Panoramica
Questo tutorial ti mostra come visualizzare su una mappa Google i dati provenienti da più origini. Ad esempio, la mappa coropletica riportata di seguito utilizza due diverse origini per evidenziare i vari stati degli Stati Uniti e visualizzare i dati specifici degli stati.
La mappa utilizza i dati di un file GeoJSON per visualizzare i poligoni che definiscono i confini degli stati degli Stati Uniti. Può anche presentare dati sulla mappa corrispondenti a ogni stato, provenienti da una query simulata all'API US Census.
Seleziona una categoria di dati dal menu a discesa del controllo per aggiornare i poligoni sulla mappa. Puoi anche passare il mouse sopra un poligono di stato per visualizzare informazioni specifiche di uno stato in un controllo della casella dati sulla mappa.
Il seguente esempio mostra l'intero codice necessario per creare questa mappa.
TypeScript
const mapStyle: google.maps.MapTypeStyle[] = [ { stylers: [{ visibility: "off" }], }, { featureType: "landscape", elementType: "geometry", stylers: [{ visibility: "on" }, { color: "#fcfcfc" }], }, { featureType: "water", elementType: "geometry", stylers: [{ visibility: "on" }, { color: "#bfd4ff" }], }, ]; let map: google.maps.Map; let censusMin = Number.MAX_VALUE, censusMax = -Number.MAX_VALUE; function initMap(): void { // load the map map = new google.maps.Map(document.getElementById("map") as HTMLElement, { center: { lat: 40, lng: -100 }, zoom: 4, styles: mapStyle, }); // set up the style rules and events for google.maps.Data map.data.setStyle(styleFeature); map.data.addListener("mouseover", mouseInToRegion); map.data.addListener("mouseout", mouseOutOfRegion); // wire up the button const selectBox = document.getElementById( "census-variable" ) as HTMLSelectElement; google.maps.event.addDomListener(selectBox, "change", () => { clearCensusData(); loadCensusData(selectBox.options[selectBox.selectedIndex].value); }); // state polygons only need to be loaded once, do them now loadMapShapes(); } /** Loads the state boundary polygons from a GeoJSON source. */ function loadMapShapes() { // load US state outline polygons from a GeoJson file map.data.loadGeoJson( "https://storage.googleapis.com/mapsdevsite/json/states.js", { idPropertyName: "STATE" } ); // wait for the request to complete by listening for the first feature to be // added google.maps.event.addListenerOnce(map.data, "addfeature", () => { google.maps.event.trigger( document.getElementById("census-variable") as HTMLElement, "change" ); }); } /** * Loads the census data from a simulated API call to the US Census API. * * @param {string} variable */ function loadCensusData(variable: string) { // load the requested variable from the census API (using local copies) const xhr = new XMLHttpRequest(); xhr.open("GET", variable + ".json"); xhr.onload = function () { const censusData = JSON.parse(xhr.responseText) as any; censusData.shift(); // the first row contains column names censusData.forEach((row: string) => { const censusVariable = parseFloat(row[0]); const stateId = row[1]; // keep track of min and max values if (censusVariable < censusMin) { censusMin = censusVariable; } if (censusVariable > censusMax) { censusMax = censusVariable; } const state = map.data.getFeatureById(stateId); // update the existing row with the new data if (state) { state.setProperty("census_variable", censusVariable); } }); // update and display the legend (document.getElementById("census-min") as HTMLElement).textContent = censusMin.toLocaleString(); (document.getElementById("census-max") as HTMLElement).textContent = censusMax.toLocaleString(); }; xhr.send(); } /** Removes census data from each shape on the map and resets the UI. */ function clearCensusData() { censusMin = Number.MAX_VALUE; censusMax = -Number.MAX_VALUE; map.data.forEach((row) => { row.setProperty("census_variable", undefined); }); (document.getElementById("data-box") as HTMLElement).style.display = "none"; (document.getElementById("data-caret") as HTMLElement).style.display = "none"; } /** * Applies a