a solution to the challenge of the Helikar Lab GSoC2017

gridLayout.js

function gridLayout() {}

gridLayout.calculate = function(nodes, edges, size) {
    var degrees = Array(nodes.length).fill(0);
    edges.forEach(function(e) {
	degrees[e.source.index] += 1;
	degrees[e.target.index] += 1;
    });

    //getting the order of nodes from highest to lowest degrees
    var mapped = degrees.map(function(el, i) {
        return { index: i, value: el };
    });
    mapped.sort(function(a, b) {
        return +(a.value < b.value) || +(a.value === b.value) - 1;
    });
    //illustrating how one would sort 'degrees' by 'mapped'
    //result = mapped.map(function(el){
    //    return degrees[el.index];
    //});

    //positions should spiral around the center:
    var spiral = makeSpiral(nodes.length, Math.floor(size/2));
    mapped.forEach(function(e, i){
	aindex = e.index;
	nodes[aindex].x = spiral[i][0];
	nodes[aindex].y = spiral[i][1];
    });
}

function makeSpiral(n, center){
    //(di, dj) is a vector - direction in which we move right now
    var di = 1;
    var dj = 0;
    //length of current segment
    var segment_length = 1;
    //current position (i, j) and how much of current segment we passed
    var i = center;
    var j = center;
    var segment_passed = 0;
    var positions = [[i, j]];
    var abuffer = 0;
    for (k = 0; k < n-1; ++k) {
	//make a step, add 'direction' vector (di, dj) to current position (i, j)
	i += di;
	j += dj;
	++segment_passed;
	positions.push([i, j]);
	if (segment_passed == segment_length) {
	    //done with current segment
	    segment_passed = 0;
	    //'rotate' directions
	    abuffer = di;
	    di = -dj;
	    dj = abuffer;
	    //increase segment length if necessary
	    if (dj == 0) {
		++segment_length;
	    }
	}
	}
	return positions;
}