The problem is that I have 500 stores and 5 products, so a combo of 2500 time-series models.. but when I try to fill in the gaps using the above 'expand' code, I end up with 490 stores and 5 products.. something like this: Store Date Price Product A 2000.01 234 A1 A 2000.02 246 A1 A 2000.03 258 A1 B 2000.01 564 B2 B 2000.02 534 B2 B 2000.03 533 B2 B 2000.01 345 B1 B 2000.02 354 B1 C 2005.03 356 C2 C 2005.04 367 C2 C 2005.05 359 C2 .. and so on.....(there are alos many other variables attached, just didn't specify them down)..
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