[Scip] How to access a subscip in ObjPricer::scip_redcost?

[Gerald Gamrath]

Hi Sebastian,

as Timo suggested, everything that you would put into a pricerdata in C, 
you should add as global object variables in C++.
The pricerdata is needed to store the C++ wrapper class, so if you 
overwrite it, your objpricer gets lost.

Yes, there is also a method SCIPsetProbData() for setting your problem 
data in a C code. However, in C++, you are again not allowed to use the 
SCIP_PRICERDATA*, but should instead store all needed data as global 
object variables in your objprobdata. You can set the objprobdata if you 
create your problem with the method SCIPcreateObjProb() instead of 
SCIPcreateProb().

Merry christmas,
Gerald

Sebastian Ruther schrieb:
>   Hello,
>
> well it works the way you suggested. However, I found out that the 
> general problem is with the PricerData. I can't access it anywhere but 
> the function in which I call the constructor:
>
> PricerDataCG* pPricerDataCG = new PricerDataCG(iAc->second);
> for which I define struct PricerDataCG : public SCIP_PricerData.
>
> I guess I need to tell scip that a pricer data exists:
> SCIPpricerSetData(pricer, pPricerDataCG);
> However, if I do this I get an unexpected exception error for line
> SCIP_CALL( pricerdata->objpricer->scip_redcost(scip, pricer, lowerbound, 
> result) );     in solve.c
> the debugger tells me that objpricer doesn't know function scip_redcost.
>
> If I exclude SCIPpricerSetData it compiles and runs fine but like I said 
> I can't use the pricerdata anywhere else.
>
> So what's the correct way to initialize/add a pricerdata object?
>
> BTW: is there an equivalent of SCIPpricerSetData probdata?
>
> Merry christmas
> Sebastian
>
>
> On 22/12/2010 10:05 PM, Timo Berthold wrote:
>   
>> Hi Sebastian.
>>
>> In C, you would put this into the private data struct SCIP_PricerData. In C++,
>> however, you can just define a SCIP* subscip as global object variables.
>>
>> Also see the doxygen HowTo for private data in pricers:
>> http://scip.zib.de/doc/html/PRICER.html#PRICER_DATA
>> and compare lines 122-131 of examples/VRP/src/priver_vrp.h
>> which is written in C++
>>
>> Merry Xmas to downunder,
>> Timo
>>
>>
>> Am Mittwoch 22 Dezember 2010, 07:33:09 schrieb Sebastian Ruther:
>>     
>>>    Hello,
>>>
>>> I'm implementing a Branch-and-Price algorithm. In the examples the
>>> variables are always generated by the subscip which is generated in the
>>> ObjPricer::scip_redcost call. However, I don't want to generate the
>>> subscip problem in every iteration so I generate my subscip in
>>> ObjPricer::initsol by calling
>>> SCIP*      subscip = NULL;
>>> SCIP_CALL( SCIPcreate(&subscip) );
>>> SCIP_CALL( SCIPincludeDefaultPlugins(subscip) );
>>> SCIP_CALL( SCIPcreateProb(subscip, PricingNameBuf.str().c_str(), 0, 0,
>>> 0, 0, 0, 0, 0) );
>>>
>>> How do I access the SCIP* subscip in the ObjPricer::scip_redcost
>>> function? The parameter list only gives me the SCIP* scip which refers
>>> to the master problem.
>>>
>>> Thanks
>>> Sebastian
>>> _______________________________________________
>>> Scip mailing list
>>> Scip at zib.de
>>> http://listserv.zib.de/mailman/listinfo/scip
>>>       
>> .
>>
>>     
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