Add differential operator

Project.toml

@@ -11,6 +11,7 @@ Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
 DifferentiationInterface = "a0c0ee7d-e4b9-4e03-894e-1c5f64a51d63"
 DispatchDoctor = "8d63f2c5-f18a-4cf2-ba9d-b3f60fc568c8"
 Distributed = "8ba89e20-285c-5b6f-9357-94700520ee1b"
+DynamicDiff = "7317a516-7a03-4707-b902-c6dba1468ba0"
 DynamicExpressions = "a40a106e-89c9-4ca8-8020-a735e8728b6b"
 DynamicQuantities = "06fc5a27-2a28-4c7c-a15d-362465fb6821"
 LineSearches = "d3d80556-e9d4-5f37-9878-2ab0fcc64255"
@@ -48,6 +49,7 @@ Dates = "1"
 DifferentiationInterface = "0.5, 0.6"
 DispatchDoctor = "^0.4.17"
 Distributed = "<0.0.1, 1"
+DynamicDiff = "0.2"
 DynamicExpressions = "~1.8"
 DynamicQuantities = "1"
 Enzyme = "0.12, 0.13"

src/SymbolicRegression.jl

@@ -131,8 +131,6 @@ using DynamicExpressions:
     with_contents,
     with_metadata
 using DynamicExpressions: with_type_parameters
-# TODO: Reexport D once DynamicAutodiff is registered
-# @reexport using DynamicAutodiff: D
 @reexport using LossFunctions:
     MarginLoss,
     DistanceLoss,
@@ -160,6 +158,7 @@ using DynamicExpressions: with_type_parameters
     LogitDistLoss,
     QuantileLoss,
     LogCoshLoss
+using DynamicDiff: D
 using Compat: @compat, Fix
 
 #! format: off

src/TemplateExpression.jl

@@ -2,6 +2,7 @@ module TemplateExpressionModule
 
 using Random: AbstractRNG
 using Compat: Fix
+using DynamicDiff: DynamicDiff
 using DispatchDoctor: @unstable, @stable
 using StyledStrings: @styled_str, annotatedstring
 using DynamicExpressions:
@@ -39,9 +40,6 @@ using ..MutateModule: MutateModule as MM
 using ..PopMemberModule: PopMember
 using ..ComposableExpressionModule: ComposableExpression, ValidVector
 
-# TODO: Modify `D` once DynamicAutodiff is registered
-# import DynamicAutodiff: D
-
 """
     TemplateStructure{K,E,NF} <: Function
 
@@ -94,10 +92,9 @@ struct ArgumentRecorder{F} <: Function
 end
 (f::ArgumentRecorder)(args...) = f.f(args...)
 
-# TODO: Modify `D` once DynamicAutodiff is registered
 # We pass through the derivative operators, since
 # we just want to record the number of arguments.
-# DA.D(f::ArgumentRecorder, _::Integer) = f
+DynamicDiff.D(f::ArgumentRecorder, ::Integer) = f
 
 """Infers number of features used by each subexpression, by passing in test data."""
 function infer_variable_constraints(::Val{K}, combiner::F) where {K,F}

test/test_composable_expression.jl

@@ -318,3 +318,25 @@ end
     expr = TemplateExpression((; f=c1, g=x1 + x2); structure, operators, variable_names)
     @test expr(X) ≈ [6.0]  # 3 + (1 + 2)
 end
+
+@testitem "Test TemplateExpression with differential operator" tags = [:part3] begin
+    using SymbolicRegression
+    using SymbolicRegression: D
+    using DynamicExpressions: OperatorEnum
+
+    operators = OperatorEnum(; binary_operators=(+, -, *, /), unary_operators=(sin, cos))
+    variable_names = ["x1", "x2"]
+    x1 = ComposableExpression(Node{Float64}(; feature=1); operators, variable_names)
+    x2 = ComposableExpression(Node{Float64}(; feature=2); operators, variable_names)
+    x3 = ComposableExpression(Node{Float64}(; feature=3); operators, variable_names)
+
+    structure = TemplateStructure{(:f, :g)}(
+        ((; f, g), (x1, x2, x3)) -> f(x1) + D(g, 1)(x2, x3)
+    )
+    expr = TemplateExpression(
+        (; f=x1, g=cos(x1 - x2) + 2.5 * x1); structure, operators, variable_names
+    )
+    # Truth: x1 - sin(x2 - x3) + 2.5
+    X = stack(([1.0, 2.0], [3.0, 4.0], [5.0, 6.0]); dims=1)
+    @test expr(X) ≈ [1.0, 2.0] .- sin.([3.0, 4.0] .- [5.0, 6.0]) .+ 2.5
+end