ILOG CPLEX / OPL dynamic Excel sheet referencing

问题

I'm trying to dynamically reference Excel sheets or tables within the .dat for a Mixed Integer Problem in Vehicle Routing that I'm trying to solve in CPLEX (OPL).

The setup is a: .mod = model, .dat = data and a MS Excel spreadsheet

I have a 2 dimensional array with customer demand data = Excel range (for coding convenience I did not format the excel data as a table yet)

The decision variable in .mod looks like this:

dvar boolean x[vertices][vertices][scenarios]

in .dat:

vertices from SheetRead (data, "Table!vertices"); and

scenarios from SheetRead (data, "dont know how to yet"); this might not be needed

without the scenario Index everything is fine. But as the demand for the customers changes in this model I'd like to include this via changing the data base reference. Now what I'd like to do is one of 2 things:

Either: Change the spreadsheet in Excel so that depending on the scenario I get something like that in .dat:

scenario = 1:

vertices from SheetRead (data, "table-scenario-1!vertices");

scenario = 2:

vertices from SheetRead (data, "table-scenario-2!vertices");

so changing the spreadsheet for new base data, or: Change the range within the same spreadsheet:

scenario = 1:

vertices from SheetRead (data, "table!vertices-1");

scenario = 2:

vertices from SheetRead (data, "table!vertices-2");

either way would be fine.

Knowing how 3D Tables in Excel are created using multiple spreadsheets with 2D Tables grouped, the more natural approach seems to be, to have vertices always reference the same range in every Excel spreadsheet while depending on the scenario the spreadsheet/page is switched, but I just don't know how to.

Thanks for the advice.

回答1:

Unfortunately, the arguments to SheetConnection must be a string literal or an Id (see the OPL grammar in the user manual here). And similarly for SheetRead. This means, you cannot have dynamic sources for a sheet connection.

As we discussed in the comments, one option is to add an additional index to all data: the scenario. Then always read the data for all scenarios and in the .mod file select what you want to actually use.

回答2:

at https://www.ibm.com/developerworks/community/forums/html/topic?id=5af4d332-2a97-4250-bc06-76595eef1ab0&ps=25 I shared an example where you can set a dynamic name for the Excel file. The same way you could have a dynamic range, the trick is to use flow control.

sub.mod

float maxOfx = 2;
string fileName=...;
dvar float x;

maximize x;
subject to {
  x<=maxOfx;
}

execute
{
 writeln("filename= ",fileName);
}

and then the main model is

main {
  var source = new IloOplModelSource("sub.mod");
  var cplex = new IloCplex();
  var def = new IloOplModelDefinition(source);
  var opl = new IloOplModel(def,cplex);


  for(var k=11;k<=20;k++)
  {
  var opl = new IloOplModel(def,cplex);

  var data2= new IloOplDataElements();
  data2.fileName="file"+k;
  opl.addDataSource(data2);
  opl.generate();

  if (cplex.solve()) {
     writeln("OBJ = " + cplex.getObjValue());
  } else {
     writeln("No solution");
  }
  opl.postProcess();
 opl.end();


}  

}

来源：https://stackoverflow.com/questions/59074711/ilog-cplex-opl-dynamic-excel-sheet-referencing

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