Decision Optimization

Decision Optimization

Delivers prescriptive analytics capabilities and decision intelligence to improve decision-making.


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Assigning values to a data element

  • 1.  Assigning values to a data element

    Posted 02/04/08 07:17 PM

    Originally posted by: SystemAdmin


    [aroso said:]

    Hi,

    Is it possible to change the value of a specific data element without having to reload the entire data file and generating the new model?
    #CPLEXOptimizers
    #DecisionOptimization


  • 2.  Re: Assigning values to a data element

    Posted 02/08/08 03:56 AM

    Originally posted by: SystemAdmin


    [EdKlotz said:]

    > Is it possible to change the value of a specific data element without having to > reload the entire data file and generating the new model?

    That depends on how you are calling CPLEX and the format of the file. 
    For example, if you are reading in an MPS, LP or SAV file into interactive CPLEX,
    you can use various 'change' commands to change a single matrix coefficient,
    right hand side value, objective value, or essentially any other problem data value.  Similarly, from any of the APIs, you have the ability to modify problem data vectors using functions like CPXchgcoef(), CPXchgsense(), IloRange::setLinearCoefs(), IloNumVar::setLB(), and so on.

    On the other hand, if you have a raw data file that doesn't relate directly to the problem data vectors that CPLEX ultimately sees, and you perform intermediate
    computations on that data (either through your own program or a modeling language like OPL, MPL, GAMS, AMPL, AIMMS, etc.), then you won't be able to modify it once CPLEX sees the problem unless you maintain some sort of mapping
    between the final problem data vectors CPLEX sees and the original raw data.
    Typically that would be a complex, if not impossible, task.
    #CPLEXOptimizers
    #DecisionOptimization