Working with vtools: Flexible Variable Selection

Søren Højsgaard

library(doBy)
library(rlang)
data(CO2)

Overview

The v* functions in the doBy package allow for flexible and consistent handling of variable input. These tools support unquoted names, character vectors, and formulas.

The main functions are:

• vparse() – extract variable names from flexible input
• v() – shorthand for vparse()
• vselect() – select columns from a data frame using flexible input
• vcheck() – verify that variables exist in a data frame
• vmap() – apply a function to each parsed variable name
• vrename() – rename variables in a data frame

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Examples

vparse()

vparse(Treatment, Type)
vparse(c("Treatment", "Type"))
vparse(~Treatment + Type)

v() – shorthand for vparse()

v(Treatment, Type)
v(~Treatment + Type)
v(c("Treatment", "Type"))

vselect()

vselect(CO2, Treatment, Type)
vselect(CO2, ~Treatment + Type)

vcheck()

vcheck(CO2, Treatment)
vcheck(CO2, ~Treatment + Type)

vmap()

vmap(~Treatment + Type, toupper)

vrename()

vrename(CO2, c(Treatment = "Trt", Type = "Group"))

Summary

The v* tools simplify working with variable names and selection in data frames, making it easier to write functions that accept flexible input formats.