flex_prms: Flex_Prms

In dRiftDM: Estimating (Time-Dependent) Drift Diffusion Models

Flex_Prms

Description

Functions for creating, accessing replacing, or printing a flex_prms object. Any object of type flex_prms provides a user-friendly way to specify dependencies, parameter values etc. for a model.

Usage

flex_prms(object, ...) <- value

## S3 replacement method for class 'drift_dm'
flex_prms(object, ..., eval_model = FALSE) <- value

flex_prms(object, ...)

## S3 method for class 'numeric'
flex_prms(object, ..., conds, instr = NULL, messaging = NULL)

## S3 method for class 'flex_prms'
flex_prms(object, ...)

## S3 method for class 'drift_dm'
flex_prms(object, ...)

## S3 method for class 'flex_prms'
print(
  x,
  ...,
  round_digits = drift_dm_default_rounding(),
  dependencies = TRUE,
  cust_parameters = TRUE
)

Arguments

object	an R object (see Details)
...	additional arguments passed on to the specific method.
value	an object of type flex_prms.
eval_model	logical, indicating if the model should be re-evaluated or not when replacing the flex_prms object (see re_evaluate_model).
conds	A character vector, giving the names of the model's conditions. values within conds will be used when addressing the data and when deriving the model's predictions.
instr	optional string with "instructions", see modify_flex_prms().
messaging	optional logical, indicates if messages shall be displayed when processing instr.
x	an object of type flex_prms
round_digits	integer, controls the number of digits shown when printing out a flex_prms object. Default is 3.
dependencies	logical, controlling if a summary of the special dependencies shall be printed.
cust_parameters	logical, controlling if a summary of the custom parameters shall be printed.

Details

Objects of type flex_prms can be modified using the generic modify_flex_prms() function and a corresponding set of "instructions" (see the respective function for more details).

flex_prms() is a generic function. If called with a named numeric vector, then this will create an object of type flex_prms (requires conds to be specified). If called with other data types, gives the respective flex_prms object

⁠flex_prms<-()⁠ is a generic replacement function. Currently this only supports objects of type drift_dm. It will replace/update the model with a new instance of type flex_prms.

Value

The specific value returned depends on which method is called

Creating an object of type flex_prms

Can be achieved by calling flex_prms() with a named numeric vector, thus when calling the underlying method flex_prms.numeric (see the example below). In this case a list with the class label "flex_prms" is returned. It containts three entries:

• A nested list internal_list. This list specifies the dependencies and restrains enforced upon the parameters across conditions. Integers >= 1 indicate that this parameter will be estimated for a specific condition, and conditions with the same number refer to a single parameter. Integers == 0 indicate thtat this parameter will not be esitmated for a specific condition (i.e., it is considered "fixed"). Expressions will be evaluated at run time and specify special dependencies among parameters.

• A nested list linear_internal_list. This list essentially contains the same information as internal_list, but the parameters are sorted so that they can be mapped to an integer vector (relevant only in the depths of the package for the minimization routines).

• A numeric matrix prms_matrix which contains the currently set values for each parameter across all conditions. Per default, the values of each parameter are set equal across all conditions. Additionally, each parameter is assumed to be restrained as equal across all conditions. The values for all parameters given a condition will be passed to the component functions (see comp_funs).

• (optional) A list of additional parameters cust_prms that are derived from the parameters in prms_matrix.

Accessing an object of type flex_prms

Users can access/get the flex_prms object when calling flex_prms() with an object of type drift_dm, fits_ids_dm (see estimate_model_ids()), or flex_prms. In this case, the stored flex_prms object is returned.

Replacing an object of type flex_prms

The flex_prms object stored within an object of type drift_dm can be replaced by calling the generic ⁠flex_prms<-⁠ replacement function. In this case, the modified drift_dm object is returned.

Printing an object of type flex_prms

The print.flex_prms() method invisibly returns the supplied flex_prms object.

Note

There is only a replacement function for drift_dm objects. This is because replacing the solver settings after the model has been fitted (i.e., for a fits_ids_dm object) doesn't make sense.

See Also

estimate_model_ids(), drift_dm(), summary.flex_prms(), modify_flex_prms()

Examples

# Create a flex_prms object -----------------------------------------------
conds <- c("one", "two")
prms <- c(muc = 3, b = 0.5)
one_instr <- "muc ~ one + two"
flex_prms_obj <- flex_prms(
  prms,
  conds = conds,
  instr = one_instr
)
print(flex_prms_obj)


# Access a flex_prms object of a model ------------------------------------
my_model <- ratcliff_dm() # the Ratcliff DDM comes with dRiftDM
print(flex_prms(my_model))


# Replace the flex_prms object of a model ---------------------------------
# create a new flex_prms object
conds <- c("one", "two")
prms <- c(muc = 3, b = 0.6, non_dec = 0.3)
new_flex_prms_obj <- flex_prms(
  prms,
  conds = conds
)

flex_prms(my_model) <- new_flex_prms_obj

# acess the new flex_prms object
print(flex_prms(my_model))


# Control the print method -------------------------------------------------
dmc_model <- dmc_dm() # another, more complex, model; comes with dRiftDM
print(flex_prms(dmc_model), round_digits = 1, cust_parameters = FALSE)

dRiftDM documentation built on April 3, 2025, 7:48 p.m.