feat: data interpolations

Manifest.toml

@@ -1,8 +1,8 @@
 # This file is machine-generated - editing it directly is not advised
 
-julia_version = "1.10.3"
+julia_version = "1.10.4"
 manifest_format = "2.0"
-project_hash = "ace2e1df9d9dbcf666fc13e87dfbf3d8881dd7d1"
+project_hash = "1d025dab4c6dd8f7ccf572cc68ecdd4a371d25d2"
 
 [[deps.ADTypes]]
 git-tree-sha1 = "99a6f5d0ce1c7c6afdb759daa30226f71c54f6b0"

Project.toml

@@ -11,6 +11,7 @@ Einsum = "b7d42ee7-0b51-5a75-98ca-779d3107e4c0"
 ExponentialAction = "e24c0720-ea99-47e8-929e-571b494574d3"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 IJulia = "7073ff75-c697-5162-941a-fcdaad2a7d2a"
+Interpolations = "a98d9a8b-a2ab-59e6-89dd-64a1c18fca59"
 Ipopt = "b6b21f68-93f8-5de0-b562-5493be1d77c9"
 JLD2 = "033835bb-8acc-5ee8-8aae-3f567f8a3819"
 Libdl = "8f399da3-3557-5675-b5ff-fb832c97cbdb"

src/QuantumCollocation.jl

@@ -57,6 +57,9 @@ include("rollouts.jl")
 include("trajectory_initialization.jl")
 @reexport using .TrajectoryInitialization
 
+include("trajectory_interpolations.jl")
+@reexport using .TrajectoryInterpolation
+
 include("problem_templates/_problem_templates.jl")
 @reexport using .ProblemTemplates
 

src/trajectory_interpolations.jl

@@ -0,0 +1,119 @@
+module TrajectoryInterpolation
+
+export DataInterpolation
+
+using NamedTrajectories
+
+using Interpolations: Extrapolation, constant_interpolation, linear_interpolation
+using TestItemRunner
+
+
+struct DataInterpolation
+    times::Vector{Float64}
+    values::Matrix{Float64}
+    interpolants::Vector{Extrapolation}
+    timestep_components::Vector{Int}
+    values_components::Vector{Int}
+
+    function DataInterpolation(
+        times::AbstractVector{Float64}, values::AbstractMatrix{Float64}; 
+        timestep_components::AbstractVector{Int}=Int[], kind::Symbol=:linear
+    )   
+        comps = setdiff(1:size(values, 1), timestep_components)
+        if kind == :linear
+            interpolants = [linear_interpolation(times, values[c, :]) for c in comps]
+        elseif kind == :constant
+            interpolants = [constant_interpolation(times, values[c, :]) for c in comps]
+        else
+            error("Unknown interpolation kind: $kind")
+        end
+        return new(times, values, interpolants, timestep_components, comps)
+    end
+
+    function DataInterpolation(
+        T::Int, Δt::Real, values::AbstractMatrix{Float64}; kwargs...
+    )
+        times = range(0, Δt * (T - 1), step=Δt)
+        return DataInterpolation(times, values; kwargs...)
+    end
+
+    function DataInterpolation(
+        traj::NamedTrajectory; timestep_symbol::Symbol=:Δt, kwargs...
+    )
+        if timestep_symbol ∈ keys(traj.components)
+            timestep_components = traj.components[timestep_symbol]
+        else
+            timestep_components = Int[]
+        end
+        return DataInterpolation(
+            get_times(traj), traj.data; timestep_components=timestep_components, kwargs...
+        )
+    end
+end
+
+function (traj_int::DataInterpolation)(times::AbstractVector)
+    values = zeros(eltype(traj_int.values), size(traj_int.values, 1), length(times))
+    for (c, interp) in zip(traj_int.values_components, traj_int.interpolants)
+        values[c, :] = interp(times)
+    end
+    if !isempty(traj_int.timestep_components)
+        timesteps = times[2:end] .- times[1:end-1]
+        # NOTE: Arbitrary choice of the last timestep
+        values[traj_int.timestep_components, :] = vcat(timesteps, timesteps[end])
+    end
+    return values
+end
+
+function (traj_int::DataInterpolation)(T::Int)
+    times = range(traj_int.times[1], traj_int.times[end], length=T)
+    return traj_int(times)
+end
+
+# =========================================================================
+
+@testitem "Trajectory interpolation test" begin
+    include("../test/test_utils.jl")
+
+    # fixed time
+    traj = named_trajectory_type_1()
+
+    interp = DataInterpolation(traj)
+    new_data = interp(get_times(traj))
+    @test new_data ≈ traj.data
+
+    new_data = interp(2 * traj.T)
+    @test size(new_data) == (size(traj.data, 1), 2 * traj.T)
+
+    # free time
+    free_traj = named_trajectory_type_1(free_time=true)
+
+    interp = DataInterpolation(free_traj)
+    new_free_data = interp(get_times(traj))
+
+    # Replace the final timestep with the original value (can't be known a priori) 
+    new_free_data[free_traj.components.Δt, end] = free_traj.data[free_traj.components.Δt, end]
+    @test new_free_data ≈ free_traj.data
+
+    new_free_data = interp(2 * traj.T)
+    @test size(new_free_data) == (size(free_traj.data, 1), 2 * traj.T)
+end
+
+@testitem "Component interpolation test" begin
+    include("../test/test_utils.jl")
+
+    traj = named_trajectory_type_1()
+
+    # interpolate with times
+    interp_val1 = DataInterpolation(get_times(traj), traj.a)
+    @test size(interp_val1(2 * traj.T)) == (size(traj.a, 1), 2 * traj.T)
+
+    # interpolate with steps
+    interp_val2 = DataInterpolation(traj.T, traj.timestep, traj.a)
+    @test size(interp_val2(3 * traj.T)) == (size(traj.a, 1), 3 * traj.T)
+
+    # check if times match
+    @test interp_val1.times ≈ interp_val2.times
+end
+
+
+end

test/test_utils.jl

@@ -1,6 +1,5 @@
-"""
-    utility functions for debugging tests
-"""
+using NamedTrajectories
+
 
 """
     dense(vals, structure, shape)