multiColumnLookup: Lookup by Matching Values in Multiple Columns

In KWB-R/kwb.utils: General Utility Functions Developed at KWB

Lookup by Matching Values in Multiple Columns

Description

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")
))

# 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")
)))

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

# Add the coolness column
cbind(persons, coolness)

KWB-R/kwb.utils documentation built on April 1, 2024, 7:12 a.m.