Add split_catenation!

src/other.jl

@@ -74,5 +74,21 @@ function PeriodicGraphs.make_supercell(pge::PeriodicGraphEmbedding, t)
             newpos[n*k+i] = newpos[i] .+ pos .// t
         end
     end
-    return PeriodicGraphEmbedding(g, newpos, cell)
+    PeriodicGraphEmbedding(g, newpos, cell)
+end
+
+function PeriodicGraphs.split_catenation(pge::PeriodicGraphEmbedding{D,T}) where {D,T}
+    pge.cell.hall == 1 || error("Skew a non-P1 cell is not implemented")
+    splits = split_catenation(pge.g)
+    ret = Vector{Tuple{PeriodicGraphEmbedding{D,T}, Vector{PeriodicGraphs.OffsetVertexIterator{D}}, SMatrix{D,D,Int,D*D}, Int}}(undef, length(splits))
+    for (i, (subgraph, vmaps, mat, dim)) in enumerate(splits)
+        newcell = Cell(mat * pge.cell.mat)
+        invmat = inv(Rational{Int}.(mat))
+        newpos = [invmat * pge[x] for x in first(vmaps)]
+        moffsets = [.-floor.(Int, pos) for pos in newpos]
+        subpge = PeriodicGraphEmbedding(copy(subgraph), newpos, newcell)
+        offset_representatives!(subpge, moffsets)
+        ret[i] = (subpge, vmaps, mat, dim)
+    end
+    ret
 end