Map field values from one column into new derived columns (query based, takes name of table).

Map field values from one column into new derived columns (query based, takes name of table).

map_fields_q(
  dname,
  cname,
  mname,
  my_db,
  rname,
  ...,
  d_qualifiers = NULL,
  m_qualifiers = NULL
)

Arguments

dname	name of table to re-map.
cname	name of column to re-map.
mname	name of table of data describing the mapping (cname column is source, derived columns are destinations).
my_db	database handle.
rname	name of result table.
...	force later arguments to be by name.
d_qualifiers	optional named ordered vector of strings carrying additional db hierarchy terms, such as schema.
m_qualifiers	optional named ordered vector of strings carrying additional db hierarchy terms, such as schema.

Value

re-mapped table

Examples

if (requireNamespace("DBI", quietly = TRUE) &&
  requireNamespace("RSQLite", quietly = TRUE)) {
  my_db <- DBI::dbConnect(RSQLite::SQLite(),
                          ":memory:")
  DBI::dbWriteTable(
    my_db,
    'd',
    data.frame(what = c("acc", "loss",
                        "val_acc", "val_loss"),
               score = c(0.8, 1.2,
                         0.7, 1.7),
               stringsAsFactors = FALSE),
    overwrite = TRUE,
    temporary = TRUE)
  DBI::dbWriteTable(
    my_db,
    'm',
    data.frame(what = c("acc", "loss",
                        "val_acc", "val_loss"),
               measure = c("accuracy", "log-loss",
                           "accuracy", "log-loss"),
               dataset = c("train", "train", "validation", "validation"),
               stringsAsFactors = FALSE),
    overwrite = TRUE,
    temporary = TRUE)

  map_fields_q('d', 'what', 'm', my_db, "dm")
  cdata::qlook(my_db, 'dm')
  DBI::dbDisconnect(my_db)
}
#> table `dm` SQLiteConnection 
#>  nrow: 4 
#> 'data.frame':	4 obs. of  4 variables:
#>  $ what   : chr  "acc" "loss" "val_acc" "val_loss"
#>  $ score  : num  0.8 1.2 0.7 1.7
#>  $ measure: chr  "accuracy" "log-loss" "accuracy" "log-loss"
#>  $ dataset: chr  "train" "train" "validation" "validation"