Custom Chart
The Custom Chart Block is an advanced Block that allows you to create custom data visualization by utilizing your choice of Vega or Vega-Lite.
If you would like a specific visualization that’s not already a WEGnology Dashboard Block, the Custom Chart Block supports a wide array of visualization types like Scatterplots, Bubble Plots, or even layer visualizations together.
Configuration
Configuring the Custom Chart Block is broken up into two sections:
Queries
All query types include a Query Name property which is how each individual query’s data is referenced in the Vega/Vega-Lite configuration.
Time Series Queries
Time series queries provides a dataset that includes the value of a single attribute from a selected device over a duration of time at a selected resolution. The values returned from the query will be returned as an array of objects in the form of:
[
{ "time": <time>, "value": <value> },
{ "time": <time>, "value": <value> },
{ "time": <time>, "value": <value> }
]The values returned will reflect the selected attribute’s value specified at the reported time. This is the same data that is used in the Time Series Block.
The parameters of the Time Series Query include:
- Query Name is what will be referenced in the Vega/Vega-Lite configuration in order to access the returned dataset.
- Device IDS / Tags is a device query for choosing which devices’ data you want to access.
- Attribute is the device attribute whose value will be returned in the query. Note that if data from more than one device is being displayed, each of those devices must supply the same attribute name.
- Duration is how far into the past you want to look at the data.
- Resolution is how your data will be grouped. These options will change based on what you specify for the duration.
- Aggregation determines how all the available data in each resolution group should be aggregated before being read. For example, “Mean” averages all data points together before displaying in the gauge.
Gauge Queries
Gauge Queries allow you to query a single attribute from a selected device. You can choose to return either the last reported value of the attribute or the value from a selected aggregation over a selected duration of time.
This query returns an object in the form of { "time": <time>, "value": <value> }. The value of time in the returned data is the time that the query was made and the value of value is the data of the attribute after the selected aggregation has been performed.
The parameters of the Gauge Query include:
- Query Name is what will be referenced in the Vega/Vega-Lite configuration in order to access the returned dataset.
- Device IDS / Tags is a device query for choosing which devices’ data you want to access.
- Attribute is the device attribute whose value will be returned in the query. Note that if data from more than one device is being displayed, each of those devices must supply the same attribute name.
- Duration is how far into the past you want to look at the data.
-
Aggregation determines how all the available data returned should be aggregated before being read. For example, “Mean” averages all data points together before displaying in the gauge. This field is only available if “Data Type” is set to “Historical”, and any of the following conditions applies:
- Duration is set to anything other than “Last received data point.”
- A device tag is supplied in the device query.
- More than one device ID is supplied within the device query.
Data Table Queries
Data table queries allow you to query any data that is stored on a data table. The data table query will return an array of your data table rows where the column names will be the keys you will reference. We will automatically generate a list of columns that are available to query as well as all default row data.
Building this query is done the same way as building a query in the Table: Get Rows Node, where an array of individual queries can be joined with an “OR” or “AND” operator.
Vega/Vega-Lite Configuration
Once you have a query, you will have to choose what version of Vega or Vega-Lite you want to use for your chart and write a custom configuration for your chart.
The $schema field will be added automatically based on the Vega/Vega-Lite version. The default block configuration will be sized to the Dashboard Block size and is not valid as you will have to provide the data.
When referencing a query, it is a Vega Named Data Source based on the what is entered in the “Query Name” field. All queries will be formatted as JSON data; no need to set a data format in your configuration.
Keep in mind that you can use any valid Vega/Vega-Lite Data Source to populate your chart, not just any of your previously created queries.
For more information on configuring Vega/Vega-Lite, please reference the documentation for the Vega/Vega-Lite version you choose to use. WEGnology provides support for the following versions:
Examples
The examples provided below are written using Vega/Vega-Lite v2.
Time Series Bar Chart
{
"width": {{block.width}},
"height": {{block.height}},
"autosize": {
"type": "fit",
"contains": "padding"
},
"description": "A simple time series bar chart.",
"data": {
"name": "time-series-0"
},
"mark": "bar",
"encoding": {
"x": {
"field": "time",
"type": "temporal",
"timeUnit": "minutes"
},
"y": {
"field": "value",
"type": "quantitative",
"axis": {"title": "Cents"}
}
}
}Layered Time Series Line Chart with Gauge as Average Line
{
"width": {{block.width}},
"height": {{block.height}},
"autosize": {
"type": "fit",
"contains": "padding"
},
"layer": [
{
"data": {
"name": "time-series-0"
},
"mark": "line",
"encoding": {
"x": {
"field": "time",
"type": "temporal"
},
"y": {
"field": "value",
"type": "quantitative",
"axis": {
"title": "Cents"
}
}
}
},
{
"data": {
"name": "gauge-0"
},
"mark": "rule",
"encoding": {
"y": {
"field": "value",
"type": "quantitative"
},
"size": {"value": 2}
}
}
]
}Data Table Scatter Plot
{
"width": {{block.width}},
"height": {{block.height}},
"autosize": {
"type": "fit",
"contains": "padding"
},
"description": "A simple time series bar chart.",
"data": {
"name": "data-table-0"
},
"mark": "point",
"encoding": {
"x": {
"field": "PlaceholderNumber",
"type": "quantitative"
},
"y": {
"field": "PlaceholderNumber2",
"type": "quantitative"
}
}
}