Merge pull request #51 from scipp/fix-open-times-anticlockwise

Fix chopper open and close times when direction is anticlockwise

src/tof/chopper.py

@@ -106,15 +106,10 @@ def open_close_times(
  # large
  phases = sc.arange(uuid.uuid4().hex, -1, nrot) * two_pi + self.phase.to(
  unit='rad'
- ) * ({Clockwise: 1, AntiClockwise: -1}[self.direction])
- # Note that the order is important here: we need (phases + open/close) to get
- # the correct dimension order when we flatten below.
- open_times = (phases + self.open.to(unit='rad', copy=False)).flatten(
- to=self.open.dim
- )
- close_times = (phases + self.close.to(unit='rad', copy=False)).flatten(
- to=self.close.dim
  )
+
+ open_times = self.open.to(unit='rad', copy=False)
+ close_times = self.close.to(unit='rad', copy=False)
  # If the chopper is rotating anti-clockwise, we mirror the openings because the
  # first cutout will be the last to open.
  if self.direction == AntiClockwise:
@@ -130,6 +125,10 @@ def open_close_times(
  unit=open_times.unit,
  ),
  )
+ # Note that the order is important here: we need (phases + open/close) to get
+ # the correct dimension order when we flatten.
+ open_times = (phases + open_times).flatten(to=self.open.dim)
+ close_times = (phases + close_times).flatten(to=self.close.dim)
  open_times /= self.omega
  close_times /= self.omega
  return (
@@ -141,7 +140,7 @@ def __repr__(self) -> str:
  return (
  f"Chopper(name={self.name}, distance={self.distance:c}, "
  f"frequency={self.frequency:c}, phase={self.phase:c}, "
- f"cutouts={len(self.open)})"
+ f"direction={self.direction.name}, cutouts={len(self.open)})"
  )
 
  def as_dict(self):
@@ -152,6 +151,7 @@ def as_dict(self):
  'distance': self.distance,
  'phase': self.phase,
  'name': self.name,
+ 'direction': self.direction,
  }
 
 

tests/chopper_test.py

@@ -173,12 +173,10 @@ def test_open_close_times_counter_rotation():
  direction=tof.AntiClockwise,
  )
 
- topen1, tclose1 = chopper1.open_close_times(0.2 * sec)
+ topen1, tclose1 = chopper1.open_close_times(0.0 * sec)
  topen2, tclose2 = chopper2.open_close_times(0.0 * sec)
- # Note that the first chopper will have one more rotation before t=0, so we slice
- # out the first two open/close times
- assert sc.allclose(topen1[2:], topen2)
- assert sc.allclose(tclose1[2:], tclose2)
+ assert sc.allclose(topen1, topen2)
+ assert sc.allclose(tclose1, tclose2)
 
 
 def test_open_close_times_counter_rotation_with_phase():
@@ -209,6 +207,35 @@ def test_open_close_times_counter_rotation_with_phase():
  )
 
 
+def test_open_close_anticlockwise_multiple_rotations():
+ chopper = tof.Chopper(
+ frequency=10.0 * Hz,
+ open=sc.array(dims=["cutout"], values=[10.0, 90.0], unit="deg"),
+ close=sc.array(dims=["cutout"], values=[20.0, 130.0], unit="deg"),
+ distance=10.0 * meter,
+ phase=0 * deg,
+ direction=tof.AntiClockwise,
+ )
+
+ two_rotations_open, two_rotations_close = chopper.open_close_times(0.0 * sec)
+ three_rotations_open, three_rotations_close = chopper.open_close_times(0.2 * sec)
+ four_rotations_open, four_rotations_close = chopper.open_close_times(0.3 * sec)
+
+ assert len(two_rotations_open) == 4
+ assert len(three_rotations_open) == 6
+ assert len(four_rotations_open) == 8
+ assert len(two_rotations_close) == 4
+ assert len(three_rotations_close) == 6
+ assert len(four_rotations_close) == 8
+
+ assert sc.allclose(two_rotations_open, three_rotations_open[:-2])
+ assert sc.allclose(two_rotations_close, three_rotations_close[:-2])
+ assert sc.allclose(three_rotations_open, four_rotations_open[:-2])
+ assert sc.allclose(three_rotations_close, four_rotations_close[:-2])
+ assert sc.allclose(two_rotations_open, four_rotations_open[:-4])
+ assert sc.allclose(two_rotations_close, four_rotations_close[:-4])
+
+
 def test_bad_direction_raises():
  f = 10.0 * Hz
  op = sc.array(dims=['cutout'], values=[10.0], unit='deg')