ex_data_table_step.relop_project {rqdatatable}

Implement projection operator.

Description

data.table based implementation.

Usage

## S3 method for class 'relop_project'
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.

Examples

dL <- build_frame(
  "subjectID", "surveyCategory"     , "assessmentTotal" |
    1          , "withdrawal behavior", 5                 |
    1          , "positive re-framing", 2                 |
    2          , "withdrawal behavior", 3                 |
    2          , "positive re-framing", 4                 )
test_p <- local_td(dL) %.>%
  project(.,
          maxscore := max(assessmentTotal),
          count := n(),
          groupby = 'subjectID')
cat(format(test_p))
dL %.>% test_p