downsample-lttb

Largest Triangle Three Buckets downsample algorithm by Sveinn Steinarsson reshaped into a node.js module.

This is useful for downsampling large dataseries in order to be able to plot a representative chart shape with a manageable amount of data points.

Instructions

Install with

npm install git+https://github.com/pingec/downsample-lttb.git

Usage example

var downsampler = require("downsample-lttb");

//provide a series as an array of [x,y] pairs
var dummyDataSeries = [[1,2],[2,2],[3,3],[4,3],[5,6],[6,3],[7,3],[8,5],[9,4],[10,4],[11,1],[12,2]];

//pass the series and number of desired datapoints
var downsampledSeries = downsampler.processData(dummyDataSeries, 3);

console.log(downsampledSeries);	
//outputs [ [ 1, 2 ], [ 5, 6 ], [ 12, 2 ] ]

Downsampled chart series examples

# of samples: 8614 downsampled to: 500

# of samples: 8614 downsampled to: 200

# of samples: 8614 downsampled to: 100

# of samples: 8614 downsampled to: 50