match_arrow function

Value matching for Arrow objects

base::match() and base::%in% are not generics, so we can't just define Arrow methods for them. These functions expose the analogous functions in the Arrow C++ library.

match_arrow(x, table, ...)

is_in(x, table, ...)

Arguments

• x: Scalar, Array or ChunkedArray
• table: Scalar, Array,ChunkedArray`, or R vector lookup table.
• ...: additional arguments, ignored

Returns

match_arrow() returns an int32-type Arrow object of the same length and type as x with the (0-based) indexes into table. is_in() returns a boolean-type Arrow object of the same length and type as x with values indicating per element of x it it is present in table.

Examples

# note that the returned value is 0-indexed
cars_tbl <- arrow_table(name = rownames(mtcars), mtcars)
match_arrow(Scalar$create("Mazda RX4 Wag"), cars_tbl$name)

is_in(Array$create("Mazda RX4 Wag"), cars_tbl$name)

# Although there are multiple matches, you are returned the index of the first
# match, as with the base R equivalent
match(4, mtcars$cyl) # 1-indexed
match_arrow(Scalar$create(4), cars_tbl$cyl) # 0-indexed

# If `x` contains multiple values, you are returned the indices of the first
# match for each value.
match(c(4, 6, 8), mtcars$cyl)
match_arrow(Array$create(c(4, 6, 8)), cars_tbl$cyl)

# Return type matches type of `x`
is_in(c(4, 6, 8), mtcars$cyl) # returns vector
is_in(Scalar$create(4), mtcars$cyl) # returns Scalar
is_in(Array$create(c(4, 6, 8)), cars_tbl$cyl) # returns Array
is_in(ChunkedArray$create(c(4, 6), 8), cars_tbl$cyl) # returns ChunkedArray