# @yandex/ymaps3-clusterer package

---

Using the clusterer helps to display a large number of markers on the map.
When the scale of the map is increased, individual markers are combined into a cluster;
when the map is scaled down, the cluster breaks up into individual markers.

[![npm version](https://badge.fury.io/js/@yandex%2Fymaps3-clusterer.svg)](https://www.npmjs.com/package/@yandex/ymaps3-clusterer)
[![npm](https://img.shields.io/npm/dm/@yandex/ymaps3-clusterer.svg)](https://www.npmjs.com/package/@yandex/ymaps3-clusterer)

## How use

The package is located in the `dist` folder:

- `dist/types` TypeScript types
- `dist/esm` es6 modules for direct connection in your project
- `dist/index.js` Yandex JS Module

Recommended use `@yandex/ymaps3-clusterer` as usual npm package.

### Usage with npm

Install `@yandex/ymaps3-clusterer` package from npm:

```sh
npm install @yandex/ymaps3-clusterer
```

The JS API is loaded dynamically, so the package must be used after the main JS API has loaded:

```js
await ymaps3.ready; // waiting for the main JS API to load.

// ...

const {YMapClusterer} = await import('@yandex/ymaps3-clusterer');

// ...

map.addChild(new YMapClusterer(props));
```

### Usage without npm

You can use CDN with module loading handler in JS API on your page.

By default `ymaps3.import` can load self modules.
Just use `ymaps3.registerCdn` and `ymaps3.import`:

```js
// register in `ymaps3.import` which CDN to take the package from
ymaps3.import.registerCdn('https://cdn.jsdelivr.net/npm/{package}', '@yandex/ymaps3-clusterer@latest');

// ...

// import package from CDN
const {YMapClusterer} = await ymaps3.import('@yandex/ymaps3-clusterer');
```

## Working with the package

We will use these functions and constants in example:

```js
const LOCATION = {center: [55.205247, 25.077816], zoom: 10};

const BOUNDS = [
  [54.58311, 25.9985],
  [56.30248, 24.47889]
];

const rndPoint = (bounds) => [
  bounds[0][0] + (bounds[1][0] - bounds[0][0]) * Math.random(),
  bounds[1][1] + (bounds[0][1] - bounds[1][1]) * Math.random()
];

/**
 * Generates randomly count points inside the BOUNDS area
 *
 * @param count
 * @param bounds
 * @returns {{geometry: {coordinates: *}, id, type: string, properties: {name: string}}[]}
 */
const getRandomPoints = (count, bounds) =>
  Array.from({length: count}, () => ({
    type: 'Feature',
    id: i++,
    geometry: {coordinates: rndPoint(bounds)},
    properties: {name: 'beer shop'}
  }));
```

```js
main();
async function main() {
  await ymaps3.ready;
  const {YMap, YMapDefaultSchemeLayer, YMapLayer, YMapFeatureDataSource} = ymaps3;

  const {YMapClusterer, clusterByGrid} = await ymaps3.import('@yandex/ymaps3-clusterer');

  map = new YMap(document.getElementById('app'), {location: LOCATION});
  map
    .addChild(new YMapDefaultSchemeLayer())
    .addChild(new YMapFeatureDataSource({id: 'clusterer-source'}))
    .addChild(new YMapLayer({source: 'clusterer-source', type: 'markers', zIndex: 1800}));

  const contentPin = document.createElement('div');
  contentPin.innerHTML = '<img src="./pin.svg" class="pin">';

  // Makes usual point Marker
  const marker = (feature) =>
    new ymaps3.YMapMarker(
      {
        coordinates: feature.geometry.coordinates,
        source: 'clusterer-source'
      },
      contentPin.cloneNode(true)
    );

  // Makes Cluster Marker
  const cluster = (coordinates, features) =>
    new ymaps3.YMapMarker(
      {
        coordinates,
        source: 'clusterer-source'
      },
      circle(features.length).cloneNode(true)
    );

  function circle(count) {
    const circle = document.createElement('div');
    circle.classList.add('circle');
    circle.innerHTML = `
        <div class="circle-content">
            <span class="circle-text">${count}</span>
        </div>
    `;
    return circle;
  }

  const clusterer = new YMapClusterer({
    method: clusterByGrid({gridSize: 64}),
    features: getRandomPoints(100, BOUNDS),
    marker,
    cluster
  });

  map.addChild(clusterer);
}
```

