jHC

Description

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

Additional Features

Besides n-dimensional data, the algorithm also works on data points given by _GPS coordinates_.

Usage

1. Import the script.

``html

`

2. Sample Data Format

$3

`javascript
let point_data = [
[0.1, 5],
[2, 4],
[0, 7]
];
`

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The latitude is the first number in the pair followed by the longitude.

`javascript
let gps_point_data = [
[55.7858667, 12.5233995],
[45.4238667, 12.5233995],
[25.3438667, 11.6533995]
];
`

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();
`

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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.

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See working example in the example/example.html file. Use the console to inspect the input and output of the algorithm.