def test_dpss_windows():
"""Test computation of DPSS windows."""
import nitime as ni
N = 1000
half_nbw = 4
Kmax = int(2 * half_nbw)
dpss, eigs = dpss_windows(N, half_nbw, Kmax, low_bias=False)
with pytest.warns(None): # conversions
dpss_ni, eigs_ni = ni.algorithms.dpss_windows(N, half_nbw, Kmax)
assert_array_almost_equal(dpss, dpss_ni)
assert_array_almost_equal(eigs, eigs_ni)
dpss, eigs = dpss_windows(N,
half_nbw,
Kmax,
interp_from=200,
low_bias=False)
with pytest.warns(None): # conversions
dpss_ni, eigs_ni = ni.algorithms.dpss_windows(N,
half_nbw,
Kmax,
interp_from=200)
assert_array_almost_equal(dpss, dpss_ni)
assert_array_almost_equal(eigs, eigs_ni)
def window_edges(sig, fs, dur=0.01, axis=-1, window='hann', edges='both'):
"""Window the edges of a signal (e.g., to prevent "pops")
Parameters
----------
sig : array-like
The array to window.
fs : float
The sample rate.
dur : float
The duration to window on each edge. The default is 0.01 (10 ms).
axis : int
The axis to operate over.
window : str
The window to use. For a list of valid options, see
``scipy.signal.get_window()``, but can also be 'dpss'.
edges : str
Can be ``'leading'``, ``'trailing'``, or ``'both'`` (default).
Returns
-------
windowed_sig : array-like
The modified array (float64).
"""
fs = float(fs)
sig = np.array(sig, dtype=np.float64) # this will make a copy
sig_len = sig.shape[axis]
win_len = int(dur * fs)
if win_len > sig_len:
raise RuntimeError('cannot create window of size {0} samples (dur={1})'
'for signal with length {2}'
''.format(win_len, dur, sig_len))
if window == 'dpss':
from mne.time_frequency.multitaper import dpss_windows
win = dpss_windows(2 * win_len + 1, 1, 1)[0][0][:win_len]
win -= win[0]
win /= win.max()
else:
win = signal.windows.get_window(window, 2 * win_len)[:win_len]
valid_edges = ('leading', 'trailing', 'both')
if edges not in valid_edges:
raise ValueError('edges must be one of {0}, not "{1}"'
''.format(valid_edges, edges))
# now we can actually do the calculation
flattop = np.ones(sig_len, dtype=np.float64)
if edges in ('trailing', 'both'): # eliminate trailing
flattop[-win_len:] *= win[::-1]
if edges in ('leading', 'both'): # eliminate leading
flattop[:win_len] *= win
shape = np.ones_like(sig.shape)
shape[axis] = sig.shape[axis]
flattop.shape = shape
sig *= flattop
return sig
def window_edges(sig, fs, dur=0.01, axis=-1, window='hann', edges='both'):
"""Window the edges of a signal (e.g., to prevent "pops")
Parameters
----------
sig : array-like
The array to window.
fs : float
The sample rate.
dur : float
The duration to window on each edge. The default is 0.01 (10 ms).
axis : int
The axis to operate over.
window : str
The window to use. For a list of valid options, see
``scipy.signal.get_window()``, but can also be 'dpss'.
edges : str
Can be ``'leading'``, ``'trailing'``, or ``'both'`` (default).
Returns
-------
windowed_sig : array-like
The modified array (float64).