gradient style based on the 'census_variable' column. * This is the callback passed to data.setStyle() and is called for each row in * the data set. Check out the docs for Data.StylingFunction. * * @param {google.maps.Data.Feature} feature */ function styleFeature(feature: google.maps.Data.Feature) { const low = [5, 69, 54]; // color of smallest datum const high = [151, 83, 34]; // color of largest datum // delta represents where the value sits between the min and max const delta = (feature.getProperty("census_variable") - censusMin) / (censusMax - censusMin); const color: number[] = []; for (let i = 0; i < 3; i++) { // calculate an integer color based on the delta color.push((high[i] - low[i]) * delta + low[i]); } // determine whether to show this shape or not let showRow = true; if ( feature.getProperty("census_variable") == null || isNaN(feature.getProperty("census_variable")) ) { showRow = false; } let outlineWeight = 0.5, zIndex = 1; if (feature.getProperty("state") === "hover") { outlineWeight = zIndex = 2; } return { strokeWeight: outlineWeight, strokeColor: "#fff", zIndex: zIndex, fillColor: "hsl(" + color[0] + "," + color[1] + "%," + color[2] + "%)", fillOpacity: 0.75, visible: showRow, }; } /** * Responds to the mouse-in event on a map shape (state). * * @param {?google.maps.MapMouseEvent} e */ function mouseInToRegion(e: any) { // set the hover state so the setStyle function can change the border e.feature.setProperty("state", "hover"); const percent = ((e.feature.getProperty("census_variable") - censusMin) / (censusMax - censusMin)) * 100; // update the label (document.getElementById("data-label") as HTMLElement).textContent = e.feature.getProperty("NAME"); (document.getElementById("data-value") as HTMLElement).textContent = e.feature .getProperty("census_variable") .toLocaleString(); (document.getElementById("data-box") as HTMLElement).style.display = "block"; (document.getElementById("data-caret") as HTMLElement).style.display = "block"; (document.getElementById("data-caret") as HTMLElement).style.paddingLeft = percent + "%"; } /** * Responds to the mouse-out event on a map shape (state). * */ function mouseOutOfRegion(e: any) { // reset the hover state, returning the border to normal e.feature.setProperty("state", "normal"); } declare global { interface Window { initMap: () => void; } } window.initMap = initMap;
JavaScript
const mapStyle = [ { stylers: [{ visibility: "off" }], }, { featureType: "landscape", elementType: "geometry", stylers: [{ visibility: "on" }, { color: "#fcfcfc" }], }, { featureType: "water", elementType: "geometry", stylers: [{ visibility: "on" }, { color: "#bfd4ff" }], }, ]; let map; let censusMin = Number.MAX_VALUE, censusMax = -Number.MAX_VALUE; function initMap() { // load the map map = new google.maps.Map(document.getElementById("map"), { center: { lat: 40, lng: -100 }, zoom: 4, styles: mapStyle, }); // set up the style rules and events for google.maps.Data map.data.setStyle(styleFeature); map.data.addListener("mouseover", mouseInToRegion); map.data.addListener("mouseout", mouseOutOfRegion); // wire up the button const selectBox = document.getElementById("census-variable"); google.maps.event.addDomListener(selectBox, "change", () => { clearCensusData(); loadCensusData(selectBox.options[selectBox.selectedIndex].value); }); // state polygons only need to be loaded once, do them now loadMapShapes(); } /** Loads the state boundary polygons from a GeoJSON source. */ function loadMapShapes() { // load US state outline polygons from a GeoJson file map.data.loadGeoJson( "https://storage.googleapis.com/mapsdevsite/json/states.js", { idPropertyName: "STATE" }, ); // wait for the request to complete by listening for the first feature to be // added google.maps.event.addListenerOnce(map.data, "addfeature", () => { google.maps.event.trigger( document.getElementById("census-variable"), "change", ); }); } /** * Loads the census data from a simulated API call to the US Census API. * * @param {string} variable */ function loadCensusData(variable) { // load