LOOKUP: Search, match, and look up values (like Excel's functions...

In bruceR: Broadly Useful Convenient and Efficient R Functions

Search, match, and look up values (like Excel's functions INDEX + MATCH).

Description

In Excel, we can use VLOOKUP, HLOOKUP, XLOOKUP (a new function released in 2019), or the combination of INDEX and MATCH to search, match, and look up values. Here I provide a similar function.

Usage

LOOKUP(
  data,
  vars,
  data.ref,
  vars.ref,
  vars.lookup,
  return = c("new.data", "new.var", "new.value")
)

Arguments

data	Main data.
vars	Character (vector), specifying the variable(s) to be searched in data.
data.ref	Reference data containing both the reference variable(s) and the lookup variable(s).
vars.ref	Character (vector), with the same length and order as vars, specifying the reference variable(s) to be matched in data.ref.
vars.lookup	Character (vector), specifying the variable(s) to be looked up and returned from data.ref.
return	What to return. Default ("new.data") is to return a data frame with the lookup values added. You may also set it to "new.var" or "new.value".

Details

If multiple values were simultaneously matched, a warning message would be printed.

Value

New data object, new variable, or new value (see the argument return).

See Also

dplyr::left_join()

XLOOKUP: Excel University

Examples

ref = data.table(City=rep(c("A", "B", "C"), each=5),
                 Year=rep(2013:2017, times=3),
                 GDP=sample(1000:2000, 15),
                 PM2.5=sample(10:300, 15))
ref

data = data.table(sub=1:5,
                  city=c("A", "A", "B", "C", "C"),
                  year=c(2013, 2014, 2015, 2016, 2017))
data

LOOKUP(data, c("city", "year"), ref, c("City", "Year"), "GDP")
LOOKUP(data, c("city", "year"), ref, c("City", "Year"), c("GDP", "PM2.5"))

bruceR documentation built on June 22, 2024, 12:26 p.m.