Originally posted by: Emmaqwy

 IloRange[] rows;

rows = lp.getRanges();

rows[row].clearExpr();

I want to clear some rows's expression , I called IloRange.clearExpr() , but it is not efficient.

Anyone knows a faster function to clear constraint expression?

Originally posted by: Emmaqwy

I also try to use IloLPMatrix::removeRows, call one time , and remove about 11496 rows, but it cost about  5 min. Still need to find a faster way... 

Did you try removing the IloLPMatrix instance from the IloCplex instance before modifying it?

What is the percentage of rows you keep? Maybe it is faster to just remove everything and then re-add the things you want to keep.

Can you share an example code that illustrates this slow removal?