Lookup by Matching Values in Multiple Columns

Usage

multiColumnLookup(data, lookup, value = NULL, drop = TRUE, includeKeys = FALSE)

Arguments

data: data frame for which to lookup values in the lookup table
lookup: lookup table defining the key values to be matched against the values in the corresponding columns in data and the corresponding lookup values that are to be returned
value: name of column(s) in lookup containing the value(s) to be looked up. Default: name of the last column in lookup
drop: logical indicating whether or not to return a vector instead of a one-column data frame in case that there is only one value column. The default is TRUE
includeKeys: logical indicating whether or not to include the key column(s) in the returned data frame (for more than one value column or drop = FALSE). The default is FALSE

Value

If value is of length one and drop = TRUE) a vector with as many elements as there are rows in data is returned. Otherwise a data frame with as many rows as there are rows in data

and with the columns named in value is returned.

Examples

(persons <- rbind(
  noFactorDataFrame(name = "Peter", city = "Berlin"),
  noFactorDataFrame(name = "Paul", city = "Paris"),
  noFactorDataFrame(name = "Mary", city = "Berlin"),
  noFactorDataFrame(name = "Paul", city = "Berlin"),
  noFactorDataFrame(name = "Peter", city = "Paris")
))
#>    name   city
#> 1 Peter Berlin
#> 2  Paul  Paris
#> 3  Mary Berlin
#> 4  Paul Berlin
#> 5 Peter  Paris

# Who is cool, which city is cool and which combination is coolest?
(is_cool <- kwb.utils::safeRowBindAll(list(
  noFactorDataFrame(name = "Paul", city = "Berlin", value = "astro-cool"),
  noFactorDataFrame(city = "Berlin", value = "cool"),
  noFactorDataFrame(name = "Paul", value = "mega-cool"),
  noFactorDataFrame(city = "Paris", value = "ca va")
)))
#>   name   city      value
#> 1 Paul Berlin astro-cool
#> 2 <NA> Berlin       cool
#> 3 Paul   <NA>  mega-cool
#> 4 <NA>  Paris      ca va

# Lookup the coolness based on name and city
coolness <- multiColumnLookup(persons, is_cool, value = "value")

# Add the coolness column
cbind(persons, coolness)
#>    name   city   coolness
#> 1 Peter Berlin       cool
#> 2  Paul  Paris  mega-cool
#> 3  Mary Berlin       cool
#> 4  Paul Berlin astro-cool
#> 5 Peter  Paris      ca va