tulpa_parse_formula: Parse a mixed-model formula

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

Parse a mixed-model formula

Description

Decomposes a formula into fixed effects and random effects by walking the formula's abstract syntax tree. This is structural recursion with pattern matching on bar terms – no string manipulation.

Usage

tulpa_parse_formula(formula)

## S3 method for class 'tulpa_parsed_formula'
print(x, ...)

Arguments

formula	A formula object (e.g., y ~ x + (1 | group))
x	A tulpa_parsed_formula object.
...	Ignored.

Value

A list with:

• response: character, the response variable label (NULL if none)

• response_expr: language object, the LHS of ~ (NULL if none)

• fixed_formula: formula, the fixed-effects-only formula

• random_effects: list of parsed RE specifications

• n_re_terms: integer, number of RE terms

• latent_blocks: list of evaluated user-defined latent block objects (typically tgmrf S3 objects), one per latent(...) term in the original formula. Empty list when no latent(...) terms are present.

• n_latent_blocks: integer, number of latent(...) terms

• original: the original formula

Examples

pf <- tulpa_parse_formula(y ~ x1 + x2 + (1 | group) + (x1 || site))
pf$response        # "y"
pf$fixed_formula   # y ~ x1 + x2

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