fix: vertices can be initialized at same position

Author: hexaeder

src/sfdp.jl

@@ -101,6 +101,12 @@ function Base.iterate(iter::LayoutIterator{<:SFDP}, state)
                                ((locs[j] .- locs[i]) / norm(locs[j] .- locs[i])))
             end
         end
+        if any(isnan, force)
+            # if two points are at the exact same location
+            # use random force in any direction
+            rng = MersenneTwister(algo.seed + i)
+            force = randn(rng, Ftype)
+        end
         mask = (!).(pin[i]) # where pin=true mask will multiply with 0
         locs[i] = locs[i] .+ (step .* (force ./ norm(force))) .* mask
         energy = energy + norm(force)^2

src/spring.jl

@@ -104,7 +104,15 @@ function Base.iterate(iter::LayoutIterator{<:Spring}, state)
             #  / |          cos θ = d_x/d = fx/F
             # /---          -> fx = F*d_x/d
             # dx fx
-            force_vec += Ftype(F_d .* (locs[j] .- locs[i]))
+            if !iszero(d)
+                force_vec += Ftype(F_d .* (locs[j] .- locs[i]))
+            else
+                # if two points are at the exact same location
+                # use random force in any direction
+                rng = MersenneTwister(algo.seed + i)
+                force_vec += randn(rng, Ftype)
+            end
+
         end
         force[i] = force_vec
     end