Small fixes

src/recode.jl

@@ -36,22 +36,19 @@ recode!(dest::CategoricalArray, src::AbstractArray, pairs::Pair...) =
 recode!(dest::CategoricalArray, src::CategoricalArray, pairs::Pair...) =
     recode!(dest, src, nothing, pairs...)
 
-
 """
     recode_in(x, collection)
 
 Helper function to test if `x` is a member of `collection`.
 
 The default method is to test if any element in the `collection` `isequal` to
-`x`. For sets using `in` should be faster than the default method.
+`x`. For `Set`s `in` is used as it is faster than the default method and equivalent to it.
 A user defined type could override this method to define an appropriate test function.
 """
 @inline recode_in(x, ::Missing) = false
-@inline recode_in(x, ::AbstractString) = false
 @inline recode_in(x, collection::Set) = x in collection
 @inline recode_in(x, collection) = any(x ≅ y for y in collection)
 
-
 function recode!(dest::AbstractArray{T}, src::AbstractArray, default::Any, pairs::Pair...) where {T}
     if length(dest) != length(src)
         throw(DimensionMismatch("dest and src must be of the same length (got $(length(dest)) and $(length(src)))"))
@@ -63,7 +60,7 @@ function recode!(dest::AbstractArray{T}, src::AbstractArray, default::Any, pairs
         for j in 1:length(pairs)
             p = pairs[j]
             # we use isequal and recode_in because we cannot really distinguish scalars from collections
-            if (x ≅ p.first || recode_in(x, p.first))
+            if x ≅ p.first || recode_in(x, p.first)
                 dest[i] = p.second
                 @goto nextitem
             end
@@ -116,7 +113,7 @@ function recode!(dest::CategoricalArray{T}, src::AbstractArray, default::Any, pa
         for j in 1:length(pairs)
             p = pairs[j]
             # we use isequal and recode_in because we cannot really distinguish scalars from collections
-            if (x ≅ p.first || recode_in(x, p.first))
+            if x ≅ p.first || recode_in(x, p.first)
                 drefs[i] = dupvals ? pairmap[j] : j
                 @goto nextitem
             end
@@ -229,7 +226,7 @@ function recode!(dest::CategoricalArray{T, N, R}, src::CategoricalArray,
     @inbounds for (i, l) in enumerate(srclevels)
         for j in 1:length(pairs)
             p = pairs[j]
-            if (l ≅ p.first || recode_in(l, p.first))
+            if l ≅ p.first || recode_in(l, p.first)
                 levelsmap[i+1] = pairmap[j]
                 @goto nextitem
             end

test/16_recode.jl

@@ -12,6 +12,8 @@ const ≅ = isequal
 @testset "recode_in" begin
     @testset "collection is a string" begin
         @test !CategoricalArrays.recode_in("a", "ab")
+        @test CategoricalArrays.recode_in('a', "ab")
+        @test !CategoricalArrays.recode_in('c', "ab")
         @test !CategoricalArrays.recode_in(missing, "b")
     end
     @testset "collection without missing" begin