calc_rf_center.py
f9bf5a742188feature-gammamri

calc_rf_center.py
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			from types import SimpleNamespace
			from typing import Tuple

			import numpy as np


			def calc_rf_center(rf: SimpleNamespace) -> Tuple[float, float]:
			"""
			Calculate the time point of the effective rotation calculated as the peak of the radio-frequency amplitude for the
			shaped pulses and the center of the pulse for the block pulses. Zero padding in the radio-frequency pulse is
			considered as a part of the shape. Delay field of the radio-frequency object is not taken into account.

			Parameters
			----------
			rf : SimpleNamespace
			Radio-frequency pulse event.

			Returns
			-------
			time_center : float
			Time point of the center of the radio-frequency pulse.
			id_center : float
			Corresponding position of `time_center` in the radio-frequency pulse's envelope.
			"""
			# We detect the excitation peak; if i is a plateau we take its center
			rf_max = max(abs(rf.signal))
			i_peak = np.where(abs(rf.signal) >= rf_max * 0.99999)[0]
			time_center = (rf.t[i_peak[0]] + rf.t[i_peak[-1]]) / 2
			id_center = i_peak[round((len(i_peak) - 1) / 2)]

			return time_center, id_center