Check signs of interactions in force-tuning (#34)

Aimed at preventing silly user errors.

Author: timholy

src/forces.jl

@@ -73,14 +73,25 @@ forcecomponents(seq, interactions::InteractionList, residueindexes=eachindex(seq
     forcecomponents(collectresidues(seq), interactions, residueindexes; kwargs...)
 
 function forcecomponents(mgmms::AbstractVector{<:IsotropicMultiGMM{N}}, interactions::InteractionList, residueindexes=eachindex(mgmms)) where N
-    GaussianMixtureAlignment.validate_interactions(Dict(interactions)) || throw(ArgumentError("interactions must appear in only one order, got $interactions"))
+    interactionsdict = Dict(interactions)
+    GaussianMixtureAlignment.validate_interactions(interactionsdict) || throw(ArgumentError("interactions must appear in only one order, got $interactions"))
     # We don't support (:Ionic, x) where x != :Ionic
     for interaction in interactions
         key1, key2 = getfeatures(interaction)
         if (key1 === :Ionic && key2 !== :Ionic) || (key1 !== :Ionic && key2 === :Ionic)
             throw(ArgumentError("(:Ionic, x) is not supported unless x=:Ionic, got $interaction"))
         end
     end
+    cionic = get(interactionsdict, (:Ionic, :Ionic), nothing)
+    if cionic !== nothing
+        # If (:Ionic, :Ionic) is present, the code below will handle the signs. But we need to ensure consistency with other interactions
+        for (key, sprod) in ((:Steric, :Steric) => 1, (:Hydrophobe, :Hydrophobe) => -1, (:Donor, :Acceptor) => -1)
+            c = get(interactionsdict, key, nothing)
+            if c !== nothing
+                sign(cionic) * sign(c) != sprod && throw(ArgumentError("(:Ionic, :Ionic) is not sign-compatible with $key"))
+            end
+        end
+    end
     forces = [zeros(N, eachindex(interactions)) for _ in residueindexes]
     for (k, interaction) in pairs(interactions)
         key1, key2 = getfeatures(interaction)

test/runtests.jl

@@ -237,6 +237,8 @@ using Test
         w = optimize_weights(forces)
         @test all(>=(0), w)
         @test sum(w) ≈ 1 atol=1e-6
+        badinteractions = [(:Steric, :Steric) => 1, (:Hydrophobe, :Hydrophobe) => -1, (:Ionic, :Ionic) => -1]
+        @test_throws "is not sign-compatible" forcecomponents([mgmmx, mgmmy], badinteractions)
         weighted_interactions = [key => w0*wi for ((key, w0), wi) in zip(interactions, w)]
         wforces = forcecomponents([mgmmx, mgmmy], weighted_interactions)
         @test all(f .* w' ≈ wf for (f, wf) in zip(forces, wforces))