Return column names

Source: R/relop.R

Return column names

column_names(x, ...)

Arguments

x

rquery operation tree.
...

generic additional arguments

Value

vector of column names

Examples


if (requireNamespace("DBI", quietly = TRUE) && requireNamespace("RSQLite", quietly = TRUE)) {
  my_db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
  d1 <- rq_copy_to(my_db, 'd1',
                    data.frame(AUC = 0.6, R2 = 0.2))
  d2 <- rq_copy_to(my_db, 'd2',
                    data.frame(AUC = 0.6, D = 0.3))
  optree <- natural_join(d1, d2, by = "AUC")
  cat(format(optree))
  print(column_names(optree))
  DBI::dbDisconnect(my_db)
}

#> mk_td("d1", c(
#>   "AUC",
#>   "R2")) %.>%
#>  natural_join(.,
#>   mk_td("d2", c(
#>     "AUC",
#>     "D")),
#>   jointype = "INNER", by = c('AUC'))
#> [1] "AUC" "R2"  "D"