Créer une carte choroplèthe

Une carte choroplèthe est un type de carte thématique dans laquelle les régions administratives sont colorées ou nuancées en fonction d'une plage statistique. Vous pouvez utiliser google.maps.FeatureStyleFunction pour styliser une carte en fonction d'un ensemble de données, chaque région administrative étant associée à une valeur numérique. L'exemple de carte suivant montre une carte choroplèthe représentant les données de population de chaque État des États-Unis.

Dans cet exemple, les données sont constituées d'un tableau de paires clé/valeur, correspondant au nom à afficher de chaque État avec une valeur numérique de population. La maps.FeatureStyleFunction colore de manière conditionnelle chaque région en fonction des valeurs du tableau.

TypeScript

featureLayer.style = featureStyleFunctionOptions => {
    const placeFeature = featureStyleFunctionOptions.feature as google.maps.PlaceFeature;
    const population = states[placeFeature.placeId];

    let fillColor;
    // Specify colors using any of the following:
    // * Named ('green')
    // * Hexadecimal ('#FF0000')
    // * RGB ('rgb(0, 0, 255)')
    // * HSL ('hsl(60, 100%, 50%)')

    if (population < 2000000) {
        fillColor = 'green'
    } else if (population < 5000000) {
        fillColor = 'red'
    } else if (population < 10000000) {
        fillColor = 'blue'
    } else if (population < 40000000) {
        fillColor = 'yellow'
    }
    return {
        fillColor,
        fillOpacity: 0.5
    }
}

// Population data by state.
const states = {
    "ChIJdf5LHzR_hogR6czIUzU0VV4": 5039877, // Alabama
    "ChIJG8CuwJzfAFQRNduKqSde27w": 732673, // Alaska
    "ChIJaxhMy-sIK4cRcc3Bf7EnOUI": 7276316, // Arizona
    "ChIJYSc_dD-e0ocR0NLf_z5pBaQ": 3025891, // Arkansas
    "ChIJPV4oX_65j4ARVW8IJ6IJUYs": 39237836, // California
    "ChIJt1YYm3QUQIcR_6eQSTGDVMc": 5812069, // Colorado
    "ChIJpVER8hFT5okR5XBhBVttmq4": 3605597, // Connecticut
    "ChIJO9YMTXYFx4kReOgEjBItHZQ": 1003384, // Delaware
    "ChIJvypWkWV2wYgR0E7HW9MTLvc": 21781128, // Florida
    "ChIJV4FfHcU28YgR5xBP7BC8hGY": 10799566, // Georgia
    "ChIJBeB5Twbb_3sRKIbMdNKCd0s": 1441553, // Hawaii
