added basic restrict/mask functions and tests (#118)

* added basic restrict/mask functions and tests

* applied feedback

* fixed spaces

* Update restrictions.jl

* update docstring

src/CombinatorialSpaces.jl

@@ -10,6 +10,7 @@ include("DiscreteExteriorCalculus.jl")
 include("MeshInterop.jl")
 include("FastDEC.jl")
 include("Meshes.jl")
+include("restrictions.jl")
 
 @reexport using .SimplicialSets
 @reexport using .DiscreteExteriorCalculus

src/restrictions.jl

@@ -0,0 +1,30 @@
+using CombinatorialSpaces, CombinatorialSpaces.SimplicialSets
+
+export restrict, mask!
+
+"""    restrict(sd::HasDeltaSet, func::Function, form)
+
+restrict a form to a subset of the points.
+
+# Arguments:
+`sd`: the mesh,
+`func`: a function that chooses the submesh indices corresponding to the boundary
+`form`: the vector you want to restrict 
+"""
+restrict(sd::HasDeltaSet, func::Function, form) = form[func(sd)]
+
+restrict(indices, form) = form[indices]
+
+"""    mask(sd::HasDeltaSet, func::Function, form, values)
+
+Masks a form to values on a subset of the points.
+
+# Arguments:
+`sd`: the mesh
+`func`: function that chooses the submesh indices corresponding to the boundary
+`form`: the vector you want to restrict and 
+`values:` is the vector you want to replace with
+"""
+mask!(sd::HasDeltaSet, func::Function, form, values) = setindex!(form, values, func(sd))
+
+mask!(indices, form, values) = setindex!(form, values, indices)

test/restrictions.jl

@@ -0,0 +1,26 @@
+using CombinatorialSpaces
+using GeometryBasics: Point3
+Point3D = Point3{Float64}
+
+rect′ = loadmesh(Rectangle_30x10());
+rect = EmbeddedDeltaDualComplex2D{Bool,Float64,Point3D}(rect′);
+subdivide_duals!(rect, Barycenter());
+
+left_wall_idxs(sd) = begin
+  min_y = minimum(p -> p[2], sd[:point])
+  findall(p -> abs(p[2] - min_y) ≤ sd[1,:length]+1e-4, sd[:point])
+end
+
+# 0-form
+zero_form = 2*ones(nv(rect));
+idxlen = length(left_wall_idxs(rect))
+max = Float64(length(zero_form) + 1)
+
+@test restrict(left_wall_idxs(rect), zero_form) == fill(2.0, idxlen)
+@test restrict(rect, left_wall_idxs, zero_form) == fill(2.0, idxlen)
+
+copy_zero_form = copy(zero_form);
+mask!(rect, left_wall_idxs, copy_zero_form, fill(max, idxlen));
+
+@test copy_zero_form[copy_zero_form .== max] == fill(max, idxlen)
+

test/runtests.jl

@@ -25,4 +25,8 @@ end
   include("Backends.jl")
 end
 
+@testset "Restrictions" begin
+  include("restrictions.jl")
+end
+
 end