Define a key for a data frame

Attaches key metadata to a data frame, marking which column(s) form the unique identifier for rows. Keys are validated for uniqueness at creation.

Usage

key(.data, ..., .validate = TRUE, .strict = FALSE)

key(.data) <- value

Arguments

.data

A data frame or tibble.

...

Column names (unquoted) that form the key. Can be a single column or multiple columns for a composite key.

.validate

If TRUE (default), check that the key is unique.

.strict

If TRUE, error on non-unique keys. If FALSE (default), warn but still attach the key.

value

Character vector of column names to use as key.

Value

A keyed data frame (class keyed_df).

Examples

df <- data.frame(id = 1:3, x = c("a", "b", "c"))
key(df, id)

# Composite key
df2 <- data.frame(country = c("US", "US", "UK"), year = c(2020, 2021, 2020), val = 1:3)
key(df2, country, year)