    "ChIJ6Znkhaj_WFMRWIf3FQUwa9A": 1900923, // Idaho
    "ChIJGSZubzgtC4gRVlkRZFCCFX8": 12671469, // Illinois
    "ChIJHRv42bxQa4gRcuwyy84vEH4": 6805985, // Indiana
    "ChIJGWD48W9e7ocR2VnHV0pj78Y": 3193079, // Iowa
    "ChIJawF8cXEXo4cRXwk-S6m0wmg": 2934582, // Kansas
    "ChIJyVMZi0xzQogR_N_MxU5vH3c": 4509394, // Kentucky
    "ChIJZYIRslSkIIYRA0flgTL3Vck": 4624047, // Louisiana
    "ChIJ1YpTHd4dsEwR0KggZ2_MedY": 1372247, // Maine
    "ChIJ35Dx6etNtokRsfZVdmU3r_I": 6165129, // Maryland
    "ChIJ_b9z6W1l44kRHA2DVTbQxkU": 6984723, // Massachussetts
    "ChIJEQTKxz2qTE0Rs8liellI3Zc": 10050811, // Michigan
    "ChIJmwt4YJpbWE0RD6L-EJvJogI": 5707390, // Minnesota
    "ChIJGdRK5OQyKIYR2qbc6X8XDWI": 2949965, // Mississippi
    "ChIJfeMiSNXmwIcRcr1mBFnEW7U": 6168187, // Misssouri
    "ChIJ04p7LZwrQVMRGGwqz1jWcfU": 1104271, // Montana
    "ChIJ7fwMtciNk4cRxArzDwyQJ6E": 1963692, // Nebraska
    "ChIJcbTe-KEKmYARs5X8qooDR88": 3143991, // Nevada
    "ChIJ66bAnUtEs0wR64CmJa8CyNc": 1388992, // New Hampshire
    "ChIJn0AAnpX7wIkRjW0_-Ad70iw": 9267130, // New Jersey
    "ChIJqVKY50NQGIcRup41Yxpuv0Y": 2115877, // New Mexico
    "ChIJqaUj8fBLzEwRZ5UY3sHGz90": 19835913, // New York
    "ChIJgRo4_MQfVIgRGa4i6fUwP60": 10551162, // North Carolina
    "ChIJY-nYVxKD11IRyc9egzmahA0": 774948, // North Dakota
    "ChIJwY5NtXrpNogRFtmfnDlkzeU": 11780017, // Ohio
    "ChIJnU-ssRE5rIcRSOoKQDPPHF0": 3986639, // Oklahoma
    "ChIJVWqfm3xuk1QRdrgLettlTH0": 4246155, // Oregon
    "ChIJieUyHiaALYgRPbQiUEchRsI": 12964056, // Pennsylvania
    "ChIJD9cOYhQ15IkR5wbB57wYTh4": 1095610, // Rhode Island
    "ChIJ49ExeWml-IgRnhcF9TKh_7k": 5190705, // South Carolina
    "ChIJpTjphS1DfYcRt6SGMSnW8Ac": 895376, // South Dakota
    "ChIJA8-XniNLYYgRVpGBpcEgPgM": 6975218, // Tennessee
    "ChIJSTKCCzZwQIYRPN4IGI8c6xY": 29527941, // Texas
    "ChIJzfkTj8drTIcRP0bXbKVK370": 3337975, // Utah
    "ChIJ_87aSGzctEwRtGtUNnSJTSY": 645570, // Vermont
    "ChIJzbK8vXDWTIgRlaZGt0lBTsA": 8642274, // Virginia
    "ChIJ-bDD5__lhVQRuvNfbGh4QpQ": 7738692, // Washington
    "ChIJRQnL1KVUSogRQzrN3mjHALs": 1782959, // West Virginia
    "ChIJr-OEkw_0qFIR1kmG-LjV1fI": 5895908, // Wisconsin
    "ChIJaS7hSDTiXocRLzh90nkisCY": 578803, // Wyoming
};

