Refactor Scale (#140)

* Refactor Scale

* Update Scale tests

* Fix tests and code style

* Make low and high more generic

Author: eliascarv

src/transforms/scale.jl

@@ -35,18 +35,18 @@ Scale(r"[ace]", low=0.3, high=0.7)
 
 * The `low` and `high` values are restricted to the interval [0, 1].
 """
-struct Scale{S<:ColSpec,T<:Real} <: ColwiseFeatureTransform
+struct Scale{S<:ColSpec,T} <: ColwiseFeatureTransform
   colspec::S
   low::T
   high::T
 
-  function Scale(colspec::S, low::T, high::T) where {S<:ColSpec,T<:Real}
+  function Scale(colspec::S, low::T, high::T) where {S<:ColSpec,T}
     @assert 0 ≤ low ≤ high ≤ 1 "invalid quantiles"
     new{S,T}(colspec, low, high)
   end
 end
 
-Scale(colspec::ColSpec, low::Real, high::Real) = 
+Scale(colspec::ColSpec, low, high) = 
   Scale(colspec, promote(low, high)...)
 
 Scale(; low=0.25, high=0.75) = Scale(AllSpec(), low, high)
@@ -59,10 +59,11 @@ assertions(::Type{<:Scale}) = [assert_continuous]
 isrevertible(::Type{<:Scale}) = true
 
 function colcache(transform::Scale, x)
-  levels = (transform.low, transform.high)
-  xl, xh = quantile(x, levels)
+  low = convert(eltype(x), transform.low)
+  high = convert(eltype(x), transform.high)
+  xl, xh = quantile(x, (low, high))
   xl == xh && ((xl, xh) = (zero(xl), one(xh)))
-  (xl=xl, xh=xh)
+  (; xl, xh)
 end
 
 colapply(::Scale, x, c)  = @. (x - c.xl) / (c.xh - c.xl)

test/transforms/scale.jl

@@ -42,7 +42,7 @@
   # columntype does not change
   for FT in (Float16, Float32)
     t = Table(; x=rand(FT, 10))
-    for T in (MinMax(), Scale(low=FT(0), high=FT(0.5)))
+    for T in (MinMax(), Interquartile(), Scale(low=0, high=0.5))
       n, c = apply(T, t)
       @test Tables.columntype(t, :x) == Tables.columntype(n, :x)
       tₒ = revert(T, n, c)