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Arrow scalars

Source: R/scalar.R
Scalar-class.Rd

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
#> list<item: double>[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"