Align multiple PhysioExperiment objects to a common sampling rate

Takes two or more named PhysioExperiment objects and resamples them so they all share a single sampling rate, then wraps the result in a MultiPhysioExperiment.

Usage

alignSignals(
  ...,
  method = c("lowest_rate", "common_rate", "resample", "elastic"),
  target_rate = NULL
)

Arguments

...

Named PhysioExperiment objects.

method

Character: one of "lowest_rate" (default), "common_rate", "resample", or "elastic".

target_rate

Numeric scalar: required when method = "resample".

Value

A MultiPhysioExperiment containing the (possibly resampled) input objects.

Details

Three alignment strategies are available:

"lowest_rate"

(default) Resample all signals to the lowest sampling rate present.

"common_rate"

Resample all signals to the highest sampling rate present.

"resample"

Resample all signals to the rate given by target_rate (which must be supplied).

"elastic"

Resample to the lowest rate, then additionally apply an elastic (SRVF) time warping of every object onto the first, so that shared events line up in phase. The warping is computed from each object's first channel and carried to all its channels; it is stored in metadata()$elastic_warp. Objects whose duration differs from the reference after rate alignment are left un-warped. See elasticAlign().

If every input already shares the same sampling rate, no resampling is performed regardless of the chosen method (elastic warping, if requested, is still applied).

See also

alignToRate(), mergePhysio(), MultiPhysioExperiment(), couplingAnalysis()

Examples

eeg <- PhysioExperiment(
  assays = list(raw = matrix(rnorm(500 * 2), nrow = 500)),
  samplingRate = 500
)
emg <- PhysioExperiment(
  assays = list(raw = matrix(rnorm(1000 * 2), nrow = 1000)),
  samplingRate = 1000
)
mpe <- alignSignals(EEG = eeg, EMG = emg, method = "lowest_rate")