Question

My problem is as follows. I have an array of objects in the form of source/target from a graph (these are the id’s of the node). It looks like this:

[{"source": 1053, "target": 845, "value": 751}, {"source": 845, "target": 862, "value": 751}, {"source": 1053, "target": 611, "value": 751}, {"source": 1053, "target": 611, "value": 751}, {"source": 1054, "target": 905, "value": 17}, {"source": 1055, "target": 837, "value": 8}, {"source": 1055, "target": 837, "value": 8}, {"source": 1055, "target": 837, "value": 8}, {"source": 1055, "target": 400, "value": 8}, {"source": 1055, "target": 400, "value": 8}, {"source": 1055, "target": 400, "value": 8}]

Now: For a certain node id I would like to know all its children and the subsequent subchildren of these children and so on, all the way down. It works for the first “generation”, but then I would need to iterate over the targets again and again. How do I accomplish this?

nodes = [1053]
function getChildren(nodes, links) {
    var children = [];
    $.each(links, function(key, link) {
        if (nodes.indexOf(link.source) > -1) {
            children.push(link.target);
        }
    });
    return children;
}

Answer 1

The recursion would look like:

1. Get all children of the given node
2. if one of them is new to your result array
   • get all of its children and add them
3. return the result

…which would be a simple depth-first search.

function getAllLinkedTo(nodes) {
    var result = [];
    for (var i=0; i<nodes.length; i++)
        getChildren(nodes[i]);
    function getChildren(node) {
        if (result.indexOf(node) > -1)
            return;
        result.push(node);
        for (var i=0; i<links.length; i++) // a source -> targets mapping object would be beneficial
            if (links[i].source == node)
                getChildren(links[i].target);
    }
    return result;
}

You could also accomplish this with a loop over result, which may be faster.