def gauss_cop_pac(pha, amp):
"""Tensor-based Gaussian Copula PAC (gcPac).
This function assumes that phases and amplitudes have already been
prepared i.e. phases should be represented in a unit circle
(np.c_[np.sin(pha), np.cos(pha)]) and both inputs should also have been
copnormed.
Parameters
----------
pha, amp : array_like
Respectively the arrays of phases of shape (n_pha, ..., n_times) and
the array of amplitudes of shape (n_amp, ..., n_times).
Returns
-------
pac : array_like
Array of phase amplitude coupling of shape (n_amp, n_pha, ...)
References
----------
Ince et al 2017. :cite:`ince2017statistical`
"""
# prepare the shape of gcpac
n_pha, n_amp = pha.shape[0], amp.shape[0]
pha_sh = list(pha.shape[:-2])
gc = np.zeros([n_amp] + pha_sh, dtype=float)
# compute mutual information
for p in range(n_pha):
for a in range(n_amp):
gc[a, p, ...] = nd_mi_gg(pha[p, ...], amp[a, ...])
return gc
def gcpac(pha, amp):
"""Gaussian Copula Phase-amplitude coupling.
This function assumes that phases and amplitudes have already been
prepared i.e. phases should be represented in a unit circle
(np.c_[np.sin(pha), np.cos(pha)]) and both inputs should also have been
copnormed.
Parameters
----------
pha, amp : array_like
Respectively the arrays of phases of shape (n_pha, ..., n_times) and
the array of amplitudes of shape (n_amp, ..., n_times).
Returns
-------
pac : array_like
Array of phase amplitude coupling of shape (n_amp, n_pha, ...)
References
----------
Ince RAA, Giordano BL, Kayser C, Rousselet GA, Gross J, Schyns PG (2017) A
statistical framework for neuroimaging data analysis based on mutual
information estimated via a gaussian copula: Gaussian Copula Mutual
Information. Human Brain Mapping 38:1541–1573.
"""
# prepare the shape of gcpac
n_pha, n_amp = pha.shape[0], amp.shape[0]
pha_sh = list(pha.shape[:-2])
gc = np.zeros([n_amp] + pha_sh, dtype=float)
# compute mutual information
for p in range(n_pha):
for a in range(n_amp):
gc[a, p, ...] = nd_mi_gg(pha[p, ...], amp[a, ...])
return gc
def _fcn(xp, xa): # noqa
_erpac = np.zeros((n_amp, n_pha), dtype=float)
for a in range(n_amp):
_xa = xa.reshape(n_amp, 1, -1)
for p in range(n_pha):
_xp = xp.reshape(n_pha, 2, -1)
_erpac[a, p] = nd_mi_gg(_xp[p, ...], _xa[a, ...])
return _erpac
def ergcpac(pha, amp, smooth=None, n_jobs=-1):
"""Event Related PAC using the Gaussian Copula Mutual Information.
This function assumes that phases and amplitudes have already been
prepared i.e. phases should be represented in a unit circle
(np.c_[np.sin(pha), np.cos(pha)]) and both inputs should also have been
copnormed.
Parameters
----------
pha, amp : array_like
Respectively arrays of phases of shape (n_pha, n_times, 2, n_epochs)
and the array of amplitudes of shape (n_amp, n_times, 1, n_epochs).
Returns
-------
erpac : array_like
Array of correlation coefficients of shape (n_amp, n_pha, n_times)
References
----------
Ince et al. 2017 :cite:`ince2017statistical`
"""
# get shapes
(n_pha, n_times, _, n_epochs), n_amp = pha.shape, amp.shape[0] # noqa
# compute mutual information across trials
ergcpac = np.zeros((n_amp, n_pha, n_times))
if isinstance(smooth, int):
# define the temporal smoothing vector
vec = np.arange(smooth, n_times - smooth, 1)
times = [slice(k - smooth, k + smooth + 1) for k in vec]
# move time axis to avoid to do it inside parallel
pha, amp = np.moveaxis(pha, 1, -2), np.moveaxis(amp, 1, -2)
# function to run in parallel across times
def _fcn(t): # noqa
_erpac = np.zeros((n_amp, n_pha), dtype=float)
xp, xa = pha[..., t, :], amp[..., t, :]
for a in range(n_amp):
_xa = xa.reshape(n_amp, 1, -1)
for p in range(n_pha):
_xp = xp.reshape(n_pha, 2, -1)
_erpac[a, p] = nd_mi_gg(_xp[p, ...], _xa[a, ...])
