make grid coloring not depend on iteration order of dicts and sets

Author: KristofferC

CHANGELOG.md

@@ -32,6 +32,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
    [#1235])
  - Relax vector input type from `Vector` to `AbstractVector` in `evaluate_at_points!`.
    ([#1183])
+- The result of grid coloring is now not dependent on iteration order of dictionaries and sets. This may change the coloring obtained from `create_coloring`
+  compared to previous Ferrite versions.
 
 ### Documentation updates
  - Extended assembly docs with information on how to support direct assembly into new matrix

src/Ferrite.jl

@@ -12,7 +12,7 @@ using LinearAlgebra:
 using NearestNeighbors:
     NearestNeighbors, KDTree, knn
 using OrderedCollections:
-    OrderedSet
+    OrderedDict, OrderedSet
 using SparseArrays:
     SparseArrays, SparseMatrixCSC, nonzeros, nzrange, rowvals,
     AbstractSparseMatrix, AbstractSparseMatrixCSC, sparsevec

src/Grid/coloring.jl

@@ -1,6 +1,6 @@
 # Incidence matrix for element connections in the grid
 function create_incidence_matrix(g::AbstractGrid, cellset = 1:getncells(g))
-    cell_containing_node = Dict{Int, Set{Int}}()
+    cell_containing_node = OrderedDict{Int, Set{Int}}()
     for cellid in cellset
         cell = getcells(g, cellid)
         for v in get_node_ids(cell)
@@ -78,21 +78,21 @@ function workstream_coloring(incidence_matrix, cellset)
     ###################
     # 1. Partitioning #
     ###################
-    zones = Set{Int}[]
+    zones = OrderedSet{Int}[]
     n_visited = 0
     Z = 1
-    Z0 = Set{Int}() # Dummy zone
-    remaining_cells = Set{Int}(cellset)
+    Z0 = OrderedSet{Int}() # Dummy zone
+    remaining_cells = OrderedSet{Int}(cellset)
     while n_visited < length(cellset)
         setdiff!(remaining_cells, zones...)
         ## Zone 1: Just the first element
         @assert length(remaining_cells) > 0
-        push!(zones, Set{Int}(first(remaining_cells)))
+        push!(zones, OrderedSet{Int}((first(remaining_cells),)))
         Z += 1
         n_visited += 1
         ## Zone N: All elements with connection to elements in Zone N-1
         while true
-            s = Set{Int}()
+            s = OrderedSet{Int}()
             # Loop over all elements in previous zone and add their neighbouring elements
             # unless they are in any of the previous 2 zones.
             empty_zone = true

test/test_vtk_export.jl

@@ -21,7 +21,7 @@
                 @test Ferrite.write_cell_colors(vtk, grid, colors) === vtk
             end
             @test v isa VTKGridFile
-            @test bytes2hex(open(SHA.sha1, fname * ".vtu")) == "b804d0b064121b672d8e35bcff8446eda361cac3"
+            @test bytes2hex(open(SHA.sha1, fname * ".vtu")) == "960aa8323da524f642376bba6ff7d8f7c349b218"
         end
     end
     @testset "constraints" begin