table.express (version 0.1.1)

ExprBuilder: Frame expression builder

Description

Build an expression that will be used inside a data.table::data.table's frame.

Usage

ExprBuilder

Format

An object of class R6ClassGenerator of length 24.

Fields

appends

Extra expressions that go at the end.

expr

The final expression that can be evaluated with base::eval() or rlang::eval_bare().

Methods

initialize(DT)

Constructor that receives a data.table::data.table in DT.

set_select(value, chain_if_needed)

Set the select clause expression(s), starting a new frame if the current one already has said expression set.

set_where(value, chain_if_needed)

Like set_select but for the where clause.

set_by(value)

Set the by clause expression.

chain()

Start a new expression with the current one as its parent.

eval(parent_env, by_ref, ...)

Evaluate the final expression with parent_env as the enclosing environment. If by_ref = FALSE, data.table::copy() is called before. The ellipsis' contents are assigned to the expression's evaluation environment.

print(...)

Prints the built expr.