Hello Hong,

Probably the easiest option to change just one link path (I assume that is what you mean by a bar) is to use a d3.select statement to access the element and change it by using a filter to get the specific data element. Something like this:

d3.selectAll(“.vz-weighted_tree-link”).filter(function (d) {
return (d.someAttribute == someValue)
})
.style(“fill”,myNewColor);

– Tom