the requested variable from the census API (using local copies) const xhr = new XMLHttpRequest(); xhr.open("GET", variable + ".json"); xhr.onload = function () { const censusData = JSON.parse(xhr.responseText); censusData.shift(); // the first row contains column names censusData.forEach((row) => { const censusVariable = parseFloat(row[0]); const stateId = row[1]; // keep track of min and max values if (censusVariable < censusMin) { censusMin = censusVariable; } if (censusVariable > censusMax) { censusMax = censusVariable; } const state = map.data.getFeatureById(stateId); // update the existing row with the new data if (state) { state.setProperty("census_variable", censusVariable); } }); // update and display the legend document.getElementById("census-min").textContent = censusMin.toLocaleString(); document.getElementById("census-max").textContent = censusMax.toLocaleString(); }; xhr.send(); } /** Removes census data from each shape on the map and resets the UI. */ function clearCensusData() { censusMin = Number.MAX_VALUE; censusMax = -Number.MAX_VALUE; map.data.forEach((row) => { row.setProperty("census_variable", undefined); }); document.getElementById("data-box").style.display = "none"; document.getElementById("data-caret").style.display = "none"; } /** * Applies a gradient style based on the 'census_variable' column. * This is the callback passed to data.setStyle() and is called for each row in * the data set. Check out the docs for Data.StylingFunction. * * @param {google.maps.Data.Feature} feature */ function styleFeature(feature) { const low = [5, 69, 54]; // color of smallest datum const high = [151, 83, 34]; // color of largest datum // delta represents where the value sits between the min and max const delta = (feature.getProperty("census_variable") - censusMin) / (censusMax - censusMin); const color = []; for (let i = 0; i < 3; i++) { // calculate an integer color based on the delta color.push((high[i] - low[i]) * delta + low[i]); } // determine whether to show this shape or not let showRow = true; if ( feature.getProperty("census_variable") == null || isNaN(feature.getProperty("census_variable")) ) { showRow = false; } let outlineWeight = 0.5, zIndex = 1; if (feature.getProperty("state") === "hover") { outlineWeight = zIndex = 2; } return { strokeWeight: outlineWeight, strokeColor: "#fff", zIndex: zIndex, fillColor: "hsl(" + color[0] + "," + color[1] + "%," + color[2] + "%)", fillOpacity: 0.75, visible: showRow, }; } /** * Responds to the mouse-in event on a map shape (state). * * @param {?google.maps.MapMouseEvent} e */ function mouseInToRegion(e) { // set the hover state so the setStyle function can change the border e.feature.setProperty("state", "hover"); const percent = ((e.feature.getProperty("census_variable") - censusMin) / (censusMax - censusMin)) * 100; // update the label document.getElementById("data-label").textContent = e.feature.getProperty("NAME"); document.getElementById("data-value").textContent = e.feature .getProperty("census_variable") .toLocaleString(); document.getElementById("data-box").style.display = "block"; document.getElementById("data-caret").style.display = "block"; document.getElementById("data-caret").style.paddingLeft = percent + "%"; } /** * Responds to the mouse-out event on a map shape (state). * */ function mouseOutOfRegion(e) { // reset the hover state, returning the border to normal e.feature.setProperty("state", "normal"); } window.initMap = initMap;
CSS
