order_expr: Make a order_expr node.

In WinVector/rquery: Relational Query Generator for Data Manipulation at Scale

Make a order_expr node.

Description

order_expr() uses bquote() .()-style escaping.

Usage

order_expr(source, expr, env = parent.frame())

order_expr_nse(source, expr, env = parent.frame())

Arguments

source	source to select from.
expr	expression to order_expr.
env	environment to look to.

Value

select columns node.

Examples

if (requireNamespace("DBI", quietly = TRUE) && requireNamespace("RSQLite", quietly = TRUE)) {
  my_db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
  d <- rq_copy_to(my_db, 'd',
                   data.frame(AUC = 0.6, R2 = 0.2, z = 3))
  TARGETCOL = as.name("AUC")
  optree <- order_expr(d, .(TARGETCOL)/R2) %.>%
    select_columns(., "R2")
  cat(format(optree))
  sql <- to_sql(optree, my_db)
  cat(sql)
  print(DBI::dbGetQuery(my_db, sql))
  DBI::dbDisconnect(my_db)
}

WinVector/rquery documentation built on Aug. 24, 2023, 11:12 a.m.