pwelch: Calculate 'Welch Periodogram'

In ravetools: Signal and Image Processing Toolbox for Analyzing Intracranial Electroencephalography Data

Calculate 'Welch Periodogram'

Description

pwelch is for single signal trace only; mv_pwelch is for multiple traces. Currently mv_pwelch is experimental and should not be called directly.

Usage

pwelch(
  x,
  fs,
  window = 64,
  noverlap = window/2,
  nfft = "auto",
  window_family = hamming,
  col = "black",
  xlim = NULL,
  ylim = NULL,
  main = "Welch periodogram",
  plot = 0,
  log = c("xy", "", "x", "y"),
  ...
)

## S3 method for class ''ravetools-pwelch''
print(x, ...)

## S3 method for class ''ravetools-pwelch''
plot(
  x,
  log = c("xy", "x", "y", ""),
  se = FALSE,
  xticks,
  type = "l",
  add = FALSE,
  col = graphics::par("fg"),
  col.se = "orange",
  alpha.se = 0.5,
  lty = 1,
  lwd = 1,
  cex = 1,
  las = 1,
  main = "Welch periodogram",
  xlab,
  ylab,
  xlim = NULL,
  ylim = NULL,
  xaxs = "i",
  yaxs = "i",
  xline = 1.2 * cex,
  yline = 2 * cex,
  mar = c(2.6, 3.8, 2.1, 0.6) * (0.5 + cex/2),
  mgp = cex * c(2, 0.5, 0),
  tck = -0.02 * cex,
  grid = TRUE,
  ...
)

mv_pwelch(
  x,
  margin,
  fs,
  window = 64,
  noverlap = window/2,
  nfft = "auto",
  window_family = hamming
)

Arguments

x	numerical vector or a row-major vector, signals. If x is a matrix, then each row is a channel. For plot function, x is the instance returned by pwelch function.
fs	sample rate, average number of time points per second
window	window length in time points, default size is 64
noverlap	overlap between two adjacent windows, measured in time points; default is half of the window
nfft	number of points in window function; default is automatically determined from input data and window, scaled up to the nearest power of 2
window_family	function generator for generating filter windows, default is hamming. This can be any window function listed in the filter window family, or any window generator function from package gsignal. Default is hamming. For 'iEEG' users, both hamming and blackmanharris are offered by 'EEG-lab'; while blackmanharris offers better attenuation than Hamming windows, it also has lower spectral resolution. hamming has a 42.5 dB side-lobe attenuation. This may mask spectral content below this value (relative to the peak spectral content). Choosing different windows enables you to make trade-off between resolution (e.g., using a rectangular window) and side-lobe attenuation (e.g., using a hanning window)
col, xlim, ylim, main, type, cex, las, xlab, ylab, lty, lwd, xaxs, yaxs, mar, mgp, tck	parameters passed to plot.default
plot	integer, whether to plot the result or not; choices are 0, no plot; 1 plot on a new canvas; 2 add to existing canvas
log	indicates which axis should be log10-transformed, used by the plot function. For 'x' axis, it's log10-transform; for 'y' axis, it's 10log10-transform (decibel unit). Choices are "xy", "x", "y", and "".
...	will be passed to plot.pwelch or ignored
se	logical or a positive number indicating whether to plot standard error of mean; default is false. If provided with a number, then a multiple of standard error will be drawn. This option is only available when power is in log-scale (decibel unit)
xticks	ticks to show on frequency axis
add	logical, whether the plot should be added to existing canvas
col.se, alpha.se	controls the color and opacity of the standard error
xline, yline	controls how close the axis labels to the corresponding axes
grid	whether to draw rectangular grid lines to the plot; only respected when add=FALSE; default is true
margin	the margin in which pwelch should be applied to

Value

A list with class 'ravetools-pwelch' that contains the following items:

freq

frequencies used to calculate the 'periodogram'

spec

resulting spectral power for each frequency

window

window function (in numerical vector) used

noverlap

number of overlapping time-points between two adjacent windows

nfft

number of basis functions

fs

sample rate

x_len

input signal length

method

a character string 'Welch'

Examples

x <- rnorm(1000)
pwel <- pwelch(x, 100)
pwel

plot(pwel, log = "xy")

ravetools documentation built on Sept. 11, 2024, 9:06 p.m.