如何使用d3.js，force和network仅使用一个函数设置cx和cy？

Question

All I found say something like this to change cx,cy :

  .attr("cx", function(d) {var x... return x; })
  .attr("cy", function(d) {var y... return y; })

But I have a function F(x,y) that returns {X:value, Y:value} .

As this F function is computationally expensive, I can't call it twice.

I need something like this:

 node.attr("[cx,cy]", function(d){ return F(d.x,d.y) }

Just set cx and cy calling function F just one time for each node. It is in function tick() . And I think node.attr(...) calls the function for each node automatically, that's why I don't execute the function F before the node.attr(...) line.

Is there any way to do that?

Answer 1

You could pre-compute the values once and store them in your data objects:

data.forEach(function (d) {
    var result = F(d.x, d.y);
    d.computedX = result[0];
    d.computedY = result[1];
});

And then later:

node.attr("cx", function(d) { return d.computedX; })
    .attr("cy", function(d) { return d.computedY; })