Find model formula
Returns the formula(s) for the different parts of a model
(like fixed or random effects, zero-inflated component, ...).
formula_ok()
checks if a model formula has valid syntax
regarding writing TRUE
instead of T
inside poly()
and that no data names are used (i.e. no data$variable
, but rather
variable
).
find_formula(x, verbose = TRUE, ...) formula_ok(x, verbose = TRUE, ...)
x |
A fitted model. |
verbose |
Toggle warnings. |
... |
Currently not used. |
A list of formulas that describe the model. For simple models,
only one list-element, conditional
, is returned. For more complex
models, the returned list may have following elements:
conditional
, the "fixed effects" part from the model. One exception are DirichletRegModel
models from DirichletReg, which has two or three components, depending on model
.
random
, the "random effects" part from the model (or the id
for gee-models and similar)
zero_inflated
, the "fixed effects" part from the zero-inflation component of the model
zero_inflated_random
, the "random effects" part from the zero-inflation component of the model
dispersion
, the dispersion formula
instruments
, for fixed-effects regressions like ivreg::ivreg()
, lfe::felm()
or plm::plm()
, the instrumental variables
cluster
, for fixed-effects regressions like lfe::felm()
, the cluster specification
correlation
, for models with correlation-component like nlme::gls()
, the formula that describes the correlation structure
slopes
, for fixed-effects individual-slope models like feisr::feis()
, the formula for the slope parameters
precision
, for DirichletRegModel
models from DirichletReg, when parametrization (i.e. model
) is "alternative"
.
For models of class lme
or gls
the correlation-component
is only returned, when it is explicitly defined as named argument
(form
), e.g. corAR1(form = ~1 | Mare)
data(mtcars) m <- lm(mpg ~ wt + cyl + vs, data = mtcars) find_formula(m) if (require("lme4")) { m <- lmer(Sepal.Length ~ Sepal.Width + (1 | Species), data = iris) f <- find_formula(m) f format(f) }
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