vega-lite/src/compile/data/geopoint.ts

Vega-Lite is a concise high-level language for interactive visualization.

import {GeoPointTransform as VgGeoPointTransform, Vector2} from 'vega';
import {isString} from 'vega-util';
import {GeoPositionChannel, LATITUDE, LATITUDE2, LONGITUDE, LONGITUDE2} from '../../channel.js';
import {getFieldOrDatumDef, isDatumDef, isFieldDef, isValueDef} from '../../channeldef.js';
import {duplicate, hash} from '../../util.js';
import {VgExprRef} from '../../vega.schema.js';
import {UnitModel} from '../unit.js';
import {DataFlowNode} from './dataflow.js';

export class GeoPointNode extends DataFlowNode {
  public clone() {
    return new GeoPointNode(null, this.projection, duplicate(this.fields), duplicate(this.as));
  }

  constructor(
    parent: DataFlowNode,
    private projection: string,
    private fields: [string | VgExprRef, string | VgExprRef],
    private as: [string, string],
  ) {
    super(parent);
  }

  public static parseAll(parent: DataFlowNode, model: UnitModel): DataFlowNode {
    if (!model.projectionName()) {
      return parent;
    }

    for (const coordinates of [
      [LONGITUDE, LATITUDE],
      [LONGITUDE2, LATITUDE2],
    ] as Vector2<GeoPositionChannel>[]) {
      const pair = coordinates.map((channel) => {
        const def = getFieldOrDatumDef(model.encoding[channel]);
        return isFieldDef(def)
          ? def.field
          : isDatumDef(def)
            ? {expr: `${def.datum}`}
            : isValueDef(def)
              ? {expr: `${def['value']}`}
              : undefined;
      }) as [GeoPositionChannel, GeoPositionChannel];

      const suffix = coordinates[0] === LONGITUDE2 ? '2' : '';

      if (pair[0] || pair[1]) {
        parent = new GeoPointNode(parent, model.projectionName(), pair, [
          model.getName(`x${suffix}`),
          model.getName(`y${suffix}`),
        ]);
      }
    }

    return parent;
  }

  public dependentFields() {
    return new Set(this.fields.filter(isString));
  }

  public producedFields() {
    return new Set(this.as);
  }

  public hash() {
    return `Geopoint ${this.projection} ${hash(this.fields)} ${hash(this.as)}`;
  }

  public assemble(): VgGeoPointTransform {
    return {
      type: 'geopoint',
      projection: this.projection,
      fields: this.fields,
      as: this.as,
    };
  }
}