Line data    Source code

       1          22 : function adjacencymatrix(mesh::Mesh; one = 1, boundary=true)
       2          22 :     i = Vector{Int}(undef, nh(mesh))
       3          22 :     j = Vector{Int}(undef, nh(mesh))
       4          11 :     n = 0
       5             : 
       6          22 :     for e in edges(mesh)
       7         132 :         h = halfedge(e, 1)
       8             : 
       9         168 :         if boundary || !isboundary(mesh, e)
      10         114 :             vi = Int.(vertices(mesh, e))
      11             : 
      12         114 :             i[n+1], i[n+2] = vi
      13         114 :             j[n+2], j[n+1] = vi
      14             : 
      15         114 :             n += 2
      16             :         else
      17          18 :             @massert isboundary(mesh, e)
      18          18 :             h = halfedge(e, 1)
      19          36 :             isboundary(mesh, h) || (h = halfedge(e, 2))
      20             : 
      21          18 :             vi = Int.(vertices(mesh, h))
      22             : 
      23          18 :             i[n+1], j[n+1] = vi
      24             : 
      25          18 :             n += 1
      26             :         end
      27         253 :     end
      28             : 
      29          11 :     resize!(i, n)
      30          11 :     resize!(j, n)
      31             : 
      32          11 :     sparse(i, j, one, nv(mesh), nv(mesh))
      33             : end
      34             : 
      35             : """
      36             :     A = adjacencymatrix(mesh[; one=1, boundary=true])
      37             : 
      38             : Get *sparse* adjacency matrix with `A[i, j] == one` if
      39             : [`halfedge`](@ref) `(i, j)` exists **and** either `boundary==true` or
      40             : `(i, j)` is not a boundary half-edge.
      41             : 
      42             : - `A` has [`nv`](@ref) rows and columns.
      43             : - The optional argument `one` determines the type of
      44             :   `A::SparseMatrix{typof(one)}`.
      45             : - If `boundary==true`, `A` is *always symmetric*. If `boundary==false`,
      46             :   `A` is *symmetric* only if `mesh` has no boundary.
      47             : 
      48             : !!! note
      49             :     Use the optional `boundary` argument to mimic construction of an
      50             :     adjacency matrix from, e.g., a [`facetable`](@ref)
      51             : 
      52             : See also [`graphlaplacian`](@ref)
      53             :     """ adjacencymatrix