map_fields_q: Map field values from one column into new derived columns...

In WinVector/cdata: Fluid Data Transformations

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

Description

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

Usage

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)
}

WinVector/cdata documentation built on Aug. 29, 2023, 3:56 a.m.