def _get_paced_qrs_shape(signal, points, start, end):
"""
Obtains the QRSShape object corresponding to a paced QRS complex delimited
inside a signal fragment.
Parameters
----------
signal:
Signal fragment containing a paced QRS complex. The limits of the
signal should be the limits determined by the *_paced_qrs_delineation*
function.
points:
Relevant points in the signal fragment.
start:
Start point of the pace spike wrt the start of the signal.
end:
Finish point of the paced QRS wrt the start of the signal.
Returns
-------
out:
QRSShape object representing the paced beat.
"""
try:
signal = signal[start:end+1]
points = points[np.logical_and(points >= start, points <= end)] - start
verify(len(points)>0)
if points[0] != 0:
points = np.insert(points, 0, 0)
if points[-1] != len(signal) - 1:
points = np.append(points, len(signal) - 1)
verify(len(points) >= 3)
#We assume the baseline level is the start signal value of the spike
waves = extract_waves(signal, points, signal[points[0]])
verify(waves)
total_energ = sum(w.e for w in waves)
#We get the longest wave sequence with a valid QRS tag.
i = 0
while i < len(waves) and _tag_qrs(waves[:i+1]) in C.QRS_SHAPES:
i += 1
tag = _tag_qrs(waves[:i])
verify(tag in C.QRS_SHAPES)
shape = QRSShape()
shape.waves = waves[:i]
shape.energy = sum(w.e for w in shape.waves)
shape.tag = tag
shape.sig = (signal[shape.waves[0].l:shape.waves[-1].r+1] -
signal[shape.waves[0].l])
shape.maxslope = np.max(np.abs(np.diff(shape.sig)))
shape.amplitude = np.ptp(shape.sig)
shape.move(start)
verify(shape.energy/total_energ > 0.5)
return shape
except (ValueError, InconsistencyError):
return None
