[Coin-discuss] re: Preserving row and column names using readLP & OsiSolverInterface

[James Gibbons]

Dear All,

Replying to myself about previous message (text at end). Investigating further I don't think the OsiSolverInterface::readLp function, inherited by OsiClpSolverInterface copies the neames into the Solver object. I've fixed this problem for me locally by adding the following  function to OsiClpSolverInterface.cpp (and a corresponding declaration in OsiClpSolverInterface.hpp). the function is adapted from OsiSolverInterface::readLp and OsiClpSolverInterface::readMps. I guess there maybe a more elegant way of doing this as the message handler stuff doesn't work and CoinLpIO::readLp doesn't return the number of errors. Is there any chane of getting this or an improved version included in the code base?

Thanks,

James 

int
OsiClpSolverInterface::readLp(const char * filename, const double epsilon)
{
  
  // Get rid of integer stuff
  delete [] integerInformation_;
  integerInformation_=NULL;

  CoinLpIO m;
  m.setInfinity(getInfinity());
  //m.passInMessageHandler(modelPtr_->messageHandler());
  //*m.messagesPointer()=modelPtr_->coinMessages();
  
  //handler_->message(COIN_SOLVER_MPS,messages_)
  //  <<m.getProblemName()<< numberErrors <<CoinMessageEol;
  int numberErrors = 0;
  m.readLp(filename, epsilon);

  if (!numberErrors) {
	  // set objective function offest
	  setDblParam(OsiObjOffset, 0);

	  // set problem name
	  setStrParam(OsiProbName, m.getProblemName());

	  // no errors
	  loadProblem(*m.getMatrixByCol(),m.getColLower(),m.getColUpper(),
		m.getObjCoefficients(),m.getRowSense(),m.getRightHandSide(),
		m.getRowRange());

	  const char *integer = m.integerColumns();
	  int nCols = m.getNumCols();
	  int nRows = m.getNumRows();
	  if (integer) {
		int i, n = 0;
		int *index = new int [nCols];
		for (i=0; i<nCols; i++) {
		  if (integer[i]) {
		index[n++] = i;
		  }
		}
		setInteger(index,n);
		delete [] index;
	  }

	  // Always keep names
	  int iRow;
      std::vector<std::string> rowNames = std::vector<std::string> ();
      std::vector<std::string> columnNames = std::vector<std::string> ();
      rowNames.reserve(nRows);
      for (iRow=0;iRow<nRows;iRow++) {
		const char * name = m.rowName(iRow);
		rowNames.push_back(name);
	  }
    
      int iColumn;
      columnNames.reserve(nCols);
      for (iColumn=0;iColumn<nCols;iColumn++) {
		const char * name = m.columnName(iColumn);
		columnNames.push_back(name);
      }
      modelPtr_->copyNames(rowNames,columnNames);
  }
  return numberErrors; 

Dear all,

I am trying to use the Clp and Cbc solvers to solve a problem generated by XpressMP Mosel. I have been able to read and solve the problem as a .lp file but not using a .mps file. (I think Xpress mps files might have a non-standard extension to the format?).

What I can't work out how to do is too keep the row and column names from the original problem. A simple example:

    OsiClpSolverInterface solver0;
    std::string fn = "test2.lp";
    solver0.readLp(fn.c_str());
    int ncols = solver0.getNumCols();
    for(int i=0;i<ncols;i++) {
		std::cout<<solver0.getColName(i)<<"\n";}

This outputs the column names as C0000001 etc. As there is no guarantee  about what order Mosel generates the matrix in I really need access to the names. I've tried recompiling with LPIO_DEBUG defined in the CoinLPIO.cpp file and the output from this suggests that readLp is reading in the problem names correctly. So am I missing something obvious or doing something wrong?

Thanks,

James

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