Apply conditional generation rules — apply

Rules are evaluated in order, so later rules may intentionally replace values written by earlier rules. A row no rule selects is left missing.

Usage

apply_conditions(data, specification, seed = NULL, envir = parent.frame())

Arguments

data: Input base data.frame.
specification: Rules from define_conditions(), in either the rule form written with when() or the formula/variance column form.
seed: Optional random seed.
envir: Environment used to resolve values a condition or formula names but the data does not carry. Distribution parameters inside when() are evaluated against the data alone, so they may only name columns.

Value

A simulab_sim base data.frame with conditional variables added.

Examples

data <- data.frame(id = 1:100, group = rep(0:1, each = 50))

# Rules written with when() may use any distribution in the catalogue.
result <- apply_conditions(
  data,
  specification = define_conditions(
    outcome = when(group == 1, normal(mean = 5, sd = 1)),
    outcome = when(group == 0, poisson(lambda = 2))
  ),
  seed = 1
)
head(result)
#> <simulab_sim:conditional> 6 rows x 3 columns
#>   id group outcome
#> 1  1     0       2
#> 2  2     0       1
#> 3  3     0       1
#> 4  4     0       6
#> 5  5     0       2
#> 6  6     0       1
#> 
#> Other tables: conditions. Read one with as.data.frame(x, what = "conditions").

specification <- 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")
)
result <- apply_conditions(data, specification = specification, seed = 1)
head(result)
#> <simulab_sim:conditional> 6 rows x 3 columns
#>   id group    outcome
#> 1  1     0  0.3981059
#> 2  2     0 -0.6120264
#> 3  3     0  0.3411197
#> 4  4     0 -1.1293631
#> 5  5     0  1.4330237
#> 6  6     0  1.9803999
#> 
#> Other tables: conditions. Read one with as.data.frame(x, what = "conditions").