Plot Power Spectral Density

Source: R/frequency_plotting.R

Calculate and plot the PSD for eeg_* objects. Output units are dB. The PSD is calculated using Welch's method.

plot_psd(data, freq_range = NULL, ...)

# S3 method for class 'eeg_epochs'
plot_psd(
  data,
  freq_range = NULL,
  n_fft = 256,
  seg_length = NULL,
  noverlap = NULL,
  demean = TRUE,
  keep_trials = TRUE,
  ...
)

# S3 method for class 'eeg_data'
plot_psd(
  data,
  freq_range = NULL,
  n_fft = 2048,
  noverlap = NULL,
  seg_length = NULL,
  ...
)

# S3 method for class 'eeg_ICA'
plot_psd(
  data,
  freq_range = NULL,
  components = NULL,
  seg_length = NULL,
  noverlap = NULL,
  n_fft = 256,
  ...
)

# S3 method for class 'data.frame'
plot_psd(data, freq_range = NULL, ...)

# S3 method for class 'eeg_evoked'
plot_psd(
  data,
  freq_range = NULL,
  n_fft = 256,
  seg_length = NULL,
  noverlap = NULL,
  keep_trials = TRUE,
  ...
)

# S3 method for class 'eeg_group'
plot_psd(
  data,
  freq_range = NULL,
  n_fft = 256,
  seg_length = NULL,
  noverlap = NULL,
  demean = TRUE,
  ...
)

Arguments

data

Object of class eeg_epochs, eeg_data, or eeg_ICA.

freq_range

Vector of lower and upper frequencies to plot. (e.g. c(1, 40))

...

Additional parameters.

n_fft

Number of points to use for the underlying FFTs. Defaults to 256 for eeg_epochs or minimum of 2048 or the signal length for eeg_data.

seg_length

Length of individual segments. Defaults to n_fft. Must be <= n_fft.

noverlap

Amount of overlap between segments, in sampling points. Defaults to 50%.

demean

Remove epoch means before FFT.

keep_trials

Whether to keep trial information in the output or average over all trials

components

Which components to compute the PSD for. Defaults to all.

Value

A ggplot object.

Details

Welch's method splits the data into multiple segments and then averages over those segments. For epoched data, Welch's FFT is calculated separately for each trial.

Specific parameters such as the number of FFT points and the amount of overlap between segments can be passed to Welch's FFT.

Methods (by class)

  • plot_psd(eeg_epochs): Plot PSD for eeg_epochs.

  • plot_psd(eeg_data): Plot PSD for eeg_data.

  • plot_psd(eeg_ICA): Plot PSD for eeg_ICA objects

  • plot_psd(data.frame): Plot PSD for data.frames.

  • plot_psd(eeg_evoked): Plot PSD for eeg_evoked objects

  • plot_psd(eeg_group): Plot PSD for eeg_group objects is not currently supported

Author

Matt Craddock, matt@mattcraddock.com

Examples

 plot_psd(demo_epochs)
#> Removing channel means per epoch...
#> Computing Power Spectral Density using Welch's method.
#> FFT length: 256
#> Segment length: 84
#> Overlapping points: 42 (50% overlap)

 plot_psd(demo_epochs, seg_length = 256)
#> Removing channel means per epoch...
#> Computing Power Spectral Density using Welch's method.
#> FFT length: 256
#> Segment length: 84
#> Overlapping points: 42 (50% overlap)