Multivariate Local Geary

Multivariate local geary (2019) is a multivariate extension of local geary which measures the extent to which neighbors in multiattribute space are also neighbors in geographical space. For more information, please read: https://geodacenter.github.io/workbook/6c_local_multi/lab6c.html

localMultiGeary()

function localMultiGeary(
    WeightResult w,
    Array vals,
    Number permutations, 
    String permutation_method,
    NUmber significance_cutoff, 
    Number seed)

Arguments

Name	Type	Description
w	WeightResult	the WeightResult object created from weights function
vals	Array	an array of the numeric columns that contains the values for LISA statistics
permutations	Number	the number of permutations for the LISA computation. Default: 999.
permutation_method	String	the permutation method used for the LISA computation. Options are 'complete', 'lookup'. Default: 'lookup'.
significance_cutoff	Number	the cutoff value for significance p-values to filter not-significant clusters. Default: 0.05.
seed	Number	the seed for random number generator used in LISA statistics. Default: 123456789.

Return

Type	Description
LisaResult	The LisaResult object contains the results of LISA computation: pvalues, clusters, lisa_values, neighbors, labels, colors

Examples

Node.js

const jsgeoda = require('jsgeoda');
const fs = require('fs');

// load data
const data = fs.readFileSync('./data/natregimes.geojson').buffer;

// create jsgeoda instance
const geoda = await jsgeoda.New();

// load geojson in jsgeoda
const nat = geoda.readGeoJSON(data);

// create a queen contiguity weights
const w = geoda.getQueenWeights(nat);

// get HR60 values
const hr60 = geoda.getColumn(nat, "HR60");
const ue60 = geoda.getColumn(nat, "UE60");
        
// multivariate local geary statistics 
const lm = geoda.localMultiGeary(w, [hr60, ue60]);

React

import React, { Component } from "react";
import ReactDOM from "react-dom";
import DeckGL from "@deck.gl/react";
import { GeoJsonLayer } from "@deck.gl/layers";
import { StaticMap } from "react-map-gl";
import colorbrewer from "colorbrewer";
import jsgeoda from "jsgeoda";

// Set your mapbox access token here
const MAPBOX_TOKEN =
  "pk.eyJ1IjoibGl4dW45MTAiLCJhIjoiY2locXMxcWFqMDAwenQ0bTFhaTZmbnRwaiJ9.VRNeNnyb96Eo-CorkJmIqg";

// The geojson data
const DATA_URL = `https://webgeoda.github.io/data/natregimes.geojson`;

class App extends Component {
  constructor() {
    super();
    this.state = {
      mapId: "",
      layer: null,
      viewPort: {
        longitude: -100.4,
        latitude: 38.74,
        zoom: 2.5,
        maxZoom: 20
      }
    };
  }

  // load spatial data when mount this component
  loadSpatialData(geoda) {
    fetch(DATA_URL)
      .then((res) => res.arrayBuffer())
      .then((data) => {
        // load geojson in jsgeoda, an unique id (string) will be returned for further usage
        const nat = geoda.readGeoJSON(data);
        const w = geoda.getQueenWeights(nat);
        const hr60 = geoda.getColumn(nat, "HR60");
        const ue60 = geoda.getColumn(nat, "UE60");
        const lm = geoda.localMultiGeary(w, [hr60, ue60]);

        const lm_colors = lm.colors.map((c) =>
          c
            .toLowerCase()
            .match(/[0-9a-f]{2}/g)
            .map((x) => parseInt(x, 16))
        );
        // Viewport settings
        const view_port = geoda.get_viewport(
          nat,
          window.innerHeight,
          window.innerWidth
        );

        // Create GeoJsonLayer
        const layer = new GeoJsonLayer({
          id: "GeoJsonLayer",
          data: DATA_URL,
          filled: true,
          getFillColor: (f) => this.getFillColor(f, lm.clusters, lm_colors),
          stroked: true,
          pickable: true
        });

        // Trigger to draw map
        this.setState({
          mapId: nat,
          layer: layer,
          viewPort: view_port
        });
      });
  }

  componentDidMount() {
    // jsgeoda.New() function will create an instance from WASM
    jsgeoda.New().then((geoda) => {
      this.loadSpatialData(geoda);
    });
  }

  // Determine which color for which geometry
  getFillColor(f, clusters, colors) {
    const i = f.properties.POLY_ID - 1;
    const c = clusters[i];
    return colors[c];
  }

  render() {
    return (
      <div>
        <DeckGL
          initialViewState={this.state.viewPort}
          layers={[this.state.layer]}
          controller={true}
          getTooltip={({ object }) =>
            object && `${object.properties.NAME}: ${object.properties.HR60}`
          }
        >
          <StaticMap mapboxApiAccessToken={MAPBOX_TOKEN} />
        </DeckGL>
      </div>
    );
  }
}

ReactDOM.render(<App />, document.getElementById("root"));

Try it yourself in the playground (jsgeoda + deck.gl):