Calculate power baseline

Usage

power_baseline(
  x,
  baseline_windows,
  method = c("percentage", "sqrt_percentage", "decibel", "zscore", "sqrt_zscore"),
  units = c("Trial", "Frequency", "Electrode"),
  ...
)

# S3 method for class 'rave_prepare_power'
power_baseline(
  x,
  baseline_windows,
  method = c("percentage", "sqrt_percentage", "decibel", "zscore", "sqrt_zscore"),
  units = c("Frequency", "Trial", "Electrode"),
  electrodes,
  ...
)

# S3 method for class 'FileArray'
power_baseline(
  x,
  baseline_windows,
  method = c("percentage", "sqrt_percentage", "decibel", "zscore", "sqrt_zscore"),
  units = c("Frequency", "Trial", "Electrode"),
  filebase = NULL,
  ...
)

# S3 method for class 'array'
power_baseline(
  x,
  baseline_windows,
  method = c("percentage", "sqrt_percentage", "decibel", "zscore", "sqrt_zscore"),
  units = c("Trial", "Frequency", "Electrode"),
  ...
)

Arguments

x: R array, filearray, or 'rave_prepare_power' object created by prepare_subject_power_with_epochs.
baseline_windows: list of baseline window (intervals)
method: baseline method; choices are 'percentage', 'sqrt_percentage', 'decibel', 'zscore', 'sqrt_zscore'; see 'Details' in baseline_array
units: the unit of the baseline; see 'Details'
...: passed to other methods
electrodes: the electrodes to be included in baseline calculation; for power repository object produced by prepare_subject_power_with_epochs only; default is all available electrodes
filebase: where to store the output; default is NULL and is automatically determined

Value

Usually the same type as the input: for arrays and filearray, the outputs are also the same type with the same dimensions; for 'rave_prepare_power' repositories, the results will be stored in its 'baselined' element; see 'Examples'.

Details

The arrays must be four-mode tensor and must have valid named dimnames. The dimension names must be 'Trial', 'Frequency', 'Time', 'Electrode', case sensitive.

The baseline_windows determines the baseline windows that are used to calculate time-points of baseline to be included. This can be one or more intervals and must pass the validation function validate_time_window.

The units determines the unit of the baseline. It can be one or more of 'Trial', 'Frequency', 'Electrode'. The default value is all of them, i.e., baseline for each combination of trial, frequency, and electrode. To share the baseline across trials, please remove 'Trial' from units. To calculate baseline that should be shared across electrodes (e.g. in some mini-electrodes), remove 'Electrode' from the units.

Examples


if( has_rave_subject("demo/DemoSubject") ) {

# The following code need to download additional demo data
# Please see https://rave.wiki/ for more details

repo <- prepare_subject_power_with_epochs(
  subject = "demo/DemoSubject",
  time_windows = c(-1, 3),
  electrodes = c(14, 15))

##### Direct baseline on the repository
power_baseline(x = repo, method = "decibel",
               baseline_windows = list(c(-1, 0), c(2, 3)))
power_mean <- repo$power$baselined$collapse(
  keep = c(2,1), method = "mean")
image(power_mean, x = repo$time_points, y = repo$frequency,
      xlab = "Time (s)", ylab = "Frequency (Hz)",
      main = "Mean power over trial (Baseline: -1~0 & 2~3)")
abline(v = 0, lty = 2, col = 'blue')
text(x = 0, y = 20, "Aud-Onset", col = "blue", cex = 0.6)

##### Alternatively, baseline on electrode instances
baselined <- lapply(repo$power$data_list, function(inst) {
  re <- power_baseline(inst, method = "decibel",
                       baseline_windows = list(c(-1, 0), c(2, 3)))
  collapse2(re, keep = c(2,1), method = "mean")
})
power_mean2 <- (baselined[[1]] + baselined[[2]]) / 2

# Same with precision difference
max(abs(power_mean2 - power_mean)) < 1e-6


}