Arrow scalars

A Scalar holds a single value of an Arrow type.

Factory

The Scalar$create() factory method instantiates a Scalar and takes the following arguments:

• x: an R vector, list, or data.frame

• type: an optional data type for x. If omitted, the type will be inferred from the data.

Usage

a <- Scalar$create(x)
length(a)

print(a)
a == a

Methods

• $ToString(): convert to a string

• $as_vector(): convert to an R vector

• $as_array(): convert to an Arrow Array

• $Equals(other): is this Scalar equal to other

• $ApproxEquals(other): is this Scalar approximately equal to other

• $is_valid: is this Scalar valid

• $null_count: number of invalid values - 1 or 0

• $type: Scalar type

• $cast(target_type, safe = TRUE, options = cast_options(safe)): cast value to a different type

Examples

Scalar$create(pi)
#> Scalar
#> 3.141592653589793
Scalar$create(404)
#> Scalar
#> 404
# If you pass a vector into Scalar$create, you get a list containing your items
Scalar$create(c(1, 2, 3))
#> Scalar
#> [
#>   [
#>     1,
#>     2,
#>     3
#>   ]
#> ]

# Comparisons
my_scalar <- Scalar$create(99)
my_scalar$ApproxEquals(Scalar$create(99.00001)) # FALSE
#> [1] FALSE
my_scalar$ApproxEquals(Scalar$create(99.000009)) # TRUE
#> [1] TRUE
my_scalar$Equals(Scalar$create(99.000009)) # FALSE
#> [1] FALSE
my_scalar$Equals(Scalar$create(99L)) # FALSE (types don't match)
#> [1] FALSE

my_scalar$ToString()
#> [1] "99"