butterFilter {NADfinder} | R Documentation

## Low pass filter on ratios by butterworth filter

### Description

The Butterworth filter is a type of signal processing filter designed to have as flat a frequency response as possible in the passband.

### Usage

    butterFilter(ratios, N = ceiling(length(ratios)/200))

### Arguments

`ratios` | A vector of numeric. It is log2-transformed ratios, CPMRatios or OddRatios in each window.
`N` | numeric(1) or integer(1). Critical frequencies of the low pass filter will be set as 1/N. 1/N is a cutoff at 1/N-th of the Nyquist frequency. By default, it is suppose there are about 200 peaks in the inputs.

### Value

A vector of numeric with same length of input ratios. The vector indicates smoothed ratios.

### Examples

    ratios <- runif(20000)
    butterFilter(ratios)

[Package NADfinder version 1.8.1 Index]