return _erpac
# run the function across time points
_ergcpac = Parallel(n_jobs=n_jobs,
**CONFIG['JOBLIB_CFG'])(delayed(_fcn)(t)
for t in times)
# reconstruct the smoothed array
for a in range(n_amp):
for p in range(n_pha):
mean_vec = np.zeros((n_times, ), dtype=float)
for t, _gc in zip(times, _ergcpac):
ergcpac[a, p, t] += _gc[a, p]
mean_vec[t] += 1
ergcpac[a, p, :] /= mean_vec
else:
for a in range(n_amp):
for p in range(n_pha):
ergcpac[a, p, ...] = nd_mi_gg(pha[p, ...], amp[a, ...])
return ergcpac
def ergcpac(pha, amp, smooth=None, n_jobs=-1):
"""Event Related PAC computed using the Gaussian Copula Mutual Information.
Parameters
----------
pha, amp : array_like
Respectively the arrays of phases of shape (n_pha, n_times, n_epochs)
and the array of amplitudes of shape (n_amp, n_times, n_epochs).
Returns
-------
rho : array_like
Array of correlation coefficients of shape (n_amp, n_pha, n_times)
References
----------
Ince RAA, Giordano BL, Kayser C, Rousselet GA, Gross J, Schyns PG (2017) A
statistical framework for neuroimaging data analysis based on mutual
information estimated via a gaussian copula: Gaussian Copula Mutual
Information. Human Brain Mapping 38:1541–1573.
"""
# Move the trial axis to the end :
pha = np.moveaxis(pha, 1, -1)
amp = np.moveaxis(amp, 1, -1)
# get shapes
n_pha, n_times, n_epochs = pha.shape
n_amp = amp.shape[0]
# conversion for computing mi
sco = copnorm(np.stack([np.sin(pha), np.cos(pha)], axis=-2))
amp = copnorm(amp)[..., np.newaxis, :]
# compute mutual information across trials
ergcpac = np.zeros((n_amp, n_pha, n_times))
if isinstance(smooth, int):
# define the temporal smoothing vector
vec = np.arange(smooth, n_times - smooth, 1)
times = [slice(k - smooth, k + smooth + 1) for k in vec]
# move time axis to avoid to do it inside parallel
sco = np.moveaxis(sco, 1, -2)
amp = np.moveaxis(amp, 1, -2)
# function to run in parallel across times
def _fcn(xp, xa): # noqa
_erpac = np.zeros((n_amp, n_pha), dtype=float)
for a in range(n_amp):
_xa = xa.reshape(n_amp, 1, -1)
for p in range(n_pha):
_xp = xp.reshape(n_pha, 2, -1)
_erpac[a, p] = nd_mi_gg(_xp[p, ...], _xa[a, ...])
return _erpac
# run the function across time points
_ergcpac = Parallel(n_jobs=n_jobs,
**JOBLIB_CFG)(delayed(_fcn)(sco[...,
t, :], amp[...,
t, :])
for t in times)
# reconstruct the smoothed ERGCPAC array
for a in range(n_amp):
for p in range(n_pha):
mean_vec = np.zeros((n_times, ), dtype=float)
for t, _gc in zip(times, _ergcpac):
ergcpac[a, p, t] += _gc[a, p]
mean_vec[t] += 1
ergcpac[a, p, :] /= mean_vec
else:
for a in range(n_amp):
for p in range(n_pha):
ergcpac[a, p, ...] = nd_mi_gg(sco[p, ...], amp[a, ...])
return ergcpac
