prior_from_spec: Build a 'prior' list for 'tulpa_nested_laplace()' from a...

In tulpa: Templated Unified Library for Posterior Approximation in Bayesian Hierarchical Models

Build a prior list for tulpa_nested_laplace() from a tulpa spec object

Description

Validates a tulpa_temporal or tulpa_spatial specification against data, then converts it to the prior list shape consumed by tulpa_nested_laplace(). Mainly an internal helper for callers that already have a fitted spec; users typically pass spec + data directly to tulpa_nested_laplace() instead.

Supported spec types:

• tulpa_temporal with ⁠type in {"rw1", "rw2", "ar1"}⁠

• tulpa_spatial, areal ⁠type in {"car", "icar", "car_proper", "bym2"}⁠. An areal spec returns the graph fields only – type, spatial_idx, n_spatial_units, adj_row_ptr, adj_col_idx, n_neighbors – plus scale_factor for bym2 and the eigenvalue-derived rho_bounds for proper CAR. No grid field is returned for any areal type: the outer axes are built later by the family's registry defaults() closure, and proper CAR's ⁠(tau, rho)⁠ grid is built there from those bounds.

• tulpa_gp / tulpa_hsgp, continuous ⁠type in {"gp", "nngp", "hsgp"}⁠: validated against data and routed to the nngp / hsgp nested kernel through the shared converter.

SPDE is the one continuous field not built here – it carries its own (range, sigma) FEM integrator; call fit_spde() with the spatial_spde() spec.

Usage

prior_from_spec(spec, data)

Arguments

spec	A tulpa_temporal or tulpa_spatial object.
data	Data frame the spec resolves time/group/site indices against.

Value

A prior list ready for tulpa_nested_laplace().

Examples

d <- data.frame(year = rep(1:10, each = 3))
pr <- prior_from_spec(temporal_ar1("year"), d)
str(pr)

tulpa documentation built on Oct. 19, 2026, 5:09 p.m.