lookup (version 1.1)

vlookup: Lookup items in key-value dataframe similar to Excel's vlookup function

Description

This is a simple wrapper to the match function.

Usage

vlookup(x, data, key = "key", value = "value", nomatch = NA)

Value

A vector the same length as x, but containing the values of value. If x[i] is equal to key[j], then the value returned in the ith position of the vector is value[j]. If no match is found, NA is returned.

Arguments

x

Vector of items to lookup in key-value pairs.

data

Dataframe containing key-value columns.

key

Vector of keys that are searched.

value

Vector of values to be returned.

nomatch

The value to be returned in the case when no match is found. Note that it is coerced to integer.

Author

Kevin Wright

Details

Search for elements of x in dataframe data, column key, and return the corresponding element of column value. If no match is found, return nomatch.

Examples

# Example 1.  A and B have different factor levels
A <- factor(c("A","E","F"))
dat <- data.frame(trt = factor(c("E","F","G")),
                  val = c(4,2,0))
vlookup(A,dat, "trt", "val")