Combine conditional data-generation rules into a specification

Usage

define_conditions(...)

Arguments

...

One of three forms.

Rules. outcome = when(group == 1, normal(mean = 5, sd = 1)) names the variable with the argument name, states the condition that selects the rows the rule writes, and states their distribution as a call. Any distribution in list_distributions() may be used, and its parameters may be expressions over the data. Repeating the argument name gives one variable several rules, which is how a variable takes a different distribution in each group. when(TRUE, ...) applies to every row.

Specification columns given as named vectors (variable, condition, formula, variance, distribution, link).

Objects created by define_condition().

The forms cannot be mixed in one call.

In the column form, variable, condition and formula are required. A column given as a single value is recycled across every rule. variance defaults to 0, distribution to "normal", and link to "identity".

Value

A simulab_condition_spec base data.frame. Rules written with when() give one row per parameter, with columns rule, variable, condition, distribution, parameter and value; the other two forms give one row per rule with the formula/variance columns.

Examples

# Rules. One line per rule; a repeated name gives a variable several rules.
define_conditions(
  outcome = when(group == 1, normal(mean = 5, sd = 1)),
  outcome = when(group == 0, poisson(lambda = 2)),
  bonus   = when(group == 1, gamma(shape = 2, rate = 0.5))
)
#>   rule variable  condition distribution parameter value
#> 1    1  outcome group == 1       normal      mean     5
#> 2    1  outcome group == 1       normal        sd     1
#> 3    2  outcome group == 0      poisson    lambda     2
#> 4    3    bonus group == 1        gamma     shape     2
#> 5    3    bonus group == 1        gamma      rate   0.5

# One call, named arguments, one row per rule.
define_conditions(
  variable  = c("outcome", "outcome"),
  condition = c("group == 1", "group == 0"),
  formula   = c("2", "0"),
  variance  = "1"
)
#>   variable  condition distribution formula variance     link
#> 1  outcome group == 1       normal       2        1 identity
#> 2  outcome group == 0       normal       0        1 identity

# Definitions built one at a time are still accepted.
define_conditions(
  define_condition("outcome", condition = "group == 1",
                   formula = "2", variance = "1", distribution = "normal"),
  define_condition("outcome", condition = "group == 0",
                   formula = "0", variance = "1", distribution = "normal")
)
#>   variable  condition distribution formula variance     link
#> 1  outcome group == 1       normal       2        1 identity
#> 2  outcome group == 0       normal       0        1 identity