ex_data_table {rqdatatable}

Execute an rquery pipeline with data.table sources.

Description

data.tables are looked for by name in the tables argument and in the execution environment. Main external execution interface.

Usage

ex_data_table(
  optree,
  ...,
  tables = list(),
  source_usage = NULL,
  source_limit = NULL,
  env = parent.frame()
)

Arguments

optree

relop operations tree.

...

not used, force later arguments to bind by name.

tables

named list map from table names used in nodes to data.tables and data.frames.

source_usage

list mapping source table names to vectors of columns used.

source_limit

if not null limit all table sources to no more than this many rows (used for debugging).

env

environment to work in.

Details

• ex_data_table_step.relop_drop_columns: implement drop columns

• ex_data_table_step.relop_extend: implement extend/assign operator

• ex_data_table_step.relop_natural_join: implement natural join

• ex_data_table_step.relop_non_sql: direct function (non-sql) operator (not implemented for data.table)

• ex_data_table_step.relop_null_replace: implement NA/NULL replacement

• ex_data_table_step.relop_orderby: implement row ordering

• ex_data_table_step.relop_project: implement row ordering

• ex_data_table_step.relop_rename_columns: implement column renaming

• ex_data_table_step.relop_select_columns: implement select columns

• ex_data_table_step.relop_select_rows: implement select rows

• ex_data_table_step.relop_sql: direct sql operator (not implemented for data.table)

• ex_data_table_step.relop_table_source: implement data source

• ex_data_table_step.relop_theta_join: implement theta join (not implemented for data.table)

• ex_data_table_step.relop_unionall: implement row binding

Value

resulting data.table (intermediate tables can somtimes be mutated as is practice with data.table).

Examples

  a <- data.table::data.table(x = c(1, 2) , y = c(20, 30), z = c(300, 400))
  optree <- local_td(a) %.>%
     select_columns(., c("x", "y")) %.>%
     select_rows_nse(., x<2 & y<30)
  cat(format(optree))
  ex_data_table(optree)

  # other ways to execute the pipeline include
  data.frame(x = 0, y = 4, z = 400) %.>% optree