   $PTII/actor/lib/hoc/demo/DFTSubSet/DFTSubSet.xml

Applying a function defined in the expression language to
a subsequence of the input is shown here:

   $PTII/actor/lib/hoc/demo/ApplyFFT/ApplyFFT.xml

Edward


On 5/1/12 9:00 PM, Christopher Brooks wrote:
> Hi Stefan,
> We talked about these sorts of model today. Edward's main comment was
> that we need to have better documentation about how to do control flow
> with actor-oriented models. Also, we talked about using IterateOverArray
> for the sorts of models, which is probably your best bet.
>
> My brute force method would be to have write an actor that read a
> directory and produced a file or directory on the output each time the
> actor was fired. When all the files and/or directories had been written
> to the output, then prefire() would return false. An even more brute
> force method would be to have a separate output that would be written to
> when the directory had been completely read. This output could be
> connected to a Stop actor.
>
> _Christopher
>
> On 4/30/12 1:07 AM, Stefan Proell wrote:
>> Dear Christopher,
>> thanks for the hints.
>> I do not know the size of the array in advance and I also need to
>> terminate the looping in a reliable way. There hopefully exists a more
>> elegant solution to this problem, but I now decided to model the
>> process in a way it stays dynamic regarding the array size and
>> terminating after hitting a counter-limit. I attach the project file
>> to this mail. What this simple example does is fetching a directory of
>> files (MP3s) and storing it on my local hard drive for further
>> processing (not implemented yet :-) ). I used a DDF director.
>>
>> Kind regards,
>> Stefan
>>
>>
>> Am 2012-04-26 16:54, schrieb Christopher Brooks:
>>> Stefan,
>>> DirectoryListing produces an Array an output.
>>> If you know the number of files in the directory in advance, then you
>>> can use ArrayToSequence and have a SDF Director.
>>> The reason you need to know the number of files is because you need
>>> to know the size of the array so that SDF can calculate a schedule.
>>> An alternative is to set the allowRateChanges in SDFDirector to true,
>>> see DirectorySDFRateChange.xml
>>> One issue with this model is that it does not terminate naturally.
>>>
>>> Or, you can use the PN Director and terminate the model with a test
>>> that looks for a file name that has already been seen.
>>>
>>> An alternative is to put the DirectoryListing inside a Composite that
>>> has a SDF Director. I ran in to issue with terminating the model
>>> though. Attached is DirectoryListing2.xml.
>>>
>>> I'm probably missing an easier way to do this though.
>>>
>>> See also
>>> https://kepler-project.org/users/faq#how-do-i-branch
>>>
>>> _Christopher
>>>
>>> On 4/26/12 7:29 AM, Tomasz Żok wrote:
>>>> Dear Stefan,
>>>>
>>>> please take a look at this tutorial session:
>>>> http://scilla.man.poznan.pl:8080/confluence/x/oAFU
>>>>
>>>> You can jump straight to sections dedicated to looping in Kepler,
>>>> there are
>>>> several possible solutions presented.
>>>>
>>>> Best regards,
>>>> Tomek
>>>>
>>>>> Dear Kepler Community, I am rathre new to Kepler and I have a
>>>>> question regarding looping. I searched the documentation and the
>>>>> mailing list archive, but could not find a proper answer. For a
>>>>> specific workflow, I need to fetch several files from a Web server
>>>>> and process these. For this purpose, I use the DirectoryListing -
>>>>> Actor. Fetching the URLs of the files works fine, but how would I
>>>>> iterate over all the URLs for further processing? I would like to
>>>>> use the "URL to File" actor, but how would I iterate over the
>>>>> elements/URLs I receive? Is there an elegant way, or do I have to
>>>>> assemble (rather complicated) loops just for going through all the
>>>>> elements? So far I would use the Actor ArrayElement, but then I
>>>>> have to feed an index variable to it, which I would have to iterate
>>>>> after each token. This seems to be a bit of an overhead to me.
>>>>> Thanks in advance, Kind regards, Stefan
>>>
>>>
>>>
>>
>
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