JavaScript

featureLayer.style = (featureStyleFunctionOptions) => {
  const placeFeature = featureStyleFunctionOptions.feature;
  const population = states[placeFeature.placeId];
  let fillColor;

  // Specify colors using any of the following:
  // * Named ('green')
  // * Hexadecimal ('#FF0000')
  // * RGB ('rgb(0, 0, 255)')
  // * HSL ('hsl(60, 100%, 50%)')
  if (population < 2000000) {
    fillColor = "green";
  } else if (population < 5000000) {
    fillColor = "red";
  } else if (population < 10000000) {
    fillColor = "blue";
  } else if (population < 40000000) {
    fillColor = "yellow";
  }
  return {
    fillColor,
    fillOpacity: 0.5,
  };
};

// Population data by state.
const states = {
  "ChIJdf5LHzR_hogR6czIUzU0VV4": 5039877,
  "ChIJG8CuwJzfAFQRNduKqSde27w": 732673,
  "ChIJaxhMy-sIK4cRcc3Bf7EnOUI": 7276316,
  "ChIJYSc_dD-e0ocR0NLf_z5pBaQ": 3025891,
  "ChIJPV4oX_65j4ARVW8IJ6IJUYs": 39237836,
  "ChIJt1YYm3QUQIcR_6eQSTGDVMc": 5812069,
  "ChIJpVER8hFT5okR5XBhBVttmq4": 3605597,
  "ChIJO9YMTXYFx4kReOgEjBItHZQ": 1003384,
  "ChIJvypWkWV2wYgR0E7HW9MTLvc": 21781128,
  "ChIJV4FfHcU28YgR5xBP7BC8hGY": 10799566,
  "ChIJBeB5Twbb_3sRKIbMdNKCd0s": 1441553,
  "ChIJ6Znkhaj_WFMRWIf3FQUwa9A": 1900923,
  "ChIJGSZubzgtC4gRVlkRZFCCFX8": 12671469,
  "ChIJHRv42bxQa4gRcuwyy84vEH4": 6805985,
  "ChIJGWD48W9e7ocR2VnHV0pj78Y": 3193079,
  "ChIJawF8cXEXo4cRXwk-S6m0wmg": 2934582,
  "ChIJyVMZi0xzQogR_N_MxU5vH3c": 4509394,
  "ChIJZYIRslSkIIYRA0flgTL3Vck": 4624047,
  "ChIJ1YpTHd4dsEwR0KggZ2_MedY": 1372247,
  "ChIJ35Dx6etNtokRsfZVdmU3r_I": 6165129,
  "ChIJ_b9z6W1l44kRHA2DVTbQxkU": 6984723,
  "ChIJEQTKxz2qTE0Rs8liellI3Zc": 10050811,
  "ChIJmwt4YJpbWE0RD6L-EJvJogI": 5707390,
  "ChIJGdRK5OQyKIYR2qbc6X8XDWI": 2949965,
  "ChIJfeMiSNXmwIcRcr1mBFnEW7U": 6168187,
  "ChIJ04p7LZwrQVMRGGwqz1jWcfU": 1104271,
  "ChIJ7fwMtciNk4cRxArzDwyQJ6E": 1963692,
  "ChIJcbTe-KEKmYARs5X8qooDR88": 3143991,
  "ChIJ66bAnUtEs0wR64CmJa8CyNc": 1388992,
  "ChIJn0AAnpX7wIkRjW0_-Ad70iw": 9267130,
  "ChIJqVKY50NQGIcRup41Yxpuv0Y": 2115877,
  "ChIJqaUj8fBLzEwRZ5UY3sHGz90": 19835913,
  "ChIJgRo4_MQfVIgRGa4i6fUwP60": 10551162,
  "ChIJY-nYVxKD11IRyc9egzmahA0": 774948,
  "ChIJwY5NtXrpNogRFtmfnDlkzeU": 11780017,
  "ChIJnU-ssRE5rIcRSOoKQDPPHF0": 3986639,
  "ChIJVWqfm3xuk1QRdrgLettlTH0": 4246155,
  "ChIJieUyHiaALYgRPbQiUEchRsI": 12964056,
  "ChIJD9cOYhQ15IkR5wbB57wYTh4": 1095610,
  "ChIJ49ExeWml-IgRnhcF9TKh_7k": 5190705,
  "ChIJpTjphS1DfYcRt6SGMSnW8Ac": 895376,
  "ChIJA8-XniNLYYgRVpGBpcEgPgM": 6975218,
  "ChIJSTKCCzZwQIYRPN4IGI8c6xY": 29527941,
  "ChIJzfkTj8drTIcRP0bXbKVK370": 3337975,
  "ChIJ_87aSGzctEwRtGtUNnSJTSY": 645570,
  "ChIJzbK8vXDWTIgRlaZGt0lBTsA": 8642274,
  "ChIJ-bDD5__lhVQRuvNfbGh4QpQ": 7738692,
  "ChIJRQnL1KVUSogRQzrN3mjHALs": 1782959,
  "ChIJr-OEkw_0qFIR1kmG-LjV1fI": 5895908,
  "ChIJaS7hSDTiXocRLzh90nkisCY": 578803, // Wyoming
};

Exemple de code complet

TypeScript

function initMap() {
    const map = new google.maps.Map(document.getElementById('map') as HTMLElement, {
        center: { lat: 40.76, lng: -101.64 },
        zoom: 5,
        // In the cloud console, configure this Map ID with a style that enables the
        // "Administrative Area Level 1" feature layer.
        mapId: '7ba16be0c9375fa7',
    });

