Network Optimization Action Set

This section contains PROC CAS code.

Note: Input data must be accessible in your CAS session, either as a CAS table or as a transient-scope table. A CAS table has a two-level name: the first level is your CAS engine libref, and the second level is the table name. You refer to this table in the CAS procedure by specifying only the second level. For more information about two-level names, see Chapter 1, Introduction (SAS Optimization: The OPTNETWORK Procedure). A transient-scope table is called directly from the action and exists in memory for the duration of the action. For more information about accessing data, see SAS Viya: System Programming Guide. For more information about PROC CAS and programming in CASL, see SAS Cloud Analytic Services: CASL Programmer’s Guide and SAS Cloud Analytic Services: CASL Reference.

As an example, consider the weighted undirected graph in Figure 13.

Figure 13: An Undirected Graph

The links data set can be represented as follows:

data LinkSetIn;
   input from $ to $ weight @@;
   datalines;
A B  7  A D  5  B C 8  B D 9  B E 7
C E  5  D E 15  D F 6  E F 8  E G 9
F G 11  H I  1  I J 3  H J 2
;

The following DATA step loads the LinkSetIn data set into a CAS data table named mycas.LinkSetIn. These statements assume that the CAS engine libref is named mycas, but you can substitute any appropriately defined CAS engine libref.

data mycas.LinkSetIn;
   set LinkSetIn;
run;

The following statements calculate a minimum spanning forest and output the results in the data table MinSpanForest:

proc cas;
   loadactionset "optNetwork";
   action optNetwork.minSpanTree result=r status=s /
      links = {name = "LinkSetIn"}
      out   = {name = "MinSpanForest", replace = true};
   run;
   print r.ProblemSummary; run;
   print r.SolutionSummary; run;
   action table.fetch / table = "MinSpanForest"; run;
quit;

The problem summary output from this action is shown in Output 2.11.1.

The solution summary output from this action is shown in Output 2.11.2.

The output data table MinSpanForest now contains the links that belong to a minimum spanning forest, shown in Output 2.11.3.

The minimal cost links are shown in green in Figure 14.

Figure 14: Minimum Spanning Forest