"""
fs = float(fs)
sig = np.array(sig, dtype=np.float64) # this will make a copy
sig_len = sig.shape[axis]
win_len = int(dur * fs)
if win_len > sig_len:
raise RuntimeError('cannot create window of size {0} samples (dur={1})'
'for signal with length {2}'
''.format(win_len, dur, sig_len))
if window == 'dpss':
from mne.time_frequency.multitaper import dpss_windows
win = dpss_windows(2 * win_len + 1, 1, 1)[0][0][:win_len]
win -= win[0]
win /= win.max()
else:
win = signal.windows.get_window(window, 2 * win_len)[:win_len]
valid_edges = ('leading', 'trailing', 'both')
if edges not in valid_edges:
raise ValueError('edges must be one of {0}, not "{1}"'
''.format(valid_edges, edges))
# now we can actually do the calculation
flattop = np.ones(sig_len, dtype=np.float64)
if edges in ('trailing', 'both'): # eliminate trailing
flattop[-win_len:] *= win[::-1]
if edges in ('leading', 'both'): # eliminate leading
flattop[:win_len] *= win
shape = np.ones_like(sig.shape)
shape[axis] = sig.shape[axis]
flattop.shape = shape
sig *= flattop
return sig
def test_dpss_windows():
"""Test computation of DPSS windows."""
import nitime as ni
N = 1000
half_nbw = 4
Kmax = int(2 * half_nbw)
dpss, eigs = dpss_windows(N, half_nbw, Kmax, low_bias=False)
dpss_ni, eigs_ni = ni.algorithms.dpss_windows(N, half_nbw, Kmax)
assert_array_almost_equal(dpss, dpss_ni)
assert_array_almost_equal(eigs, eigs_ni)
dpss, eigs = dpss_windows(N, half_nbw, Kmax, interp_from=200,
low_bias=False)
dpss_ni, eigs_ni = ni.algorithms.dpss_windows(N, half_nbw, Kmax,
interp_from=200)
assert_array_almost_equal(dpss, dpss_ni)
assert_array_almost_equal(eigs, eigs_ni)
def texture_ERB(n_freqs=20,
n_coh=None,
rho=1.,
seq=('inc', 'nb', 'inc', 'nb'),
fs=24414.0625,
dur=1.,
SAM_freq=7.,
random_state=None,
freq_lims=(200, 8000),
verbose=True):
"""Create ERB texture stimulus
Parameters
----------
n_freqs : int
Number of tones in mixture (default 20).
n_coh : int | None
Number of tones to be temporally coherent. Default (None) is
``int(np.round(n_freqs * 0.8))``.
rho : float
Correlation between the envelopes of grouped tones (default is 1.0).
seq : list
Sequence of incoherent ('inc'), coherent noise envelope ('nb'), and
SAM ('sam') mixtures. Default is ``('inc', 'nb', 'inc', 'nb')``.
fs : float
Sampling rate in Hz.
dur : float
Duration (in seconds) of each token in seq (default is 1.0).
SAM_freq : float
The SAM frequency to use.
random_state : None | int | np.random.RandomState
The random generator state used for band selection and noise
envelope generation.
freq_lims : tuple
The lower and upper frequency limits (default is (200, 8000)).
verbose : bool
If True, print the resulting ERB spacing.
Returns
-------
x : ndarray, shape (n_samples,)
The stimulus, where ``n_samples = len(seq) * (fs * dur)``
(approximately).
Notes
-----
This function requires MNE.
"""
from mne.time_frequency.multitaper import dpss_windows
from mne.utils import check_random_state
if not isinstance(seq, (list, tuple, np.ndarray)):
raise TypeError('seq must be list, tuple, or ndarray, got %s' %
type(seq))
known_seqs = ('inc', 'nb', 'sam')
for si, s in enumerate(seq):
if s not in known_seqs:
raise ValueError('all entries in seq must be one of %s, got '
'seq[%s]=%s' % (known_seqs, si, s))
fs = float(fs)
rng = check_random_state(random_state)
n_coh = int(np.round(n_freqs * 0.8)) if n_coh is None else n_coh
rise = 0.002
t = np.arange(int(round(dur * fs))) / fs
f_min, f_max = freq_lims
n_ERBs = _cams(f_max) - _cams(f_min)
del f_max
spacing_ERBs = n_ERBs / float(n_freqs - 1)
if verbose:
print('This stim will have successive tones separated by %2.2f ERBs' %
spacing_ERBs)
if spacing_ERBs < 1.0:
warnings.warn('The spacing between tones is LESS THAN 1 ERB!')
