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Simulate a Relational Event Model (REM)

Source: R/simulate.R
rem.simulate.Rd

Simulate a Relational Event Model (REM)

Usage

rem.simulate(
  events = matrix(0, 0, 4),
  formula,
  coef = NULL,
  coef_degree = 0,
  n_events = 0,
  time = 0,
  max_events = 4e+05,
  n_nodes,
  verbose = FALSE,
  baseline = NULL,
  seed = 123,
  block = 1,
  directed = FALSE
)

Arguments

events

A matrix representing the initial events with columns time, from, to, and optionally type (1 for start, 3 for exogenous changes). Defaults to an empty 4-column matrix.

formula

A one-sided formula specifying the sufficient statistics to include in the intensity function. The right-hand side must be composed of terms from redeem_terms. For example: ~ inertia() + reciprocity() + degree. An intercept (~ 1) is the minimal specification.

coef

Numeric vector; coefficients for the model. Defaults to NULL.

coef_degree

Numeric; degree coefficient. Defaults to 0.

n_events

Integer; number of events to simulate. Defaults to 0.

time

Numeric; simulation time. Defaults to 0.

max_events

Integer; maximum number of events. Defaults to 400000.

n_nodes

Integer; the total number of actors in the network.

verbose

Logical; if TRUE, prints progress information. Defaults to FALSE.

baseline

Numeric vector; baseline intensity values for intervals defined by changepoints. Defaults to NULL.

seed

Integer; random seed. Defaults to 123.

block

An integer vector of length n_nodes indicating the block/group assignment for each node, or a single value applied to all nodes. Defaults to 1. If multiple blocks are assigned, within-block interactions are suppressed (i.e., their dyadic intensities are set to 0), meaning only events occurring between actors in different blocks are simulated.

directed

Logical; whether the interaction events are directed. Defaults to FALSE.

Value

A matrix of simulated events.

Details

The block parameter allows the user to specify a partition of the nodes into different groups (blocks). When the vector contains more than one unique block identifier:

  • The simulation suppresses all within-block dyad intensities by setting them to 0.

  • Consequently, only events between nodes belonging to different blocks are generated (between-block interactions).

  • If all nodes belong to the same block (e.g., if a single value or NULL is passed), no block-level constraints are applied, and all dyads are simulated according to the specified model formula.

Note

Multi-stream event models are currently not supported in simulation.

Examples

# Simulate events from a REM model structure
n <- 10
f1 <- ~ 1 + inertia(transformation = "identity")

# Simulating events
evs <- rem.simulate(
  formula = f1,
  n_nodes = n,
  time = 1.0,
  coef = c(1.0, 0.5),
  seed = 42,
  max_events = 100
)
head(evs)
#>            [,1] [,2] [,3]
#> [1,] 0.02256350    5   10
#> [2,] 0.05180009    2    8
#> [3,] 0.05909043    5    9
#> [4,] 0.07507357    3    5
#> [5,] 0.07526190    1    8
#> [6,] 0.09287949    2    6