jhcluster
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Hierarchical clustering algorithm
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Hierarchical clustering **(agglomerative)** is a clustering algorithm that builds a cluster hierarchy from some given points **[1]**.
**[1]** http://en.wikipedia.org/wiki/Hierarchical_clustering
Besides n-dimensional data, the algorithm also works on data points given by **_GPS coordinates_**.
1. Import the script.
```html
<script type="text/javascript" src="jHC.js"></script>
```
2. Sample Data Format
```javascript
let point_data = [
[],
[],
[]
];
```
The **latitude** is the first number in the pair followed by the **longitude**.
```javascript
let gps_point_data = [
[],
[],
[]
];
```
3. Run the algorithm. To run the algorithm you need to provide the data along with the **linkage** and **distance** parameters. For the traditional **hierarchical clustering** the steps are the following:
```javascript
let hc = jHC()
.linkage('AVERAGE')
.distance('EUCLIDEAN')
.data(point_data);
```
The distance functions available are: **'EUCLIDEAN', 'HAVERSINE'** (for GPS data), **'MANHATTAN'**. The linkages implemented are **'AVERAGE', 'COMPLETE'** and **'SINGLE'**. Additionally you can provide your own distance function, which must accept at least two parameters (the two points), and then pass it to the _distance_ method as its parameter. The next step is to simply run the clustering algorithm.
```javascript
// This will run the aglorithm and return the resulting hierarchy tree.
let hierarchy_tree = hc();
```
The end root node is wrapped in an array and returned. The resulting clustering hierarchy has the following format:
```javascript
[
{
children: [
// the two children of the root hierarchy node.
{
children: [
{
//leaf node
coordinates: [9, 5],
name: 1,
size: 1
},
{
//leaf node
coordinates: [7, 9],
name: 2,
size: 1
}
],
coordinates: [11, 12],
name: 3,
size: 2
},
{
//leaf node
coordinates: [9, 9],
name: 0,
size: 1
}
],
coordinates: [13, 14], // centroid coordinates for the cluster
name: 4, // id of cluster
size: 3 // number of points contained
}
];
```
Additionally you can get the leaf nodes with the _leafNodes_ function.
See working example in the **example/example.html** file. Use the console to inspect the input and output of the algorithm.