Fix 4-element pair mapping (#596)

- **Fix `mapping` with 4-element pair**
- **add changelog**
- **bump patch version**

Author: jkrumbiegel

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## v0.9.2 - 2025-02-03
+
+- Fixed `data(...) * mapping(col => func => label => scale)` label-extraction bug [#596](https://github.com/MakieOrg/AlgebraOfGraphics.jl/pull/596).
+
 ## v0.9.1 - 2025-01-31
 
 - Fixed passing `axis` keyword to `draw(::Pagination, ...)` [#595](https://github.com/MakieOrg/AlgebraOfGraphics.jl/pull/595).

Project.toml

@@ -1,7 +1,7 @@
 name = "AlgebraOfGraphics"
 uuid = "cbdf2221-f076-402e-a563-3d30da359d67"
 authors = ["Pietro Vertechi", "Julius Krumbiegel"]
-version = "0.9.1"
+version = "0.9.2"
 
 [deps]
 Accessors = "7d9f7c33-5ae7-4f3b-8dc6-eff91059b697"

src/algebra/select.jl

@@ -100,6 +100,12 @@ function select(data, x::Pair{<:Any, <:Pair{<:Any, ScaleID}})
     return vs => transf => label => x[2][2]
 end
 
+function select(data, x::Pair{<:Any, <:Pair{<:Any, <:Pair{<:Any, ScaleID}}})
+    (col, (f, (lbl, id))) = x
+    (vs, (transf, (label, _))) = select(data, col => f => lbl)
+    return vs => transf => label => id
+end
+
 function select(data, x::Pair{<:Any, ScaleID})
     (vs, (transf, (label, _))) = select(data, x[1])
     return vs => transf => label => x[2]

test/algebra.jl

@@ -41,6 +41,12 @@ end
     @test processedlayer.primary[:color] == fill(["x", "x", "x"])
     @test processedlayer.scale_mapping[:color] == :otherscale
 
+    layer = data(df) * mapping(:x => sqrt => "sqrt(X)" => scale(:X2))
+    processedlayer = AlgebraOfGraphics.process_mappings(layer)
+    @test processedlayer.positional[1] == fill(sqrt.(df.x))
+    @test processedlayer.labels[1] == fill("sqrt(X)")
+    @test processedlayer.scale_mapping[1] == :X2
+
     layer = data(df) * mapping(:x, direct(1:1000) => "y")
     processedlayer = AlgebraOfGraphics.process_mappings(layer)
     @test processedlayer.positional[2] == fill(1:1000)