add_vars: Add Variables to Knowledge

In causalDisco: Tools for Causal Discovery on Observational Data

Add Variables to Knowledge

Description

Adds variables to the Knowledge object. If the object is frozen, an error is thrown if any of the variables are not present in the data frame provided to the object.

Usage

add_vars(kn, vars)

Arguments

kn	A Knowledge object.
vars	A character vector of variable names to add.

Value

The updated Knowledge object.

See Also

Other knowledge functions: +.Knowledge(), add_exogenous(), add_tier(), add_to_tier(), as_bnlearn_knowledge(), as_pcalg_constraints(), as_tetrad_knowledge(), convert_tiers_to_forbidden(), deparse_knowledge(), forbid_edge(), get_tiers(), knowledge(), knowledge_to_caugi(), remove_edge(), remove_tiers(), remove_vars(), reorder_tiers(), reposition_tier(), require_edge(), seq_tiers(), unfreeze()

Examples

data(tpc_example)

# create Knowledge object using verbs
kn1 <- knowledge() |>
  add_vars(names(tpc_example)) |>
  add_tier(child) |>
  add_tier(old, after = child) |>
  add_tier(youth, before = old) |>
  add_to_tier(child ~ starts_with("child")) |>
  add_to_tier(youth ~ starts_with("youth")) |>
  add_to_tier(old ~ starts_with("oldage")) |>
  require_edge(child_x1 ~ youth_x3) |>
  forbid_edge(child_x2 ~ youth_x4) |>
  add_exogenous(child_x1) # synonym: add_exo()

# set kn1 to frozen
# (meaning you cannot add variables to the Knowledge object anymore)
# this is to get a true on the identical check
kn1$frozen <- TRUE

# create identical Knowledge object using DSL
kn2 <- knowledge(
  tpc_example,
  tier(
    child ~ starts_with("child"),
    youth ~ starts_with("youth"),
    old ~ starts_with("oldage")
  ),
  child_x1 %-->% youth_x3,
  child_x2 %!-->% youth_x4,
  exo(child_x1) # synonym: exogenous()
)

print(identical(kn1, kn2))

# cannot require an edge against tier direction
try(
  kn1 |> require_edge(oldage_x6 ~ child_x1)
)

# cannot forbid and require same edge
try(
  kn1 |> forbid_edge(child_x1 ~ youth_x3)
)

causalDisco documentation built on April 13, 2026, 5:06 p.m.