Execute an rquery pipeline with data.table sources.

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

ex_data_table_step(
  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.

Value

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

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

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))
#> mk_td("a", c(
#>   "x",
#>   "y",
#>   "z")) %.>%
#>  select_columns(., 
#>     c('x', 'y')) %.>%
#>  select_rows(.,
#>    x < 2 & y < 30)
  ex_data_table_step(optree)
#>    x  y
#> 1: 1 20

  # other ways to execute the pipeline include
  ex_data_table(optree)
#>   x  y
#> 1 1 20
  data.frame(x = 0, y = 4, z = 400) %.>% optree
#>   x y
#> 1 0 4