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

This is a simple wrapper to the match function.

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

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.

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.

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.

Author

Kevin Wright

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")
#> [1] NA  4  2