Or React version

```jsx
main();
async function main() {
  const [ymaps3React] = await Promise.all([ymaps3.import('@yandex/ymaps3-reactify'), ymaps3.ready]);
  const reactify = ymaps3React.reactify.bindTo(React, ReactDOM);
  const {YMap, YMapDefaultSchemeLayer, YMapLayer, YMapFeatureDataSource, YMapMarker} = reactify.module(ymaps3);

  const {YMapClusterer, clusterByGrid} = reactify.module(await ymaps3.import('@yandex/ymaps3-clusterer'));
  const {useState, useCallback, useMemo} = React;
  const points = getRandomPoints(100, BOUNDS);
  const gridSizedMethod = clusterByGrid({gridSize: 64});

  function App() {
    const marker = useCallback(
      (feature) => (
        <YMapMarker key={feature.id} coordinates={feature.geometry.coordinates} source="clusterer-source">
          <img src="./pin.svg" className="pin" />
        </YMapMarker>
      ),
      []
    );

    const cluster = useCallback(
      (coordinates, features) => (
        <YMapMarker key={`${features[0].id}-${features.length}`} coordinates={coordinates} source="clusterer-source">
          <div className="circle">
            <div className="circle-content">
              <span className="circle-text">{features.length}</span>
            </div>
          </div>
        </YMapMarker>
      ),
      []
    );

    return (
      <>
        <YMap location={LOCATION} ref={(x) => (map = x)}>
          <YMapDefaultSchemeLayer />
          <YMapFeatureDataSource id="clusterer-source" />
          <YMapLayer source="clusterer-source" type="markers" zIndex={1800} />
          <YMapClusterer marker={marker} cluster={cluster} method={gridSizedMethod} features={points} />
        </YMap>
      </>
    );
  }

  const reactRoot = ReactDOM.createRoot(document.getElementById('app'));
  reactRoot.render(
    <React.StrictMode>
      <App />
    </React.StrictMode>
  );
}
```

## More about working with the package

### Example 1: Creating a Map and adding a Clusterer to the Map

We declare a variable for the map, load the ymaps3 library, extract the necessary classes.

```javascript
window.map = null;
async function main() {
  await ymaps3.ready;

  const {YMap, YMapDefaultSchemeLayer, YMapMarker, YMapLayer, YMapFeatureDataSource} = ymaps3;
  //...
}
```

We load the package with the clusterer, extract the classes for creating clusterer objects and the clustering method.

```javascript
const {YMapClusterer, clusterByGrid} = await ymaps3.import('@yandex/ymaps3-clusterer');
```

Create and add to the map a layer with a default schema, data sources, a layer of markers.

```javascript
const map = new YMap(document.getElementById('app'), {location: LOCATION});
map
  .addChild(new YMapDefaultSchemeLayer())
  .addChild(new YMapFeatureDataSource({id: 'my-source'}))
  .addChild(new YMapLayer({source: 'my-source', type: 'markers', zIndex: 1800}));
```

You can set any markup for the marker and for the cluster.

```javascript
const contentPin = document.createElement('div');
contentPin.innerHTML = '<img src="./pin.svg" />';
```

We declare the function for rendering ordinary markers, we will submit it to the clusterer settings.
Note that the function must return any Entity element. In the example, this is ymaps3.YMapMarker.

```javascript
const marker = (feature) =>
  new ymaps3.YMapMarker(
    {
      coordinates: feature.geometry.coordinates,
      source: 'my-source'
    },
    contentPin.cloneNode(true)
  );
```

As for ordinary markers, we declare a cluster rendering function that also returns an Entity element.

```javascript
const cluster = (coordinates, features) =>
  new ymaps3.YMapMarker(
    {
      coordinates,
      source: 'my-source'
    },
    circle(features.length).cloneNode(true)
  );

function circle(count) {
  const circle = document.createElement('div');
  circle.classList.add('circle');
  circle.innerHTML = `
        <div class="circle-content">
            <span class="circle-text">${count}</span>
        </div>
    `;
  return circle;
}
```

