NETWORK Procedure
BY Statement
BY variables;
You can specify a BY statement in PROC NETWORK to obtain separate analyses of observations in groups that are defined by the values of the BY variables. If you specify more than one BY statement, only the last one that you specify is used. For more information, see the discussion of BY-group processing in the "Grouping Data" section of SAS Programmers Guide: Essentials.
The specified BY variables must come from the LINKS= data table. The BY statement in PROC NETWORK is not supported when multiple input data tables are used. Two examples of using BY-group processing are shown in Centrality Metrics for an Undirected Graph by Community and Shortest Path in a Road Network by Date and Time.
All parameter settings apply to each individual group independently (not to the entire process as a whole). For example, when a stopping criterion such as the MAXTIME= option is specified for a particular algorithm, this limit pertains to each individual group as it is processed.