Refactor chart components for composability

[brylie]

Currently, the developer documentation is limited to a set of high-level chart types, such as LinetWithFocusChart. This makes it simple to use NVD3, but is difficult to define/modify custom chart types.

Feature request

For any significant refactoring of the NVD3 codebase, it may be worthwhile to design a high-level composable API (and corresponding documentation), so that custom chart types could be constructed, declaratively, from chart components.

Component types

There would be several generic component types useful when constructing custom charts. Some examples, borrowed from other libraries include:

• data - generic data structure to
  • transformations - support common methods such as parsing, aggregating, filtering, (i.e. much less pre-processing of data would be necessary from the developer, allowing them to use more declarative code style), scaling values
• layout - rules for combining chart elements including relationship with parent DOM
• chart components -
  • primary - bar, line, pie, scatter
  • auxiliary - legend, axis, title, subtitle, annotations
  • users can declaratively select dimensions to pass in to chart elements
• aesthetics - declarative rules for element style
  • markers and composite markers
• events - common code for chart interaction such as brushing, panning, selection, etc
  • signals - allowing for intra-component communication (e.g. integrated dashboard for exploratory data analysis)

    Examples

There are some other charting libraries, and JavaScript frameworks, taking the route of composability, namely:

• ggplot2 - composable charting library for R-Language
• Vega - a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs.

[brylie]

Possibly related to issue #1794