html, body, #map { height: 100%; margin: 0; padding: 0; overflow: hidden; } .nicebox { position: absolute; text-align: center; font-family: "Roboto", "Arial", sans-serif; font-size: 13px; z-index: 5; box-shadow: 0 4px 6px -4px #333; padding: 5px 10px; background: rgb(255, 255, 255); background: linear-gradient(to bottom, rgb(255, 255, 255) 0%, rgb(245, 245, 245) 100%); border: rgb(229, 229, 229) 1px solid; } #controls { top: 10px; left: 110px; width: 360px; height: 45px; } #data-box { top: 10px; left: 500px; height: 45px; line-height: 45px; display: none; } #census-variable { width: 360px; height: 20px; } #legend { display: flex; display: -webkit-box; padding-top: 7px; } .color-key { background: linear-gradient(to right, hsl(5, 69%, 54%) 0%, hsl(29, 71%, 51%) 17%, hsl(54, 74%, 47%) 33%, hsl(78, 76%, 44%) 50%, hsl(102, 78%, 41%) 67%, hsl(127, 81%, 37%) 83%, hsl(151, 83%, 34%) 100%); flex: 1; -webkit-box-flex: 1; margin: 0 5px; text-align: left; font-size: 1em; line-height: 1em; } #data-value { font-size: 2em; font-weight: bold; } #data-label { font-size: 2em; font-weight: normal; padding-right: 10px; } #data-label:after { content: ":"; } #data-caret { margin-left: -5px; display: none; font-size: 14px; width: 14px; }
HTML
<html> <head> <title>Mashups with google.maps.Data</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="controls" class="nicebox"> <div> <select id="census-variable"> <option value="https://storage.googleapis.com/mapsdevsite/json/DP02_0066PE" > Percent of population over 25 that completed high school </option> <option value="https://storage.googleapis.com/mapsdevsite/json/DP05_0017E" > Median age </option> <option value="https://storage.googleapis.com/mapsdevsite/json/DP05_0001E" > Total population </option> <option value="https://storage.googleapis.com/mapsdevsite/json/DP02_0016E" > Average family size </option> <option value="https://storage.googleapis.com/mapsdevsite/json/DP03_0088E" > Per-capita income </option> </select> </div> <div id="legend"> <div id="census-min">min</div> <div class="color-key"><span id="data-caret">◆</span></div> <div id="census-max">max</div> </div> </div> <div id="data-box" class="nicebox"> <label id="data-label" for="data-value"></label> <span id="data-value"></span> </div> <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=weekly" defer ></script> </body> </html>
Prova Samples
Come iniziare
Puoi sviluppare la tua versione di questa mappa coropletica utilizzando il codice di questo tutorial.
Per iniziare, crea un nuovo file in un editor di testo e salvalo come index.html
.
Leggi le sezioni seguenti per comprendere il codice che puoi aggiungere a questo file.
Creazione di una mappa base
Questa sezione illustra il codice che imposta una mappa base. La procedura è simile a quella che hai creato per le mappe quando hai iniziato a utilizzare l'API Maps JavaScript.
Copia il codice seguente nel file index.html
. Questo codice carica l'API Maps JavaScript e visualizza la mappa a schermo intero.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<title>Mashups with google.maps.Data</title>
<style>
#map {
height: 100%;
}
/* Optional: Makes the sample page fill the window. */
html, body {
height: 100%;
margin: 0;
padding: 0;
}
</style>
</head>
<body>
<div id="map"></div>
<script>
function initMap() {
// load the map
map = new google.maps.Map(document.getElementById('map'), {
center: {lat: 40, lng: -100},
zoom: 4,
styles: mapStyle
});
var mapStyle = [{
'featureType': 'all',
'elementType': 'all',
'stylers': [{'visibility': 'off'}]
}, {
'featureType': 'landscape',
'elementType': 'geometry',
'stylers': [{'visibility': 'on'}, {'color': '#fcfcfc'}]
}, {
'featureType': 'water',
'elementType': 'labels',
'stylers': [{'visibility': 'off'}]
}, {
'featureType': 'water',
'elementType': 'geometry',
'stylers': [{'visibility': 'on'}, {'hue': '#5f94ff'}, {'lightness': 60}]
}];
}
</script>
<script defer
src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initMap">
</script>
</body>
</html>
Il codice all'interno del primo tag script è il punto di partenza che esegue il programma creando una funzione chiamata initMap
che inizializza l'oggetto mappa.
Gli stili nel codice riportato sopra disattivano la visibilità di tutti gli elementi
featureTypes
sulla mappa, ad esempio strade, punti d'interesse, paesaggi, aree
amministrative e tutti i rispettivi elementTypes
. Per un elenco di tutti i valori disponibili per featureType
e elementType
, consulta le informazioni di riferimento sugli stili JSON.
Fai clic su YOUR_API_KEY
nell'esempio di codice o segui le istruzioni per ottenere una chiave API.
