Consider buffer radius in addition to H3 resolution when counting points in the aggregated bins of H3-hexagons

[sharmapn]

Hello,

I am focussing on the H3-JS example from
https://observablehq.com/@nrabinowitz/h3-tutorial-using-point-layers?collection=@nrabinowitz/h3-tutorial

Within the provided code, there is a function (below) that counts the number of points in each of the hexagons after the binning and embeds these as attributes within the geoJSON.

function _countPoints(h3,h3Resolution,normalizeLayer){return(
function countPoints(geojson) {
  const layer = {};
  geojson.features.forEach(feature => {
    const [lng, lat] = feature.geometry.coordinates;
    const h3Index = h3.geoToH3(lat, lng, h3Resolution);
    layer[h3Index] = (layer[h3Index] || 0) + 1;
  });
  return normalizeLayer(layer, true);
}
)}

However, in addition to the h3Resolution, I was hoping to integrate Buffer Radius in this calculation.
You see I am fully using the example. Thus, the user can choose values for both: h3Resolution and Buffer Radius.
That means that the resulting geojson should shoe the counts after considering both the values: h3Resolution and Buffer Radius.

Finally we need a geojson which has the features, together with the h3 cells, h3 resolution, buffer radius and the number of points contained within.

I would appreciate any guidance on this small question.

[nrabinowitz]

I'm not clear on what's intended here. Is the Buffer Radius in grid distance? I.e. if I run countPoints(res, radius) you want the count of all points that are both in the specific h3 cell and in its neighbors at a given radius?

This could look like:

function countPoints(geojson, h3Resolution, bufferRadius) {
  const layer = {};
  geojson.features.forEach(feature => {
    const [lng, lat] = feature.geometry.coordinates;
    const h3Index = h3.geoToH3(lat, lng, h3Resolution);
    const neighbors = h3.kRing(h3Index, bufferRadius);
    for (const neighbor of neighbors) {
      layer[neighbor] = (layer[neighbor] || 0) + 1;
    }
  });
  return normalizeLayer(layer, true);
}

[sharmapn]

Yes, that is what I needed.
Thank you.