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

[John J Forrest]

James,

I was not paying attention as I saw readLp and thought - that is nothing 
to do with Clp/OsiClp.

I will put readLp and writeLp into OsiClp.

John Forrest



"James Gibbons" <James.Gibbons at nottingham.ac.uk> 
Sent by: coin-discuss-bounces at list.coin-or.org
02/01/2006 09:27 AM
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Subject
[Coin-discuss] re: Preserving row and column names using readLP & 
OsiSolverInterface






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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