Data

This section of the specification is to configure and define the data to load and its type. By default, Vega is configured to use a tabular data structure with collections of rows as records and columns as fields. Data can either be directly loaded through the values property or through url as shown below:

“data”: [{"name": "temperature", "values": [244.85, 50.74, 2.95, 1.25, 44.04, 116.34]}] “data”: [{"name": "stats", "url": "data/playerStats.json", “transform”: [ ]}]

Apart from these basic configurations, it is also possible to specify the format of data to load (csv, tsv, json). The transform section is used to define how to render the data being loaded. Data transforms operations are executed over the given dataset before rendering the visualisation. Its main purpose is to define the encoding mechanism and to filter, group, sort or define the custom formula. Each transform section should have type property, which defines the type of transformation to be performed and some set of properties. Some examples are shown below:

"transform": [ {"type": "copy", "from": "data", "fields": ["source", "target"]} {"type": "filter", "test": "data.score > 100"} {"type": "formula", "field": "rectArea", "expr": "data. length*data.width"}

]