# Make a filter whose impulse response is purely positive (to avoid phase
# jumps) so that the filtered envelope is purely positive. Use a DPSS
# window to minimize sidebands. For a bandwidth of bw, to get the shortest
# filterlength, we need to restrict time-bandwidth product to a minimum.
# Thus we need a length*bw = 2 => length = 2/bw (second). Hence filter
# coefficients are calculated as follows:
b = dpss_windows(int(np.floor(2 * fs / 100.)), 1., 1)[0][0]
b -= b[0]
b /= b.sum()
# Incoherent
envrate = 14
bw = 20
incoh = 0.
for k in range(n_freqs):
f = _inv_cams(_cams(f_min) + spacing_ERBs * k)
env = _make_narrow_noise(bw, envrate, dur, fs, rise, rng)
env[env < 0] = 0
env = np.convolve(b, env)[:len(t)]
incoh += _scale_sound(
window_edges(env * np.sin(2 * np.pi * f * t),
fs,
rise,
window='dpss'))
incoh /= rms(incoh)
# Coherent (noise band)
stims = dict(inc=0., nb=0., sam=0.)
group = np.sort(rng.permutation(np.arange(n_freqs))[:n_coh])
for kind in known_seqs:
if kind == 'nb': # noise band
env_coh = _make_narrow_noise(bw, envrate, dur, fs, rise, rng)
else: # 'nb' or 'inc'
env_coh = 0.5 + np.sin(2 * np.pi * SAM_freq * t) / 2.
env_coh = window_edges(env_coh, fs, rise, window='dpss')
env_coh[env_coh < 0] = 0
env_coh = np.convolve(b, env_coh)[:len(t)]
if kind == 'inc':
use_group = [] # no coherent ones
else: # 'nb' or 'sam'
use_group = group
for k in range(n_freqs):
f = _inv_cams(_cams(f_min) + spacing_ERBs * k)
env_inc = _make_narrow_noise(bw, envrate, dur, fs, rise, rng)
env_inc[env_inc < 0] = 0.
env_inc = np.convolve(b, env_inc)[:len(t)]
if k in use_group:
env = np.sqrt(rho) * env_coh + np.sqrt(1 - rho**2) * env_inc
else:
env = env_inc
stims[kind] += _scale_sound(
window_edges(env * np.sin(2 * np.pi * f * t),
fs,
rise,
window='dpss'))
stims[kind] /= rms(stims[kind])
stim = np.concatenate([stims[s] for s in seq])
stim = 0.01 * stim / rms(stim)
return stim
def texture_ERB(n_freqs=20, n_coh=None, rho=1., seq=('inc', 'nb', 'inc', 'nb'),
fs=24414.0625, dur=1., SAM_freq=7., random_state=None,
freq_lims=(200, 8000), verbose=True):
"""Create ERB texture stimulus
Parameters
----------
n_freqs : int
Number of tones in mixture (default 20).
n_coh : int | None
Number of tones to be temporally coherent. Default (None) is
``int(np.round(n_freqs * 0.8))``.
rho : float
Correlation between the envelopes of grouped tones (default is 1.0).
seq : list
Sequence of incoherent ('inc'), coherent noise envelope ('nb'), and
SAM ('sam') mixtures. Default is ``('inc', 'nb', 'inc', 'nb')``.
fs : float
Sampling rate in Hz.
dur : float
Duration (in seconds) of each token in seq (default is 1.0).
SAM_freq : float
The SAM frequency to use.
random_state : None | int | np.random.RandomState
The random generator state used for band selection and noise
envelope generation.
freq_lims : tuple
The lower and upper frequency limits (default is (200, 8000)).
verbose : bool
If True, print the resulting ERB spacing.
