Vega-Lite Cross-Filter Example / Vega

Data Visualization Languages & Tools

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Edited

Nov 13, 2022

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{

// create one interval brush for each histogram

const brushDelay = vl.selectInterval('delay').encodings('x');

const brushDist = vl.selectInterval('dist').encodings('x');

const brushTime = vl.selectInterval('time').encodings('x');

// function that creates a histogram visualization

function hist(field, brush, crossfilter) {

// binned x-axis encoding

const x = vl.x()

.fieldQ(field)

.bin({maxbins: 100, minstep: 1}).stack(false)

.axis({title: field, titleAnchor: 'start', format: 'd'});

return vl.layer(

// transparent base layer with unfiltered data

vl.markBar().select(brush)

.encode(x, vl.detail().count(), vl.color().value('transparent')),

// cross-filtered histogram bars

vl.markBar().transform(vl.filter(crossfilter))

.encode(x, vl.y().count().axis(null))

)

.width(width - 10)

.height(100);

}

// vconcat three cross-filtered histograms

return vl.vconcat(

hist('delay', brushDelay, vl.and(brushDist, brushTime)),

hist('distance', brushDist, vl.and(brushDelay, brushTime)),

hist('time', brushTime, vl.and(brushDelay, brushDist))

)

.data('data/flights-10k.json')

.transform(vl.calculate('hours(datum.date) + minutes(datum.date) / 60').as('time'))

.config({view: {stroke: null}})

.render();

}

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