iir_filt: Butterworth IIR filter

In craddm/eegUtils: Utilities for Electroencephalographic (EEG) Analysis

Butterworth IIR filter

Description

Construct a Butterworth IIR filter and filter input data. This uses signal::filt_filt, which filters the signal twice to - once forwards, then again backwards).

Usage

iir_filt(data, ...)

## S3 method for class 'data.frame'
iir_filt(
  data,
  low_freq = NULL,
  high_freq = NULL,
  filter_order = 4,
  srate,
  silent = FALSE,
  ...
)

## S3 method for class 'eeg_data'
iir_filt(
  data,
  low_freq = NULL,
  high_freq = NULL,
  filter_order = 4,
  silent = FALSE,
  ...
)

## S3 method for class 'eeg_epochs'
iir_filt(
  data,
  low_freq = NULL,
  high_freq = NULL,
  filter_order = 4,
  silent = FALSE,
  ...
)

Arguments

data	Data to be filtered.
...	Parameters passed to S3 methods
low_freq	Low passband edge.
high_freq	High passband edge.
filter_order	Order of the Butterworth filter.
srate	Sampling rate of the signal.
silent	Turns off filtering messages.

Details

low_freq and high_freq are passband edges. Pass low freq or high freq alone to perform high-pass or low-pass filtering respectively. For band-pass or band-stop filters, pass both low_freq and high_freq.

If low_freq < high_freq, bandpass filtering is performed.

If low_freq > high_freq, bandstop filtering is performed.

Note that the signal is first zero-meaned using either channel means or by-channel epoch means.

Methods (by class)

• data.frame: Filter a data frame

• eeg_data: Filter eeg_data objects

• eeg_epochs: Filter eeg_epochs objects.

Author(s)

Matt Craddock [e-mail]

Examples

plot_psd(iir_filt(demo_epochs, low_freq = 1, high_freq = 30))
plot_psd(iir_filt(demo_epochs, low_freq = 12, high_freq = 8))

craddm/eegUtils documentation built on March 24, 2022, 9:17 a.m.