ILOG OPL Development Studio Language Reference Manual

{Edge} Edges = {, , };int a[Edges] = [10,20,30];defines an integer array, a, indexed by a finite set of tuples. Its elements are a[],a[], and a[]. Tuples are described in detail in Tuples.Multidimensional arraysOPL supports the declaration of multidimensional arrays (see Data initialization about theellipsis syntax). For example, the declaration:int a[1..2][1..3] = ...;declares a two-dimensional array, a, indexed by two integer ranges. Indexed sets of differenttypes can of course be combined, as inint a[Days][1..3] = ...;which is a two-dimensional array whose elements are of the form a[Monday][1]. It isinteresting to contrast multidimensional and one-dimensional arrays of tuples.Consider the declaration:{string} Warehouses = ...;{string} Customers = ...;int transp[Warehouses,Customers] = ...;that declares a two-dimensional array transp. This array may represent the units shippedfrom a warehouse to a customer. In large-scale applications, it is likely that a given warehousedelivers only to a subset of the customers. The array transp is thus likely to be sparse, i.e.it will contain many zero values.The sparsity can be exploited by declarations of the form:{string} Warehouses ...;{string} Customers ...;tuple Route {string w;string c;}{Route} routes = ...;int transp[routes] = ... ;This declaration specifies a set, routes, that contains only the relevant pairs (warehouse,customer). The array transp can then be indexed by this set, exploiting the sparsity presentI L O G O P L D E V E L O P M E N T S T U D I O L A N G U A G ER E F E R E N C E M A N U A L25