d3 circle pack: setting circle colors

Question

I try to use http://mbostock.github.com/d3/ex/bubble.html but with changed colors.

I would like to find out how the colors are set in d3.layout.pack.

Answer 1

In the example you mentioned, the circle color is defined here:

.style("fill", function(d) { return fill(d.packageName); });

Here, d is the data, bound to the circle.
Instead of color, in this example the function passes an object (packageName attribute of d).
Each object gets own unique color assigned to it, according to selected color scale:

fill = d3.scale.category20c();

If you are happy with used criteria for coloring (packageName) and all you need is to change colors, you could change the palette (color scale):
https://github.com/mbostock/d3/wiki/Ordinal-Scales

if you want to change the coloring criteria, then you need to change the return part, replacing it with color value as a function of data d.

Here you can find D3 color constructors:
https://github.com/mbostock/d3/wiki/Colors