ergmx.S

ergmx.S(formula, attrs)

Evaluate formula on a subgraph, as ergm’s S().

attrs is an R formula of the vertex attributes, as a string. One-sided, it picks the vertices of an induced subgraph: "~level == 'individual'" gives the network among individuals (directed if the network is). Two-sided, it picks two disjoint sets, and the formula is evaluated on the undirected bipartite network of the ties between them (in a directed network, of the arcs from the first set to the second, as ergm), whose first mode (b1 terms) is the left-hand set: "(level == 'individual') ~ (level == 'organization')". Each side may also be a boolean array or 1-based vertex indices. In a formula string: "S(~edges + gwesp(0.5, fixed=TRUE), ~level == 'individual')". Names: S(level=="individual")~edges, as in ergm.