Sostituisci YOUR_API_KEY
con la chiave API dell'applicazione. Una volta che l'API è stata completamente caricata, il parametro di callback nel tag script riportato di seguito esegue la funzione initMap()
nel file HTML.
<script> defer
src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initMap"
</script>
Creazione e stile del controllo mappa
Il codice seguente crea i seguenti controlli sulla mappa:
- Un controllo con un menu a discesa contenente 5 diverse opzioni per i dati.
- Una legenda della mappa.
- Una casella dati che mostra dati specifici di uno stato che viene visualizzata quando passi il mouse sopra un poligono.
<div id="controls" class="nicebox"> <div> <select id="census-variable"> <option value="https://storage.googleapis.com/mapsdevsite/json/DP02_0066PE">Percent of population over 25 that completed high school</option> <option value="https://storage.googleapis.com/mapsdevsite/json/DP05_0017E">Median age</option> <option value="https://storage.googleapis.com/mapsdevsite/json/DP05_0001E">Total population</option> <option value="https://storage.googleapis.com/mapsdevsite/json/DP02_0016E">Average family size</option> <option value="https://storage.googleapis.com/mapsdevsite/json/DP03_0088E">Per-capita income</option> </select> </div> <div id="legend"> <div id="census-min">min</div> <div class="color-key"><span id="data-caret">◆</span></div> <div id="census-max">max</div> </div> </div> <div id="data-box" class="nicebox"> <label id="data-label" for="data-value"></label> <span id="data-value"></span> </div>
Utilizza il codice seguente all'interno dei tag style
per definire lo stile dei controlli della mappa.
<style> html, body, #map { height: 100%; margin: 0; padding: 0; overflow: hidden; } .nicebox { position: absolute; text-align: center; font-family: "Roboto", "Arial", sans-serif; font-size: 13px; z-index: 5; box-shadow: 0 4px 6px -4px #333; padding: 5px 10px; background: rgb(255,255,255); background: linear-gradient(to bottom,rgba(255,255,255,1) 0%,rgba(245,245,245,1) 100%); border: rgb(229, 229, 229) 1px solid; } #controls { top: 10px; left: 110px; width: 360px; height: 45px; } #data-box { top: 10px; left: 500px; height: 45px; line-height: 45px; display: none; } #census-variable { width: 360px; height: 20px; } #legend { display: flex; display: -webkit-box; padding-top: 7px } .color-key { background: linear-gradient(to right, hsl(5, 69%, 54%) 0%, hsl(29, 71%, 51%) 17%, hsl(54, 74%, 47%) 33%, hsl(78, 76%, 44%) 50%, hsl(102, 78%, 41%) 67%, hsl(127, 81%, 37%) 83%, hsl(151, 83%, 34%) 100%); flex: 1; -webkit-box-flex: 1; margin: 0 5px; text-align: left; font-size: 1.0em; line-height: 1.0em; } #data-value { font-size: 2.0em; font-weight: bold } #data-label { font-size: 2.0em; font-weight: normal; padding-right: 10px; } #data-label:after { content: ':' } #data-caret { margin-left: -5px; display: none; font-size: 14px; width: 14px} </style>
Importazione di dati dall'API US Census
Il codice seguente interroga lo US Census Bureau i dati del censimento più recenti di tutti gli stati degli Stati Uniti, che riceve in formato JSON.
function loadCensusData(variable) {
// load the requested variable from the census API
var xhr = new XMLHttpRequest();
xhr.open('GET', 'http://api.census.gov/data/2012/acs5/profile?get=' +
variable + '&for=state:*&key=YOUR_API_KEY');
xhr.onload = function() {
var censusData = JSON.parse(xhr.responseText);
censusData.shift(); // the first row contains column names
censusData.forEach(function(row) {
var censusVariable = parseFloat(row[0]);
var stateId = row[1];
// keep track of min and max values
if (censusVariable < censusMin) {
censusMin = censusVariable;
}
if (censusVariable > censusMax) {
censusMax = censusVariable;
}
// update the existing row with the new data
map.data
.getFeatureById(stateId)
.setProperty('census_variable', censusVariable);
});
// update and display the legend
document.getElementById('census-min').textContent =
censusMin.toLocaleString();
document.getElementById('census-max').textContent =
censusMax.toLocaleString();
};
xhr.send();
}
Applicare uno stile ai dati
Il codice seguente crea la mappa coropletica applicando un gradiente a ciascun poligono nel set di dati, in base al valore dei dati del censimento. Puoi applicare uno stile ai dati utilizzando un oggetto Data.StyleOptions
o una funzione che restituisce un oggetto Data.StyleOptions
.
