Summary
Despite the near mythical power of D3 layouts, they turn out to be nothing more than helpers that turn your data into a collection of coordinates. We've used the hierarchical layouts to create a boatload of different charts, without much more than a few lines of code differing between implementations.
These charts are so simple, we could have really extended our base object a lot to be far more abstracted; so by doing things such as fixating colors and adding the legend during the init() method -- between chapter6/index and common/index -- we've added probably around 600 lines, and we could probably reduce that by a couple of hundred. However, it's also useful to create each chart separately to reinforce the workflow needed by the hierarchical layouts, as I've done in this chapter.
In the next chapter, we'll look at a few more layouts. They'll look pretty familiar to the hierarchical ones in terms of how we write them, but we'll be flipping around the data a fair bit more to accommodate...
