The avatar for @alainro
Alain Roan
DataViz, Dashboard, Observable Ambassador and Notion Certified
Published
Edited
May 14, 2020
1 fork
21 stars
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draw = (context, points, t) => {
mutable nbtotal = points.length;

if (points.length > nbCities) {
points = points.slice();
d3.quickselect( // very nice suggestion from https://observablehq.com/@fil Thanks!!
points,
nbCities,
0,
points.length - 1,
(a, b) => b.size - a.size
);
points.splice(nbCities, points.length - 1)
}
if (background){
context.globalAlpha = 1
context.drawImage(image, 0, 0, width, height)
context.fill()
}
mutable nbrendered = points.length;
context.globalAlpha = 0.5
context.fillStyle = background ? 'yellow' : 'black'
const k = 1 / 500 / t.k;
for (let i = 0; i < points.length; i++) {
const d = points[i],
v = d.size * k;
context.beginPath();
context.arc(
d[0],
d[1],
Math.sqrt(v),
0,
tau
) // Color, size, anything can be changed.
context.fill()
}

}
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Type JavaScript, then Shift-Enter. Ctrl-space for more options. Arrow ↑/↓ to switch modes.

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image = zoomable('https://raw.githubusercontent.com/toulousedataviz/toulousedataviz.github.io/master/CanvasElectionsx8.png')
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