modalities.fmri.realfuncs¶
Module: modalities.fmri.realfuncs¶
Helper functions for constructing design regressors
Functions¶
- nipy.modalities.fmri.realfuncs.dct_ii_basis(volume_times, order=None, normcols=False)¶
DCT II basis up to order order
See: https://en.wikipedia.org/wiki/Discrete_cosine_transform#DCT-II
By default, basis not normalized to length 1, and therefore, basis is not orthogonal. Normalize basis with normcols keyword argument.
- Parameters:
- volume_timesarray-like
Times of acquisition of each volume. Must be regular and continuous otherwise we raise an error.
- orderNone or int, optional
Order of DCT-II basis. If None, return full basis set.
- normcolsbool, optional
If True, normalize columns to length 1, so return orthogonal dct_basis.
- Returns:
- dct_basisarray
Shape
(len(volume_times), order)array with DCT-II basis up to order order.
- Raises:
- ValueError
If difference between successive volume_times values is not constant over the 1D array.
- nipy.modalities.fmri.realfuncs.dct_ii_cut_basis(volume_times, cut_period)¶
DCT-II regressors with periods >= cut_period
See: http://en.wikipedia.org/wiki/Discrete_cosine_transform#DCT-II
- Parameters:
- volume_timesarray-like
Times of acquisition of each volume. Must be regular and continuous otherwise we raise an error.
- cut_period: float
Cut period (wavelength) of the low-pass filter (in time units).
- Returns:
- cdrift: array shape (n_scans, n_drifts)
DCT-II drifts plus a constant regressor in the final column. Constant regressor always present, regardless of cut_period.