filters

This module implements 1D noise reduction filters. There are currently two available:

• median filter

• rolling average with threshold

median

median(data, windowSize)

• data: An array of numbers.

• windowSize: The size of the window over which the median is applied. Should be an odd number greater than one, defaults to 3.

Example

var median = require('filters').median;
var raw = [ 2, 3, 4, 9, 6, 2 ];
console.log(median(raw));
// => [ 2, 3, 4, 6, 6, 2 ]

average

average(data, windowSize, threshold)

• data: An array of numbers.

• windowSize: The size of the rolling average window. Should be two or greater, defaults to 3.

• threshold: Maximum difference between two numbers for the average still to be applied. Use this to smooth out small variations but large varitions through immediately. The difference between /a/ and /b/ is calculated as /(max(a, b) - min(a, b)) / max(a, b)/. No default.

Example

var median = require('filters').average;
var raw = [ 2, 3, 4, 9, 6, 2 ];
console.log(average(raw, 3, 0.5));
// => [ 2, 2.5, 3, 9, 7.5, 2 ]

License

MIT