    //@ts-ignore
    const featureLayer = map.getFeatureLayer(google.maps.FeatureType.ADMINISTRATIVE_AREA_LEVEL_1);

    featureLayer.style = featureStyleFunctionOptions => {
        const placeFeature = featureStyleFunctionOptions.feature as google.maps.PlaceFeature;
        const population = states[placeFeature.placeId];

        let fillColor;
        // Specify colors using any of the following:
        // * Named ('green')
        // * Hexadecimal ('#FF0000')
        // * RGB ('rgb(0, 0, 255)')
        // * HSL ('hsl(60, 100%, 50%)')

        if (population < 2000000) {
            fillColor = 'green'
        } else if (population < 5000000) {
            fillColor = 'red'
        } else if (population < 10000000) {
            fillColor = 'blue'
        } else if (population < 40000000) {
            fillColor = 'yellow'
        }
        return {
            fillColor,
            fillOpacity: 0.5
        }
    }

    // Population data by state.
    const states = {
        "ChIJdf5LHzR_hogR6czIUzU0VV4": 5039877, // Alabama
        "ChIJG8CuwJzfAFQRNduKqSde27w": 732673, // Alaska
        "ChIJaxhMy-sIK4cRcc3Bf7EnOUI": 7276316, // Arizona
        "ChIJYSc_dD-e0ocR0NLf_z5pBaQ": 3025891, // Arkansas
        "ChIJPV4oX_65j4ARVW8IJ6IJUYs": 39237836, // California
        "ChIJt1YYm3QUQIcR_6eQSTGDVMc": 5812069, // Colorado
        "ChIJpVER8hFT5okR5XBhBVttmq4": 3605597, // Connecticut
        "ChIJO9YMTXYFx4kReOgEjBItHZQ": 1003384, // Delaware
        "ChIJvypWkWV2wYgR0E7HW9MTLvc": 21781128, // Florida
        "ChIJV4FfHcU28YgR5xBP7BC8hGY": 10799566, // Georgia
        "ChIJBeB5Twbb_3sRKIbMdNKCd0s": 1441553, // Hawaii
        "ChIJ6Znkhaj_WFMRWIf3FQUwa9A": 1900923, // Idaho
        "ChIJGSZubzgtC4gRVlkRZFCCFX8": 12671469, // Illinois
        "ChIJHRv42bxQa4gRcuwyy84vEH4": 6805985, // Indiana
        "ChIJGWD48W9e7ocR2VnHV0pj78Y": 3193079, // Iowa
        "ChIJawF8cXEXo4cRXwk-S6m0wmg": 2934582, // Kansas
        "ChIJyVMZi0xzQogR_N_MxU5vH3c": 4509394, // Kentucky
        "ChIJZYIRslSkIIYRA0flgTL3Vck": 4624047, // Louisiana
        "ChIJ1YpTHd4dsEwR0KggZ2_MedY": 1372247, // Maine
        "ChIJ35Dx6etNtokRsfZVdmU3r_I": 6165129, // Maryland
        "ChIJ_b9z6W1l44kRHA2DVTbQxkU": 6984723, // Massachussetts
        "ChIJEQTKxz2qTE0Rs8liellI3Zc": 10050811, // Michigan
        "ChIJmwt4YJpbWE0RD6L-EJvJogI": 5707390, // Minnesota
        "ChIJGdRK5OQyKIYR2qbc6X8XDWI": 2949965, // Mississippi
        "ChIJfeMiSNXmwIcRcr1mBFnEW7U": 6168187, // Misssouri
        "ChIJ04p7LZwrQVMRGGwqz1jWcfU": 1104271, // Montana
        "ChIJ7fwMtciNk4cRxArzDwyQJ6E": 1963692, // Nebraska
        "ChIJcbTe-KEKmYARs5X8qooDR88": 3143991, // Nevada
        "ChIJ66bAnUtEs0wR64CmJa8CyNc": 1388992, // New Hampshire
        "ChIJn0AAnpX7wIkRjW0_-Ad70iw": 9267130, // New Jersey
        "ChIJqVKY50NQGIcRup41Yxpuv0Y": 2115877, // New Mexico
        "ChIJqaUj8fBLzEwRZ5UY3sHGz90": 19835913, // New York
        "ChIJgRo4_MQfVIgRGa4i6fUwP60": 10551162, // North Carolina
        "ChIJY-nYVxKD11IRyc9egzmahA0": 774948, // North Dakota
        "ChIJwY5NtXrpNogRFtmfnDlkzeU": 11780017, // Ohio
        "ChIJnU-ssRE5rIcRSOoKQDPPHF0": 3986639, // Oklahoma
        "ChIJVWqfm3xuk1QRdrgLettlTH0": 4246155, // Oregon
        "ChIJieUyHiaALYgRPbQiUEchRsI": 12964056, // Pennsylvania
        "ChIJD9cOYhQ15IkR5wbB57wYTh4": 1095610, // Rhode Island
        "ChIJ49ExeWml-IgRnhcF9TKh_7k": 5190705, // South Carolina
        "ChIJpTjphS1DfYcRt6SGMSnW8Ac": 895376, // South Dakota
        "ChIJA8-XniNLYYgRVpGBpcEgPgM": 6975218, // Tennessee
        "ChIJSTKCCzZwQIYRPN4IGI8c6xY": 29527941, // Texas
        "ChIJzfkTj8drTIcRP0bXbKVK370": 3337975, // Utah
        "ChIJ_87aSGzctEwRtGtUNnSJTSY": 645570, // Vermont
        "ChIJzbK8vXDWTIgRlaZGt0lBTsA": 8642274, // Virginia
        "ChIJ-bDD5__lhVQRuvNfbGh4QpQ": 7738692, // Washington
        "ChIJRQnL1KVUSogRQzrN3mjHALs": 1782959, // West Virginia
        "ChIJr-OEkw_0qFIR1kmG-LjV1fI": 5895908, // Wisconsin
        "ChIJaS7hSDTiXocRLzh90nkisCY": 578803, // Wyoming
    };
}

