syncopy.specest.wavelet.wavelet¶

syncopy.specest.wavelet.wavelet(trl_dat, preselect, postselect, padbegin, padend, samplerate=None, toi=None, scales=None, timeAxis=0, wav=None, polyremoval=None, output_fmt='pow', noCompute=False, chunkShape=None)[source]¶

Perform time-frequency analysis on multi-channel time series data using a wavelet transform

Parameters

trl_dat (2D numpy.ndarray) – Uniformly sampled multi-channel time-series
preselect (slice) – Begin- to end-samples to perform analysis on (trim data to interval). See Notes for details.
postselect (list of slices or list of 1D NumPy arrays) – Actual time-points of interest within interval defined by preselect See Notes for details.
padbegin (int) – Number of samples to pre-pend to trl_dat
padend (int) – Number of samples to append to trl_dat
samplerate (float) – Samplerate of trl_dat in Hz
toi (1D numpy.ndarray or str) – Either time-points to center wavelets on if toi is a numpy.ndarray, or “all” to center wavelets on all samples in trl_dat. Please refer to freqanalysis() for further details. Note: The value of toi has to agree with provided padding values. See Notes for more information.
scales (1D numpy.ndarray) – Set of scales to use in wavelet transform.
timeAxis (int) – Index of running time axis in trl_dat (0 or 1)
wav (callable) – Wavelet function to use, one of availableWavelets
polyremoval (int) – FIXME: Not implemented yet Order of polynomial used for de-trending. A value of 0 corresponds to subtracting the mean (“de-meaning”), polyremoval = 1 removes linear trends (subtracting the least squares fit of a linear function), polyremoval = N for N > 1 subtracts a polynomial of order N (N = 2 quadratic, N = 3 cubic etc.). If polyremoval is None, no de-trending is performed.
output_fmt (str) – Output of spectral estimation; one of availableOutputs
noCompute (bool) – Preprocessing flag. If True, do not perform actual calculation but instead return expected shape and numpy.dtype of output array.
chunkShape (None or tuple) – If not None, represents shape of output object spec (respecting provided values of scales, preselect, postselect etc.)

Returns

spec – Complex or real time-frequency representation of (padded) input data.

Return type

numpy.ndarray

Notes

This method is intended to be used as computeFunction() inside a ComputationalRoutine. Thus, input parameters are presumed to be forwarded from a parent metafunction. Consequently, this function does not perform any error checking and operates under the assumption that all inputs have been externally validated and cross-checked.

For wavelets, data concatenation is performed by first trimming trl_dat to an interval of interest (via preselect), then performing the actual wavelet transform, and subsequently extracting the actually wanted time-points (via postselect).