Parameter Types

Reference documentation for common parameter types expected by Vega-Lite specification properties.

Parameter Type Reference

Any
Array
Boolean
Color
DateTime
Expression
Number
Object
String
URL

Literal Values

# Any or *

Accepts any literal value, including a string, number, boolean, or null.

# Array or Type[]

Accepts array values. For example: [], [1, 2, 3], ["foo", "bar"]. If individual array items must adhere to a specific type, bracket notation – such as Number[] or String[] – is used to indicate the item type.

In most cases, arrays may also have signal references as items. For example: [{"signal": "width"}, {"signal": "height"}].

# Boolean

Accepts boolean values. For example: true, false.

# Color

Accepts a valid CSS color string. For example: #f304d3, #ccc, rgb(253, 12, 134), steelblue.

# DateTime

A DateTime object (in filter transform, scale domain, and axis/legend values) must have at least one of the following properties:

Property	Type	Description
year	Number	Integer value representing the year.
quarter	Number	Integer value representing the quarter of the year (from 1-4).
month	Number \| String	One of: (1) integer value representing the month from `1`-`12`. `1` represents January; (2) case-insensitive month name (e.g., `"January"`); (3) case-insensitive, 3-character short month name (e.g., `"Jan"`).
date	Number	Integer value representing the date from 1-31.
day	Number \| String	Value representing the day of a week. This can be one of: (1) integer value – `1` represents Monday; (2) case-insensitive day name (e.g., `"Monday"`); (3) case-insensitive, 3-character short day name (e.g., `"Mon"`). Warning: A DateTime definition object with `day`** should not be combined with `year`, `quarter`, `month`, or `date`.
hours	Number	Integer value representing the hour of a day from 0-23.
minutes	Number	Integer value representing the minute segment of time from 0-59.
seconds	Number	Integer value representing the second segment (0-59) of a time value
milliseconds	Number	Integer value representing the millisecond segment of time.

For example {"year": 2006, "month": "jan", "date": 1} represents Jan 1, 2006.

# Expression

To enable custom calculations, Vega-Lite uses Vega’s expression language for writing basic formulas. Each datum object can be referred using bound variable datum.

Please read the Vega documentation for expressions for details.

# Number

Accepts number values. For example: 1, 3.14, 1e5.

# Object

Accepts object literals. For example: {"left":5, "right":30, "top":5, "bottom":50}. The valid object property names and types will vary across parameters; read the individual parameter descriptions for more information.

# String

Accepts string values. For example: "bold", "step-before", "".

# URL

Accepts a valid URL string linking to external site or resource. For example: "data/stocks.csv", "images/logo.png", "https://vega.github.io/".