AZP

The automatic zoning procedure (AZP) was initially outlined in Openshaw (1977) as a way to address some of the consequences of the modifiable areal unit problem (MAUP). In essence, it consists of a heuristic to find the best set of combinations of contiguous spatial units into p regions, minimizing the within sum of squares as a criterion of homogeneity. The number of regions needs to be specified beforehand.

azpGreedy()

A simulated annealing algorithm to solve the AZP problem

function azpGreedy(
    WeightResult w,
    Number k, 
    Array vals,
    Number inits,
    Array init_region,
    Array min_bound_values, 
    Array min_bounds,
    Array max_bound_values, 
    Array max_bounds,
    String scale_method,
    String distance_type,
    Number seed)

Arguments

Name	Type	Description
weights	WeightsResult	The weights object WeightsResult
k	Number	The number of spatially constrained clusters
vals	Array	The list of numeric vectors of the selected variable.
inits	Number	The number of construction re-runs, which is for ARiSeL "automatic regionalization with initial seed location"
init_region	Array	The initial regions that the local search starts with. Default is empty. means the local search starts with a random process to "grow" clusters
min_bounds_values	Array	The list of numeric array of selected minimum bounding variables.
min_bounds	Array	The list of minimum values that the sum value of bounding variables in each cluster should be greater than.
max_bounds_values	Array	The list of numeric arrays of selected maximum bounding variables.
max_bounds	Array	The list of minimum value that the sum value of bounding variables in each cluster should be less than.
scale_method	String	The scaling methods {'raw', 'standardize', 'demean', 'mad', 'range_standardize', 'range_adjust'}. Defaults to 'standardize'.
distance_method	String	The distance methods {"euclidean", "manhattan"}. Defaults to 'euclidean'.
seed	Number	The seed for random number generator.

Return

Type	Description
ClusteringResult	The Clustering object: {'total_ss', 'within_ss', 'between_ss', 'ratio', 'clusters'}

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 values
const hr60 = geoda.getColumn(nat, "HR60");
const ue60 = geoda.getColumn(nat, "UE60");

// set minimum bound
const po60 = geoda.getColumn(nat, "PO60");

// apply azp_greedy
const inits = 1;
const init_region = [];
const min_bound_vals = [po60];
const min_bounds = [17845200];
const azp = geoda.azpGreedy(w, 20, [hr60, ue60], inits, init_region, min_bound_vals,min_bounds);

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.read_geojson(data);
        const w = geoda.queen_weights(nat);
        const hr60 = geoda.get_col(nat, "HR60");
        const ue60 = geoda.get_col(nat, "UE60");
        const po60 = geoda.get_col(nat, "PO60");
        const redcap = geoda.skater(w, 10, [hr60, ue60], 17845200, po60);
        //const redcap = geoda.schc(w, 10, [hr60, ue60], 'ward', 17845200, po60);
        //const redcap = geoda.redcap(w, 10, [hr60, ue60], "fullorder-wardlinkage", 17845200, po60);
        //const azp = geoda.azp_greedy(w, 20, [hr60, ue60], 1, [], [po60],[17845200]);
        //const redcap = geoda.azp_tabu(w, 20, [hr60, ue60], 10, 10, 1, [], [po60],[17845200]);
        //const redcap = geoda.azp_sa(w, 20, [hr60, ue60], 0.85, 1, 1, [], [po60],[17845200]);
        //const redcap = geoda.maxp_greedy(w, [hr60, ue60],  1, [po60],[17845200]);
        const colors = colorbrewer["Paired"][10].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, redcap.clusters, 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] - 1;
    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):

azpSA()

A simulated annealing algorithm to solve the AZP problem

function azpSA(
    WeightResult w,
    Number k, 
    Array vals,
    Number cooling_rate,
    Number sa_maxit,
    Number inits,
    Array init_region,
    Array min_bound_values, 
    Array min_bounds,
    Array max_bound_values, 
    Array max_bounds,
    String scale_method,
    String distance_type,
    Number seed)

Arguments

Name	Type	Description
weights	WeightsResult	The weights object WeightsResult
k	Number	The number of spatially constrained clusters
vals	Array	The list of numeric vectors of selected variable.
cooling_rate	Number	The number of iterations of simulated annealing. Defaults to 1
sa_maxit	Number	The number of iterations of simulated annealing. Defaults to 1
inits	Number	The number of construction re-runs, which is for ARiSeL "automatic regionalization with initial seed location"
init_region	Array	The initial regions that the local search starts with. Default is empty. means the local search starts with a random process to "grow" clusters
min_bounds_values	Array	The list of numeric array of selected minimum bounding variables.
min_bounds	Array	The list of minimum value that the sum value of bounding variables in each cluster should be greater than.
max_bounds_values	Array	The list of numeric array of selected maximum bounding variables.
max_bounds	Array	The list of minimum value that the sum value of bounding variables in each cluster should be less than.
scale_method	String	The scaling methods {'raw', 'standardize', 'demean', 'mad', 'range_standardize', 'range_adjust'}. Defaults to 'standardize'.
distance_method	String	The distance methods {"euclidean", "manhattan"}. Defaults to 'euclidean'.
seed	Number	The seed for random number generator.

Return

Type	Description
ClusteringResult	The Clustering object: {'total_ss', 'within_ss', 'between_ss', 'ratio', 'clusters'}

azpTabu()

A tabu algorithm to solve the AZP problem

function azpTabu(
    WeightResult w,
    Number k, 
    Array vals,
    Number tabu_length,
    Number conv_tabu,
    Number inits,
    Array init_region,
    Array min_bound_values, 
    Array min_bounds,
    Array max_bound_values, 
    Array max_bounds,
    String scale_method,
    String distance_type,
    Number seed)

Arguments

Name	Type	Description
weights	WeightsResult	The weights object WeightsResult
k	Number	The number of spatially constrained clusters
values	Array	The list of numeric vectors of selected variable.
tabu_length	Number	The length of a tabu search heuristic of tabu algorithm. Defaults to 10.
conv_tabu	Number	The number of non-improving moves. Defaults to 10.
inits	Number	The number of construction re-runs, which is for ARiSeL "automatic regionalization with initial seed location"
init_region	Array	The initial regions that the local search starts with. Default is empty. means the local search starts with a random process to "grow" clusters
min_bounds_values	Array	The list of numeric array of selected minimum bounding variables.
min_bounds	Array	The list of minimum value that the sum value of bounding variables in each cluster should be greater than.
max_bounds_values	Array	The list of numeric array of selected maximum bounding variables.
max_bounds	Array	The list of minimum value that the sum value of bounding variables in each cluster should be less than.
scale_method	String	The scaling methods {'raw', 'standardize', 'demean', 'mad', 'range_standardize', 'range_adjust'}. Defaults to 'standardize'.
distance_method	String	The distance methods {"euclidean", "manhattan"}. Defaults to 'euclidean'.
seed	Number	The seed for random number generator.

Return

Type	Description
ClusteringResult	The Clustering object: {'total_ss', 'within_ss', 'between_ss', 'ratio', 'clusters'}