[Cmpl] question on syntax for nested loops in cmpl

[Thomas Schleiff]

You have a wrong semicolon in your nested loop.

You must consider the difference between expressions and statements, as 
common in programming languages. "sum { i in export_ports: 
route_tonnage[[i, m], j,k] }" is an expression, so a semicolon before 
the closing curly bracket would be wrong. But "import_tonnage[m,j,k]=sum 
{ i in export_ports: route_tonnage[[i, m], j,k] };" is a statement, so 
the semicolon at the end of it is correct.

Thomas Schleiff


Am 11.10.2017 um 17:44 schrieb Richard Males:
>
> I am currently interested in the syntax for assigning a sum within a 
> loop, in effect a nested loop.  I have sets of import and export ports 
> and routes defined on them (thanks to Thomas Schlieff for help on 
> specifying the routes):
>
> export_ports := set("Santos","NewOrleans","Seattle");
> import_ports:= set("ChinaIP", "EuropeIP", "MexicoIP", "JapanIP", 
> "SoutheastAsiaIP","FSU-MiddleEastIP","KoreaIP");
> routes := [export_ports, import_ports];
> and variables
> route_tonnage[routes,seasons,grains]:real[0..];
>
> export_tonnage[export_ports,seasons,grains]:real[0..];
>
> import_tonnage[import_ports,seasons,grains]:real[0..];
>
>
> Using this framework, I want to be able to determine the total 
> quantity coming in from all routes to an import port as an 
> intermediate variable.  I also have indices of seasons (1 to 4) and 
> grains (currently only "Soybeans").  I am able to do this by 
> enumerating for each import port, season, and grain, as follows, but 
> if I try to generalize to loop over the set of import ports so that I 
> don't need to repeat my lines, I get syntax errors.
>
> import_tonnage["ChinaIP",1,"Soybeans"]=sum { i in export_ports: 
> route_tonnage[[i, "ChinaIP"], 1,"Soybeans"] };
>
> import_tonnage["ChinaIP",2,"Soybeans"]=sum { i in export_ports: 
> route_tonnage[[i, "ChinaIP"], 2,"Soybeans"] };
>
> import_tonnage["ChinaIP",3,"Soybeans"]=sum { i in export_ports: 
> route_tonnage[[i, "ChinaIP"], 3,"Soybeans"] };
>
> import_tonnage["ChinaIP",4,"Soybeans"]=sum { i in export_ports: 
> route_tonnage[[i, "ChinaIP"], 4,"Soybeans"] };
>
> import_tonnage["EuropeIP",1,"Soybeans"]=sum { i in export_ports: 
> route_tonnage[[i, "EuropeIP"], 1,"Soybeans"] };
>
> import_tonnage["EuropeIP",2,"Soybeans"]=sum { i in export_ports: 
> route_tonnage[[i, "EuropeIP"], 2,"Soybeans"] };
>
> import_tonnage["EuropeIP",3,"Soybeans"]=sum { i in export_ports: 
> route_tonnage[[i, "EuropeIP"], 3,"Soybeans"] };
>
> import_tonnage["EuropeIP",4,"Soybeans"]=sum { i in export_ports: 
> route_tonnage[[i, "EuropeIP"], 4,"Soybeans"] };
>
> I want to do something like:
>
> {m in import_ports,j in seasons, k in grains: 
> import_tonnage[m,j,k]=sum { i in export_ports: route_tonnage[[i, m], 
> j,k];};}
>
>
> but this yields error messages relating to the double-nested curly braces.
>
> Any suggestions as to a simplifying approach would be appreciated.  
> Thanks in advance.
>
> Dick Males
>
>
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