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Re: Problem using files with Cluster and CalorimeterHit collections [message #1747 is a reply to message #1745] Fri, 29 May 2009 08:57 Go to previous messageGo to previous message
Messages: 13
Registered: March 2006
Location: DESY, Hamburg
Hi Andre,

as far as I can see, there is no obvious solution to this problem.
So the short answer probably is the following: If you have an collection of clusters with links to calorimeter hits you cannot drop the collections containing the calorimeter hits without corrupting the output file.

So for the time being the only way to allow users to drop the calorimeter hits would be to ask Mark Thomson to add an steering parameter to PandoraPFA. If one could remove all the XXX.addHit() calls for the calorimeter clusters with a PandoraPFA steering parameter, one could safely drop the calorimeter hit collection.

The long answer to this problem, would state that fixing this problem on the basis of (the c++ implementation) of LCIO is quite difficult. SIO (the current low level file i/o format of LCIO) relays on the fact that all objects that are pointed at by other objects are written to the file. In this case the cluster objects point to some calorimeter hits. If you drop (i.e. don't write) these hits the file gets corrupted. The main problem is due to the fact, that LCIO cannot easily check whether the hits, which the clusters point to are written to the output file, because the clusters don't have the information in which collections the corresponding hits live.
The only rather quick workaround on LCIO level for this problem would be an option to remove all calorimeter hits of the clusters before writing the clusters to the file.

Usually, I would suggest to post this issue to the LCIO bug tracker (, however even critical bugs in the c++ part of the bug tracker are currently ignored, which sheds quite a bad light on the current support situation of LCIO.
Maybe this requires some discussion on a "non-software" level.

Cheers, J.
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