Returns
-------
x : ndarray, shape (n_samples,)
The stimulus, where ``n_samples = len(seq) * (fs * dur)``
(approximately).
Notes
-----
This function requires MNE.
"""
from mne.time_frequency.multitaper import dpss_windows
from mne.utils import check_random_state
if not isinstance(seq, (list, tuple, np.ndarray)):
raise TypeError('seq must be list, tuple, or ndarray, got %s'
% type(seq))
known_seqs = ('inc', 'nb', 'sam')
for si, s in enumerate(seq):
if s not in known_seqs:
raise ValueError('all entries in seq must be one of %s, got '
'seq[%s]=%s' % (known_seqs, si, s))
fs = float(fs)
rng = check_random_state(random_state)
n_coh = int(np.round(n_freqs * 0.8)) if n_coh is None else n_coh
rise = 0.002
t = np.arange(int(round(dur * fs))) / fs
f_min, f_max = freq_lims
n_ERBs = _cams(f_max) - _cams(f_min)
del f_max
spacing_ERBs = n_ERBs / float(n_freqs - 1)
if verbose:
print('This stim will have successive tones separated by %2.2f ERBs'
% spacing_ERBs)
if spacing_ERBs < 1.0:
warnings.warn('The spacing between tones is LESS THAN 1 ERB!')
# Make a filter whose impulse response is purely positive (to avoid phase
# jumps) so that the filtered envelope is purely positive. Use a DPSS
# window to minimize sidebands. For a bandwidth of bw, to get the shortest
# filterlength, we need to restrict time-bandwidth product to a minimum.
# Thus we need a length*bw = 2 => length = 2/bw (second). Hence filter
# coefficients are calculated as follows:
b = dpss_windows(int(np.floor(2 * fs / 100.)), 1., 1)[0][0]
b -= b[0]
b /= b.sum()
# Incoherent
envrate = 14
bw = 20
incoh = 0.
for k in range(n_freqs):
f = _inv_cams(_cams(f_min) + spacing_ERBs * k)
env = _make_narrow_noise(bw, envrate, dur, fs, rise, rng)
env[env < 0] = 0
env = np.convolve(b, env)[:len(t)]
incoh += _scale_sound(window_edges(
env * np.sin(2 * np.pi * f * t), fs, rise, window='dpss'))
incoh /= rms(incoh)
# Coherent (noise band)
stims = dict(inc=0., nb=0., sam=0.)
group = np.sort(rng.permutation(np.arange(n_freqs))[:n_coh])
for kind in known_seqs:
if kind == 'nb': # noise band
env_coh = _make_narrow_noise(bw, envrate, dur, fs, rise, rng)
else: # 'nb' or 'inc'
env_coh = 0.5 + np.sin(2 * np.pi * SAM_freq * t) / 2.
env_coh = window_edges(env_coh, fs, rise, window='dpss')
env_coh[env_coh < 0] = 0
env_coh = np.convolve(b, env_coh)[:len(t)]
if kind == 'inc':
use_group = [] # no coherent ones
else: # 'nb' or 'sam'
use_group = group
for k in range(n_freqs):
f = _inv_cams(_cams(f_min) + spacing_ERBs * k)
env_inc = _make_narrow_noise(bw, envrate, dur, fs, rise, rng)
env_inc[env_inc < 0] = 0.
env_inc = np.convolve(b, env_inc)[:len(t)]
if k in use_group:
env = np.sqrt(rho) * env_coh + np.sqrt(1 - rho ** 2) * env_inc
else:
env = env_inc
stims[kind] += _scale_sound(window_edges(
env * np.sin(2 * np.pi * f * t), fs, rise, window='dpss'))
stims[kind] /= rms(stims[kind])
stim = np.concatenate([stims[s] for s in seq])
stim = 0.01 * stim / rms(stim)
return stim