declare global {
    interface Window {
        initMap: () => void;
    }
}
window.initMap = initMap;

JavaScript

function initMap() {
  const map = new google.maps.Map(document.getElementById("map"), {
    center: { lat: 40.76, lng: -101.64 },
    zoom: 5,
    // In the cloud console, configure this Map ID with a style that enables the
    // "Administrative Area Level 1" feature layer.
    mapId: "7ba16be0c9375fa7",
  });
  //@ts-ignore
  const featureLayer = map.getFeatureLayer(
    google.maps.FeatureType.ADMINISTRATIVE_AREA_LEVEL_1
  );

  featureLayer.style = (featureStyleFunctionOptions) => {
    const placeFeature = featureStyleFunctionOptions.feature;
    const population = states[placeFeature.placeId];
    let fillColor;

    // Specify colors using any of the following:
    // * Named ('green')
    // * Hexadecimal ('#FF0000')
    // * RGB ('rgb(0, 0, 255)')
    // * HSL ('hsl(60, 100%, 50%)')
    if (population < 2000000) {
      fillColor = "green";
    } else if (population < 5000000) {
      fillColor = "red";
    } else if (population < 10000000) {
      fillColor = "blue";
    } else if (population < 40000000) {
      fillColor = "yellow";
    }
    return {
      fillColor,
      fillOpacity: 0.5,
    };
  };

