Filter Transform

The filter transform removes objects from a data stream based on a provided filter expression or filter object.

// Any View Specification
{
  ...
  "transform": [
    {"filter": ...} // Filter Transform
     ...
  ],
  ...
}

Vega-Lite filter transforms must have the filter property describing the predicate for the filtering condition.

Property Type Description

filter

Property	Type	Description
filter	Predicate	*Required.* The `filter` property must be a predication definition, which can take one of the following forms: 1) an expression string, where `datum` can be used to refer to the current data object. For example, `{filter: "datum.b2 > 60"}` would make the output data includes only items that have values in the field `b2` over 60. 2) one of the field predicates: `equal`, `lt`, `lte`, `gt`, `gte`, `range`, `oneOf`, or `valid`, 3) a selection predicate, which define the names of a selection that the data point should belong to (or a logical composition of selections). 4) a logical composition of (1), (2), or (3).

Predicate

Required. The filter property must be a predication definition, which can take one of the following forms:

1) an expression string, where datum can be used to refer to the current data object. For example, {filter: "datum.b2 > 60"} would make the output data includes only items that have values in the field b2 over 60.

2) one of the field predicates: equal, lt, lte, gt, gte, range, oneOf, or valid,

3) a selection predicate, which define the names of a selection that the data point should belong to (or a logical composition of selections).

4) a logical composition of (1), (2), or (3).