// set up the style rules and events for google.maps.Data map.data.setStyle(styleFeature); function styleFeature(feature) { var low = [5, 69, 54]; // color of smallest datum var high = [151, 83, 34]; // color of largest datum // delta represents where the value sits between the min and max var delta = (feature.getProperty('census_variable') - censusMin) / (censusMax - censusMin); var color = []; for (var i = 0; i < 3; i++) { // calculate an integer color based on the delta color[i] = (high[i] - low[i]) * delta + low[i]; } // determine whether to show this shape or not var showRow = true; if (feature.getProperty('census_variable') == null || isNaN(feature.getProperty('census_variable'))) { showRow = false; } var outlineWeight = 0.5, zIndex = 1; if (feature.getProperty('state') === 'hover') { outlineWeight = zIndex = 2; } return { strokeWeight: outlineWeight, strokeColor: '#fff', zIndex: zIndex, fillColor: 'hsl(' + color[0] + ',' + color[1] + '%,' + color[2] + '%)', fillOpacity: 0.75, visible: showRow }; }
Oltre a colorare i poligoni, il codice seguente crea un elemento interattivo aggiungendo eventi che rispondono all'attività del mouse. Passando il mouse sopra un poligono, viene evidenziato il bordo dello stato e, contemporaneamente, il controllo della casella dei dati viene aggiornato sulla mappa.
// set up the style rules and events for google.maps.Data map.data.addListener('mouseover', mouseInToRegion); map.data.addListener('mouseout', mouseOutOfRegion); /** * Responds to the mouse-in event on a map shape (state). * * @param {?google.maps.MapMouseEvent} e */ function mouseInToRegion(e) { // set the hover state so the setStyle function can change the border e.feature.setProperty('state', 'hover'); var percent = (e.feature.getProperty('census_variable') - censusMin) / (censusMax - censusMin) * 100; // update the label document.getElementById('data-label').textContent = e.feature.getProperty('NAME'); document.getElementById('data-value').textContent = e.feature.getProperty('census_variable').toLocaleString(); document.getElementById('data-box').style.display = 'block'; document.getElementById('data-caret').style.display = 'block'; document.getElementById('data-caret').style.paddingLeft = percent + '%'; } /** * Responds to the mouse-out event on a map shape (state). * * @param {?google.maps.MapMouseEvent} e */ function mouseOutOfRegion(e) { // reset the hover state, returning the border to normal e.feature.setProperty('state', 'normal'); }
Caricamento dei poligoni dei confini di stato
Aggiungi il codice seguente dopo l'intera funzione initMap
. La funzione loadMapShapes
carica i poligoni per i confini degli stati degli Stati Uniti da un file GeoJSON utilizzando il metodo loadGeoJson
.
/** Loads the state boundary polygons from a GeoJSON source. */ function loadMapShapes() { // load US state outline polygons from a GeoJSON file map.data.loadGeoJson('https://storage.googleapis.com/mapsdevsite/json/states.js', { idPropertyName: 'STATE' });
Aggiungi la riga seguente alla fine della funzione initMap
.
// state polygons only need to be loaded once, do them now loadMapShapes();
Se selezioni un'opzione di origine dati dal menu a discesa dei controlli della mappa, la mappa invia una query all'API US Census Data per trovare la variabile specificata. Per collegare i dati del censimento ai dati di forma, il codice imposta idPropertyName
su "STATE", che è una chiave comune sia nei dati del censimento che nelle proprietà GeoJson.
Maggiori informazioni
Questa demo utilizza l'API di dati di Census Bureau, ma non è approvata o certificata dal Census Bureau.