Repeat a View

The repeat operator is part of Vega-Lite’s view composition. It provides a shortcut that creates a view for each entry in an array of fields. This operator generates multiple plots like facet. However, unlike facet it allows full replication of a data set in each view.

Documentation Overview

• Repeat Operator
• Row/Column/Layer Repeat Mapping
• Examples
  • Repeated Line Charts
  • Multi-series Line Chart with Repeated Layers
  • Repeated Histogram (Wrapped)
  • Scatterplot Matrix (SPLOM)
• Resolve
• Repeat Configuration

Repeat Operator

To repeat a view, define what fields should be used for each entry. Then define the repeated view in spec with a reference to a repeated field ({"repeat": ...}).

{
  "repeat": {
    ... // Repeat definition
  },
  "spec": ... // Specification
}

In addition to common properties of a view specification, a repeat specification has the following properties:

Row/Column/Layer Repeat Mapping

The repeat property can be an object with at least one of "row", "column" and "layer" properties, which define the list of fields that should be repeated into a row, a column, or a layer.

Note that when you repeat views into layers, the views are superimposed. Even if different layers use different colors, Vega-Lite will not generate a legend and not stack marks such as bars or areas. If you want a legend or stack different fields, use the fold transform to convert your data to long form and then use a color encoding.

Examples

Repeated Line Charts

For instance, you can use this operator to quickly create an overview over the trends in multiple variables.

Note how the field for the y channel refers to a repeated field.

"y": {
  "field": {"repeat": "repeat"}
  ...
},

Multi-series Line Chart with Repeated Layers

You can also use repeat with layer to create a multi-series line chart. Here we map a repeater field as data value (datum) for the color encoding.

Repeated Histogram (Wrapped)

Scatterplot Matrix (SPLOM)

Repeat can be used to create a scatterplot matrix (SPLOM), where each cell shows a different 2D projection of the same data table. Here, we define both row and column.

You can also check the interactive SPLOM example.

Resolve

The default resolutions for repeat are independent scales and axes for position channels and shared scales and legends for all other channels. Currently, Vega-Lite does not support shared axes for repeated views.

Repeat Configuration

Since repeat is a shorthand for concatenation, the concat configuration is also used for repeated views.

// Top-level View Specification
{
  ...,
  "config": { // Configuration Object

    "concat": { // - Concat Configuration
      "spacing": ...,
      "columns": ...,
    },
    ...
  }
}

The repeat configuration supports the following properties: