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pypulseq/pypulseq/make_extended_trapezoid.py
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make_extended_trapezoid.py
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from types import SimpleNamespace
import numpy as np
from pypulseq.make_arbitrary_grad import make_arbitrary_grad
from pypulseq.opts import Opts
from pypulseq.points_to_waveform import points_to_waveform
def make_extended_trapezoid(channel: str, times: np.ndarray = np.zeros(1), amplitudes: np.ndarray = np.zeros(1),
system: Opts = Opts(), max_grad: float = 0, max_slew: float = 0, skip_check: bool = False):
"""
Creates an extend trapezoidal gradient event by defined by amplitude values in `amplitudes` at time indices in
`times`.
Parameters
----------
channel : str
Orientation of extended trapezoidal gradient event. Must be one of x, y or z.
times : numpy.ndarray, optional
Time points at which `amplitudes` defines amplitude values. Default is 0.
amplitudes : numpy.ndarray, optional
Values defined at `times` time indices. Default is 0.
system : Opts, optional
System limits. Default is a system limits object initialised to default values.
max_grad : float, optional
Maximum gradient strength. Default is 0.
max_slew : float, optional
Maximum slew rate. Default is 0.
skip_check : bool, optional
Perform check. Default is false.
Returns
-------
grad : SimpleNamespace
Extended trapezoid gradient event.
"""
if channel not in ['x', 'y', 'z']:
raise ValueError()
if not np.any(times):
raise ValueError('At least one of the given times must be non-zero')
if np.any(np.diff(times) <= 0):
raise ValueError('Times must be in ascending order and all times must be distinct')
if not np.any(amplitudes):
raise ValueError('At least one of the given amplitudes must be non-zero')
if skip_check is False and times[0] > 0 and amplitudes[0] != 0:
raise ValueError('If first amplitude of a gradient is non-zero, it must connect to previous block')
if max_grad <= 0:
max_grad = system.max_grad
if max_slew <= 0:
max_slew = system.max_slew
waveform = points_to_waveform(times=times, amplitudes=amplitudes, grad_raster_time=system.grad_raster_time)
grad = make_arbitrary_grad(channel=channel, waveform=waveform, system=system, max_grad=max_grad, max_slew=max_slew,
delay=times[0])
grad.first = amplitudes[0]
grad.last = amplitudes[-1]
return grad
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