Let's declare an array with marker coordinates, then create an array of features with the appropriate interface. We will pass it to the clusterer settings.

```javascript
const coordinates = [
  [54.64, 25.76],
  [54.63, 25.7],
  [54.43, 25.69],
  [54.42, 25.127],
  [54.12, 25.437]
];

const points = coordinates.map((lnglat, i) => ({
  type: 'Feature',
  id: i,
  geometry: {coordinates: lnglat},
  properties: {name: 'Point of issue of orders'}
}));
```

We create a clusterer object and add it to the map object.
As parameters, we pass the clustering method, an array of features, the functions for rendering markers and clusters.
For the clustering method, we will pass the size of the grid division in pixels.

```javascript
const clusterer = new YMapClusterer({
  method: clusterByGrid({gridSize: 64}),
  features: points,
  marker,
  cluster
});

map.addChild(clusterer);
```

### Example 2. Using a Clusterer with React JS

We declare a variable for the map, load the ymaps3 library, extract the necessary classes.

```jsx
window.map = null;
main();
async function main() {
  await ymaps3.ready;
  const ymaps3React = await ymaps3.import('@yandex/ymaps3-reactify');
  const reactify = ymaps3React.reactify.bindTo(React, ReactDOM);
  const {YMap, YMapDefaultSchemeLayer, YMapLayer, YMapFeatureDataSource, YMapMarker} = reactify.module(ymaps3);
  // ...
}
```

We connect the package with the clusterer, extract the classes for creating clusterer objects and the clustering method.

```jsx
const {YMapClusterer, clusterByGrid} = reactify.module(await ymaps3.import('@yandex/ymaps3-clusterer'));
```

We extract the necessary hooks. Let's declare an array with marker coordinates, then create an array of features with the appropriate interface.
We will pass it to the clusterer settings.

```jsx
const {useCallback, useMemo} = React;

const coordinates = [
  [54.64, 25.76],
  [54.63, 25.7],
  [54.43, 25.69],
  [54.47, 25.68],
  [54.53, 25.6],
  [54.59, 25.71],
  [54.5, 25.63],
  [54.42, 25.57],
  [54.12, 25.57],
  [54.32, 25.57]
];

const points = coordinates.map((lnglat, i) => ({
  type: 'Feature',
  id: i,
  geometry: {coordinates: lnglat},
  properties: {name: 'Point of issue of orders'}
}));
```

We declare a render function. For the clustering method, we pass and store the size of one grid division in pixels.

```jsx
function App() {
  const gridSizedMethod = useMemo(() => clusterByGrid({gridSize: 64}), []);
  // ...
}
```

We declare a function for rendering ordinary markers. Note that the function must return any Entity element. In the example, this is ymaps3.YMapMarker.

```jsx
const marker = useCallback(
  (feature) => (
    <YMapMarker coordinates={feature.geometry.coordinates} source={'my-source'}>
      <img src={'./pin.svg'} />
    </YMapMarker>
  ),
  []
);
```

We declare a cluster rendering function that also returns an Entity element. We will transfer the marker and cluster rendering functions to the clusterer settings.

```jsx
const cluster = useCallback(
  (coordinates, features) => (
    <YMapMarker coordinates={coordinates} source={'my-source'}>
      <div className="circle">
        <div className="circle-content">
          <span className="circle-text">{features.length}</span>
        </div>
      </div>
    </YMapMarker>
  ),
  []
);
```

We return JSX, in which we render the components of the map, the default layer, data sources, the layer for markers and the clusterer.
In the clusterer props, we pass the previously declared functions for rendering markers and clusters, the clustering method, and an array of features.

```jsx
function App() {
  // ...
  return (
    <>
      <YMap location={LOCATION} ref={(x) => (map = x)}>
        <YMapDefaultSchemeLayer />
        <YMapFeatureDataSource id="my-source" />
        <YMapLayer source="my-source" type="markers" zIndex={1800} />
        <YMapClusterer marker={marker} cluster={cluster} method={gridSizedMethod} features={points} />
      </YMap>
    </>
  );
}
// ...
ReactDOM.render(<App />, document.getElementById('app'));
```