vectra (version 0.6.2)

vtr_schema: Create a star schema over linked vectra tables

Description

Registers a fact table with named dimension links. The schema enables lookup() to resolve columns from dimension tables without writing explicit joins.

Usage

vtr_schema(fact, ...)

Value

A vectra_schema object.

Arguments

fact

A vectra_node object (the central fact table). Must be file-backed (created via tbl(), tbl_csv(), or tbl_sqlite()).

...

Named vectra_link objects created by link(). Names become the dimension aliases used in lookup() (e.g., species$name).

Examples

# \donttest{
f_obs <- tempfile(fileext = ".vtr")
f_sp  <- tempfile(fileext = ".vtr")
f_ct  <- tempfile(fileext = ".vtr")
write_vtr(data.frame(sp_id = 1:3, ct_code = c("AT", "DE", "FR"),
                      value = 10:12), f_obs)
write_vtr(data.frame(sp_id = 1:3,
                      name = c("Oak", "Beech", "Pine")), f_sp)
write_vtr(data.frame(ct_code = c("AT", "DE", "FR"),
                      gdp = c(400, 3800, 2700)), f_ct)

s <- vtr_schema(
  fact    = tbl(f_obs),
  species = link("sp_id", tbl(f_sp)),
  country = link("ct_code", tbl(f_ct))
)
print(s)
unlink(c(f_obs, f_sp, f_ct))
# }