[Help-glpk] Ordered bin packing

[Dmitri Goutnik]

Hello everyone,

I modified bpp.mod to pack items in predefined number of bins of unlimited 
capacity so that weight is (approximately) evenly distributed between bins. In 
addition to weight, each item has an "order" or "position". Is there a way to 
write an additional model constraint so that items are preferably packed in 
compact order, e.g. items with sequential positions should go to the the same 
container? For example, for this solution:

Bin 1: total weight 110
        item 1 (40)
        item 4 (70) <--

Bin 2: total weight 90
        item 5 (50)
        item 6 (40)

Bin 3: total weight 130
        item 2 (60) -->
        item 3 (30)
        item 7 (15)
        item 8 (25)

is there a way to add such constraint so item 2 would preferably be packed to 
bin 1?

Thanks,
Dmitri