Syntax for Vega-lite: viewof chart = vegalite({ "width": 360, "height": 200, "data": {"values":data}, "layer": [{ "selection": { "brush": { "type": "interval", "encodings": ["x"] } }, "mark": "bar", "encoding": { "x": { "field": "name", "type": "ordinal" }, "y": { "field": "value", "type": "quantitative" }, "opacity": { "condition": { "selection": "brush", "value": 1 }, "value": 0.7 } } }] })