BuildDMI: Build Data Model Instance

In ggdmcModel: Model Builders for 'ggdmc' Package

Build Data Model Instance

Description

Constructs a Data Model Instance (DMI) from data and model specifications. The DMI builder can handle different model types including the Linear Ballistic Accumulator, the Diffusion Decision and hyperparameter. The process of building a 'hyperparameter' DMI amounts to constructing a joint distribution over conventional statistical models.

Usage

BuildDMI(data, model)

Arguments

data	A data frame to be converted to a DMI object.
model	A model specification object of class model containing parameters, and other model-specific information. This is typically created using the 'BuildModel' function.

Value

A 'dmi' object or a list of 'dmi' objects (multiple subjects), with structure:

• For choice RT models: Returns a named list of 'dmi' objects (one per subject)

• For hyperparameter models: Returns a single 'dmi' object

Each 'dmi' object contains:

• 'model' - The model specification

• 'data' - The processed data (a list)

• 'node_1_index' - Index mapping for first nodes (LBA only)

• 'is_positive_drift' - A logical vector indicating drift directions. For the LBA model, each element corresponds to an accumulator. For the DDM, each element represents a condition. In the DDM, a positive drift direction corresponds to a correct response (i.e., the accumulator reaches the upper bound), and vice versa.

Model Types Supported

'"lba"'

Linear Ballistic Accumulator model

'"hyper"'

Hyperparameter model

'"fastdm"'

Diffusion Decision model

Examples

# Hyperparameter model example
hyper_model <- BuildModel(
    p_map = list(A = "1", B = "1", mean_v = "M", sd_v = "1", st0 = "1", t0 = "1"),
    match_map = list(M = list(s1 = "r1", s2 = "r2")),
    factors = list(S = c("s1", "s2")),
    constants = c(sd_v = 1, st0 = 0),
    accumulators = c("r1", "r2"),
    type = "hyper",
    verbose = FALSE
)

# LBA model example
model <- BuildModel(
    p_map = list(A = "1", B = "1", t0 = "1", mean_v = "M", sd_v = "1", st0 = "1"),
    match_map = list(M = list(s1 = "r1", s2 = "r2")),
    factors = list(S = c("s1", "s2")),
    constants = c(st0 = 0, sd_v = 1),
    accumulators = c("r1", "r2"),
    type = "lba"
)

dat <- data.frame(
  RT = c(0.7802726, 0.7890208, 1.3222672, 0.8376305, 0.7144698),
  R  = c("r1", "r1", "r2", "r1", "r1"),
  s  = c(1, 1, 1, 1, 1),
  S  = c("s1", "s1", "s1", "s1", "s1"),
  stringsAsFactors = FALSE
)

sub_dmis <- BuildDMI(dat, model)

ggdmcModel documentation built on Aug. 8, 2025, 7:50 p.m.