[Halld-offline] reducing file sizes

[Richard Jones]

Blake,

All of the MC information about the event that was simulated is stored 
in the <reaction> tag.  The <mctrajectory> tag only contains cheat 
information about actual tracks going through the detector.  I didn't 
write the DMCThrown class, but The term "MCThrown" would suggest that it 
is only concerned with the original vertex, not with what paths the 
particles took subsequently as they traversed the detectors.  So I would 
say that you can wipe out the <mctrajectory> tag and see no effect in 
the calorimeter reconstruction.

-Richard J.



Blake Leverington wrote:
> ok, I think maybe I wasn't clear or there's something I don't 
> understand. Since I'm doing background MC work I need to know what 
> particle types and reactions pass my reconstruction cuts so I still 
> probably need  <mctrajectory> tag. I assume this is where the DMCThrown 
> information comes from.  But I was also under the impression that 
> <reaction> contains information about the vertex and so on for 
> reconstructing angles.
>
> -Blake
>
> Richard Jones wrote:
>   
>> Blake,
>>
>> The rules are simple: just cut out entire tags (anything goes) to kill 
>> what you don't want.  I think this is too clear to risk mistakes.  
>> Simply if you kill a tag then all of its contents disappear with it.  
>> It sounds to me like you still want to kill the <reaction> ... 
>> </reaction> tag and the <mctrajectory>..</.mctrajectory> tag.  After 
>> that, you are down to basically just what you want.
>>
>> -Richard J.
>>
>> Blake Leverington wrote:
>>     
>>> Hi Richard,
>>>
>>> Ok, I followed your instructions and everything went smoothly, so 
>>> thank you. I ended up with a 70% reduction in my files sizes, 165MB 
>>> down to 51MB. I've attached my edited hddm header file, could you 
>>> take a quick look to see if there is anything else I could cut out? I 
>>> think I took out everything unwanted, I think,  but I'm not familiar 
>>> enough with the hddm formatting.  All I require is photon 
>>> reconstruction in the FCAL and BCAL and the truth information.
>>>
>>> Cheers,
>>> -Blake
>>>
>>>   
>>>       

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