[Coin-discuss] Osi and Add/Delete rows

[Jonathan Eckstein]

In developing PICO, which uses OSI, we assume the behavior you describe 
and use a splay tree data structure to track the row numbers.  When we 
insert a row, it gets a unique ID by incrementing a counter.  The splay 
tree can quickly calculate the cardinality of any value in the set of 
currently loaded rows, and that gives its position within the solver.

But since I am not an OSI or solver author, I cannot speak with complete 
authority.

   -- Jonathan


Jan-Willem Goossens wrote:

> Hi all,
> 
> I have a question about adding and deleting rows through the
> osisolverinterface layer.
> 
> I start with loading my problem with loadProblem. After that, of course,
> the actual adding or deleting of a row is no problem; just calling addRow
> or deleteRow works fine.
> 
> My problem is with the offsets (index numbers) of the old and new rows.
> Since I can only retreive, for example, price info for a particular row
> with getRowPrice() if I know the index of the row I'm interested in, it's
> crucial that, in case of some deleted rows, I can update my recorded index
> numbers.
> 
> One way for me to do this accounting would be to assume that if I remove
> row i, then all rows j > i will all be moved 'back' one position. But this
> would depend on the implementation of the deleteRow on the solver-specific
> side. For additions, I guess it's OK to assume they will be added 'at the
> end'.
> 
> Or is there a completely different way around this problem?
> 
> Thanks in advance,
> 
> Jan-Willem
> 
> 
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