redash/client/app/visualizations/map/prepareData.js

import d3 from 'd3';
import { isNil, extend, map, filter, groupBy, omit } from 'lodash';

export default function prepareData(data, options) {
  const colorScale = d3.scale.category10();

  const { classify, latColName, lonColName } = options;

  const pointGroups = classify ? groupBy(data.rows, classify) : { All: data.rows };

  return filter(map(pointGroups, (rows, name) => {
    const points = filter(map(rows, (row) => {
      const lat = row[latColName];
      const lon = row[lonColName];
      if (isNil(lat) || isNil(lon)) {
        return null;
      }
      return { lat, lon, row: omit(row, [latColName, lonColName]) };
    }));
    if (points.length === 0) {
      return null;
    }

    const result = extend({}, options.groups[name], { name, points });
    if (isNil(result.color)) {
      result.color = colorScale(name);
    }

    return result;
  }));
}