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Parse a mixed-model formula

Source: R/formula.R
tulpa_parse_formula.Rd

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)

Arguments

formula

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

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