Provide an initial solution to a dispatcher model using an external (csv) file

Technote (FAQ)


Question

How can I provide an initial solution to a dispatcher model using an external (csv) file?

Answer

The approach involves setting every visit to a particular vehicle using the IloRoutingSolution.setVehicle() method. The order of the visits that each vehicle makes in the user provided solution also needs to be specified between the vehicle's first and last visit (obtained via the IloVehicle.getFirstVisit() & IloVehicle.getLastVisit() calls respectively), using the IloRoutingSolution.setNext() method. Along with this the findFirstSolution goal needs to be modified to restore the solution provided by the user as such:

IloGoal goal = restoreSolution && instantiateCost;

Attached is a modified version of the pdp example (which comes with the distribution at <DispatcherXX>\examples\src) along with a csv file that defines an initial solution to the model.

In its current scheme, the csv file needs to provide a list of vehicle & visit combinations making sure that all the visits of a particular vehicle are contiguous so as to be compatible with the logic in the code. You may need to change the initPDP, nodeFileName, vehiclesFileName, visitsFileName variable values to match the location of the corresponding files on your file system.


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Document information


More support for:

IBM ILOG CP
Dispatcher:First Solution Algorithms

Software version:

1.5, 1.6

Operating system(s):

AIX, HP-UX, Linux, Solaris, Windows

Software edition:

All Editions

Reference #:

1573352

Modified date:

2012-10-31

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