  // Population data by state.
  const states = {
    "ChIJdf5LHzR_hogR6czIUzU0VV4": 5039877,
    "ChIJG8CuwJzfAFQRNduKqSde27w": 732673,
    "ChIJaxhMy-sIK4cRcc3Bf7EnOUI": 7276316,
    "ChIJYSc_dD-e0ocR0NLf_z5pBaQ": 3025891,
    "ChIJPV4oX_65j4ARVW8IJ6IJUYs": 39237836,
    "ChIJt1YYm3QUQIcR_6eQSTGDVMc": 5812069,
    "ChIJpVER8hFT5okR5XBhBVttmq4": 3605597,
    "ChIJO9YMTXYFx4kReOgEjBItHZQ": 1003384,
    "ChIJvypWkWV2wYgR0E7HW9MTLvc": 21781128,
    "ChIJV4FfHcU28YgR5xBP7BC8hGY": 10799566,
    "ChIJBeB5Twbb_3sRKIbMdNKCd0s": 1441553,
    "ChIJ6Znkhaj_WFMRWIf3FQUwa9A": 1900923,
    "ChIJGSZubzgtC4gRVlkRZFCCFX8": 12671469,
    "ChIJHRv42bxQa4gRcuwyy84vEH4": 6805985,
    "ChIJGWD48W9e7ocR2VnHV0pj78Y": 3193079,
    "ChIJawF8cXEXo4cRXwk-S6m0wmg": 2934582,
    "ChIJyVMZi0xzQogR_N_MxU5vH3c": 4509394,
    "ChIJZYIRslSkIIYRA0flgTL3Vck": 4624047,
    "ChIJ1YpTHd4dsEwR0KggZ2_MedY": 1372247,
    "ChIJ35Dx6etNtokRsfZVdmU3r_I": 6165129,
    "ChIJ_b9z6W1l44kRHA2DVTbQxkU": 6984723,
    "ChIJEQTKxz2qTE0Rs8liellI3Zc": 10050811,
    "ChIJmwt4YJpbWE0RD6L-EJvJogI": 5707390,
    "ChIJGdRK5OQyKIYR2qbc6X8XDWI": 2949965,
    "ChIJfeMiSNXmwIcRcr1mBFnEW7U": 6168187,
    "ChIJ04p7LZwrQVMRGGwqz1jWcfU": 1104271,
    "ChIJ7fwMtciNk4cRxArzDwyQJ6E": 1963692,
    "ChIJcbTe-KEKmYARs5X8qooDR88": 3143991,
    "ChIJ66bAnUtEs0wR64CmJa8CyNc": 1388992,
    "ChIJn0AAnpX7wIkRjW0_-Ad70iw": 9267130,
    "ChIJqVKY50NQGIcRup41Yxpuv0Y": 2115877,
    "ChIJqaUj8fBLzEwRZ5UY3sHGz90": 19835913,
    "ChIJgRo4_MQfVIgRGa4i6fUwP60": 10551162,
    "ChIJY-nYVxKD11IRyc9egzmahA0": 774948,
    "ChIJwY5NtXrpNogRFtmfnDlkzeU": 11780017,
    "ChIJnU-ssRE5rIcRSOoKQDPPHF0": 3986639,
    "ChIJVWqfm3xuk1QRdrgLettlTH0": 4246155,
    "ChIJieUyHiaALYgRPbQiUEchRsI": 12964056,
    "ChIJD9cOYhQ15IkR5wbB57wYTh4": 1095610,
    "ChIJ49ExeWml-IgRnhcF9TKh_7k": 5190705,
    "ChIJpTjphS1DfYcRt6SGMSnW8Ac": 895376,
    "ChIJA8-XniNLYYgRVpGBpcEgPgM": 6975218,
    "ChIJSTKCCzZwQIYRPN4IGI8c6xY": 29527941,
    "ChIJzfkTj8drTIcRP0bXbKVK370": 3337975,
    "ChIJ_87aSGzctEwRtGtUNnSJTSY": 645570,
    "ChIJzbK8vXDWTIgRlaZGt0lBTsA": 8642274,
    "ChIJ-bDD5__lhVQRuvNfbGh4QpQ": 7738692,
    "ChIJRQnL1KVUSogRQzrN3mjHALs": 1782959,
    "ChIJr-OEkw_0qFIR1kmG-LjV1fI": 5895908,
    "ChIJaS7hSDTiXocRLzh90nkisCY": 578803, // Wyoming
  };
}

window.initMap = initMap;

CSS

/*
 * Always set the map height explicitly to define the size of the div element
 * that contains the map.
 */
#map {
  height: 100%;
}

/*
 * Optional: Makes the sample page fill the window.
 */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

HTML

<html>
  <head>
    <title>Choropleth Map</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
  </head>
  <body>
    <div id="map"></div>

    <!--
      The `defer` attribute causes the callback to execute after the full HTML
      document has been parsed. For non-blocking uses, avoiding race conditions,
      and consistent behavior across browsers, consider loading using Promises.
      See https://developers.google.com/maps/documentation/javascript/load-maps-js-api
      for more information.
      -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=beta"
      defer
    ></script>
  </body>
</html>

Essayer l'exemple