Version 9 - delete edge from Delaunay Graph

Question

I have a problem with subgraph in Mathematica 9. In Ver10 the below code works :

(****************************************************)
dist = 1.1;(*when the distance is grather then dist edge is deleted*) 
a = {0, 1, 2 I}; 
coordReal = {Re@#, Im@#} & /@ a;
N=Length[a]; 
planar = DelaunayMesh[coordReal]["AdjacencyMatrix"]; 
Do[
   Do[If ABS{[a[[j]]-a[[i]]] > dist, 
      planar[[j, i]] = 0],
   {i,1,N}],
{j,1,N}]; 
GraphPlot[planar, VertexLabeling -> False,   VertexCoordinateRules -> coord]
(**************************************************)

Is a way to use this method in Mathematica Ver9?

Answer 1

It helps to use proper syntax. For example, N is a built-in symbol and cannot be overwritten. Moreover, it is Abs not ABS and all kinds of bracketing have to match. The following seems to work.

dist = 1.1;
a = {0, 1, 2 I};
coordReal = {Re@#, Im@#} & /@ a;
n = Length[a];
planar = DelaunayMesh[coordReal]["AdjacencyMatrix"];
Do[
  If[Abs[a[[j]] - a[[i]]] > dist, planar[[j, i]] = 0],
  {i, 1, n}, {j, 1, n}];
GraphPlot[planar, VertexLabeling -> False, VertexCoordinateRules -> coordReal]

Edit

In version 9, the issue is that MeshRegion and DelaunayMesh are absent because they were only introduced in version 10.0. The now superseded package "ComputationalGeometry" provides a functionDelaunayTriangulation` that returns the vertex adjacency list of the Delaunay triangulation. From this, the adjacency matrix can be built as follows.

Needs["ComputationalGeometry`"];
planar = SparseArray[Join @@ Thread /@ DelaunayTriangulation[coordReal] -> 1];

The rest should work. Notice however that GraphPlot has also been updated with version 10; since I am running version 11.3, I cannot test it.