def crossSpecgram(x,
y,
NFFT=256,
Fs=2,
detrend=mlab.detrend_none,
window=mlab.window_hanning,
noverlap=0,
pad_to=None,
sides='default',
scale_by_freq=None):
"""
Use matplotlib.mlab function, _spectral_helper, to calculate cross power between x and y in short time bins.
USAGE:
Pxy,freqs,t=crossSpecgram(x,y,NFFT=256, Fs=2, detrend=mlab.detrend_none, window=window_hanning, noverlap=0, pad_to=None, sides='default', scale_by_freq=None)
NFFT=# data points in each time bin
Fs = sample frequency in units of 1/[x]
etc. - as in other mlab functions.
Pxy=cross power
Ted Golfinopoulos, 15 Aug 2012
"""
assert (len(x) == len(y))
Pxy, freqs, t = mlab._spectral_helper(x, y, NFFT, Fs, detrend, window,
noverlap, pad_to, sides,
scale_by_freq)
return Pxy, freqs, t
def test_spectral_helper_raises(self):
# We don't use parametrize here to handle ``y = self.y``.
for kwargs in [ # Various error conditions:
{"y": self.y+1, "mode": "complex"}, # Modes requiring ``x is y``.
{"y": self.y+1, "mode": "magnitude"},
{"y": self.y+1, "mode": "angle"},
{"y": self.y+1, "mode": "phase"},
{"mode": "spam"}, # Bad mode.
{"y": self.y, "sides": "eggs"}, # Bad sides.
{"y": self.y, "NFFT": 10, "noverlap": 20}, # noverlap > NFFT.
{"NFFT": 10, "noverlap": 10}, # noverlap == NFFT.
{"y": self.y, "NFFT": 10,
"window": np.ones(9)}, # len(win) != NFFT.
]:
with pytest.raises(ValueError):
mlab._spectral_helper(x=self.y, **kwargs)
def test_spectral_helper_psd(self, mode, case):
freqs = getattr(self, f"freqs_{case}")
spec, fsp, t = mlab._spectral_helper(
x=self.y, y=self.y,
NFFT=getattr(self, f"NFFT_{case}"),
Fs=self.Fs,
noverlap=getattr(self, f"nover_{case}"),
pad_to=getattr(self, f"pad_to_{case}"),
sides=self.sides,
mode=mode)
assert_allclose(fsp, freqs, atol=1e-06)
assert_allclose(t, getattr(self, f"t_{case}"), atol=1e-06)
assert spec.shape[0] == freqs.shape[0]
assert spec.shape[1] == getattr(self, f"t_{case}").shape[0]