I want to create a adjacency list using json object. I would like to implement json object for adjacency list in the following format.
var JSONobj= {node1:[{x1,y1},{x3,y3},{x4,y4}], node2:[{x2,y2},{x3,y3}], node3:[]}
My doubt is, whether I can add values to coordinate list dynamically such as JSONobj.node3[0]={x4,y4}?
or is there any better way to add values to JSONobj from outside the object declaration?
You can push elements into a JSON object since its just a pretty array.
JSONobj.push({"newElement":"value"});
JSONobj.node3.push({"newElement":"value"}); As far as I know that's pretty much it for adding new objects to a JSON array. You could always try JSONobj.node3[0][0] = 'x4' But that will give you something like this JSONobj -> node3 -> 0 -> 0 = 'x4'JSON in Javascript is an ordinary (structured) Javascript object. So, first of all it must adhere to the object syntax. node1, x1, etc, must be defined variables or explicit constants. {x1, x2} is not defined in JS. It must be attribute: value, e.g. {x1: 1, "x2": "a2"}. As soon as you have a syntactically valid object, you can manipulate it as you like. E.g.
var node1 = "node1";
var x1 = "x1";
var y1 = "y1";
var x3 = "x3";
var y3 = "y3";
var JSONobj= {node1: [{x1:1,y1:1}, {x3:2,y3:3}],
"node2": [{"x2":1,"y2":2}], "node3": []};
JSONobj.node3[0] = {"x4":4,"y4":4};
JSONobj.node4 = [];
JSONobj.node4.push({"x5":5, "x6":6});
If you want to use this object external to JS (e.g. send it to the server), you need to convert it to a JSON string:
var JSONtext = JSON.stringify(JSONobj);
If you want to convert JSON string to a JSON-object in JS, you use:
var JSONobj = JSON.parse(JSONtext);
I met some problem when I use JSON for implementing adjacency list. First thing was, I cant use a 'integer value' as id in the id:value pair . so I rethink about my problem and approached in another way and I implemented the adjacency list as below(as a list of list).
Current solution
The representation of each node of a graph by its cartesian co-ordinates is really a low-level representation. At the algorithm level, we need to associate a single unique number with each vertex; for example, you can map:
I made a list for all vertexes:
eg: nodes = [[100,200],[45,78],[198,213]]
in which nodes[1] gives the coordinates for vertex 1.
And adjacency list is of the form of a list of list.
adj_list = [[1,2,3], [0, 4, 5] ]
adj_list[1] gives you list of nodes adjacent to node1. and so on..
This means: adjacent to (directly connected to) vertex 0, you have vertices 1, 2, 3.
Adjacent to vertex 1, you have vertices 0, 4, 5 ...
I found this solution is more suitable to my problem. Thanks to Dave and Jiri for their reply.
