Documentation
The Vega visualization grammar provides basic building blocks for a wide variety of visualization designs. This page provides documentation of Vega JSON specifications and JavaScript API.
To start learning Vega, we recommend first working through the introductory Let’s Make A Bar Chart tutorial and exploring the example gallery, then digging into the documentation. These pages document Vega version 3.0 and later; if you are familiar with Vega 2.x, you might begin with the Vega 2 porting guide.
Specification Reference
A Vega specification is a JSON object that describes an interactive visualization design. A specification consists of basic properties (such as the width and height of the view) and definitions for the data to visualize, scales that map data values to visual values, axes and legends that visualize these scales, cartographic projections for drawing maps, graphical marks such as rectangles, lines, and symbols to visually represent data, and signals to process user input and modify the visualization in response.
| Specification | Overview of a full Vega specification, including sizing and metadata. |
| Config | Configure defaults for visual encoding choices. |
| Data | Define, load, and parse data to visualize. |
| Transforms | Apply data transforms (filter, sort, aggregate, layout) prior to visualization. |
| Triggers | Modify data sets or mark properties in response to signal values. |
| Projections | Cartographic projections to map (longitude, latitude) data. |
| Scales | Map data values (numbers, strings) to visual properties (coordinates, colors, sizes). |
| Schemes | Color schemes that can be used as scale ranges. |
| Axes | Visualize scale mappings for spatial encodings using coordinate axes. |
| Legends | Visualize scale mappings for color, shape and size encodings. |
| Title | Specify a chart title for a visualization. |
| Marks | Visually encode data with graphical marks such as rectangles, lines, and symbols. |
| Signals | Dynamic variables that can drive interactive updates. |
| Event Streams | Define input event streams to specify interactions. |
| Expressions | Express custom calculations over data and signals. |
| Layout | Perform grid layout for a collection of group marks. |
| Types | Documentation of recurring parameter types. |
Vega API Reference
Vega also provides a JavaScript runtime API, responsible for parsing JSON specifications to produce interactive views backed by a reactive dataflow graph of data processing operators. For more on deploying Vega, see the usage instructions.
| Parser | Parse Vega JSON specifications to dataflow descriptions. |
| View | Create interactive views from dataflow descriptions. |
| Locale | Use number and date formats for a specific locale. |
| Extensibility | Extend Vega with new projections, scales, color schemes, or data transforms. |
| Statistics | Statistical methods used by Vega. |
| Time | Utility methods for date-time values. |
| Util | General JavaScript utilities. |
| Debugging | A guide to debugging Vega visualizations at runtime. |