Merge pull request #27 from sot/pitch-roll-constraint

Change allowed_rolldev to use chandra_models

setup.py

@@ -9,11 +9,9 @@
 
 packages = ["ska_sun", "ska_sun.tests"]
 package_dir = {name: name}
-package_data = {name: ["data/*fits.gz"]}
 
 duplicate_package_info(packages, name, namespace)
 duplicate_package_info(package_dir, name, namespace)
-duplicate_package_info(package_data, name, namespace)
 
 setup(
     name=name,
@@ -25,7 +23,6 @@
     zip_safe=False,
     package_dir=package_dir,
     packages=packages,
-    package_data=package_data,
     tests_require=["pytest"],
     cmdclass=cmdclass,
 )

ska_sun/sun.py

@@ -3,7 +3,6 @@
 Utility for calculating sun position, pitch angle and values related to roll.
 """
 from math import acos, asin, atan2, cos, degrees, pi, radians, sin
-from pathlib import Path
 
 import numpy as np
 import Ska.quatutil
@@ -12,14 +11,18 @@
 from chandra_aca.transform import radec_to_eci
 from Quaternion import Quat
 from ska_helpers.utils import LazyVal
+from ska_helpers import chandra_models
+
+
+CHANDRA_MODELS_PITCH_ROLL_FILE = "chandra_models/pitch_roll/pitch_roll_constraint.csv"
 
 
 def load_roll_table():
-    dat = Table.read(Path(__file__).parent / "data" / "pitch_roll.fits.gz")
+    """Load the pitch/roll table from the chandra_models repo."""
+    dat = chandra_models.get_data(CHANDRA_MODELS_PITCH_ROLL_FILE, read_func=Table.read)
+    # Sanity check that the pitch values are monotonically increasing.
+    assert np.all(np.diff(dat["pitch"]) > 0)
 
-    # Add a terminating row to the data such that for pitch at or greater
-    # than 180 the allowed roll deviation is defined as 0.
-    dat.add_row({"pitch": 180, "rolldev": 0})
     return dat
 
 
@@ -28,17 +31,25 @@ def load_roll_table():
 
 def allowed_rolldev(pitch):
     """Get allowed roll deviation (off-nominal roll) for the given ``pitch``.
-    :param pitch: Sun pitch angle (deg)
-    :returns: Roll deviation (deg)
+
+    This performs a linear interpolation of the values in the pitch/roll table in
+    the chandra_models repo in ``chandra_models/pitch_roll/pitch_roll_constraint.csv``.
+
+    For pitch values outside the range of the table the returned rolldev is -1.0,
+    corresonding to a pitch angle outside of the planning limits.
+
+    :param pitch: float, ndarray
+        Sun pitch angle (deg)
+    :returns: float, ndarray
+        Roll deviation (deg)
     """
-    idx1 = np.searchsorted(ROLL_TABLE.val["pitch"], pitch, side="right")
-    idx0 = idx1 - 1
-    idx_max = len(ROLL_TABLE.val) - 1
-    idx0 = np.clip(idx0, 0, idx_max)
-    idx1 = np.clip(idx1, 0, idx_max)
-    val0 = ROLL_TABLE.val["rolldev"][idx0]
-    val1 = ROLL_TABLE.val["rolldev"][idx1]
-    out = np.minimum(val0, val1)  # works even for a vector input for `pitch`
+    out = np.interp(
+        x=pitch,
+        xp=ROLL_TABLE.val["pitch"],
+        fp=ROLL_TABLE.val["off_nom_roll"],
+        left=-1.0,
+        right=-1.0,
+    )
     return out
 
 

ska_sun/tests/test_sun.py

@@ -1,6 +1,7 @@
 # Licensed under a 3-clause BSD style license - see LICENSE.rst
 
 import numpy as np
+import pytest
 from Quaternion import Quat
 
 from ..sun import (
@@ -13,29 +14,36 @@
 from ..sun import pitch as sun_pitch
 from ..sun import position
 
-
-def test_allowed_rolldev():
-    # Test array of pitchs and allowed roll dev
-    testarr = [
+# Expected pitch, rolldev pairs
+exp_pitch_rolldev = np.array(
+    [
+        [0, -1.0],
+        [40, -1.0],
+        [56.0, -1.0],
+        [85.49229, 4.95597],
+        [85.52, 4.9560848],
+        [124.99, 12.23652],
+        [125, 12.2380],
         [135, 13.979],
         [138, 14.516],
-        [0, 0],
-        [40, 0],
-        [179.9, 18.748772],
-        [179.997, 0],
-        [180, 0],
-        [181, 0],
-        [85.49229, 13.677669],
-        [85.52, 18.756727],
-        [124.99, 18.748772],
-        [125, 17.0],
+        [177.9, 18.749],
+        [177.997, 18.749],
+        [178.0, -1.0],
+        [180, -1.0],
+        [181, -1.0],
     ]
-    for pitch, rolldev in testarr:
-        assert np.isclose(allowed_rolldev(pitch), rolldev)
+)
+
+
+@pytest.mark.parametrize("pitch, rolldev", exp_pitch_rolldev)
+def test_allowed_rolldev(pitch, rolldev):
+    # Test array of pitchs and allowed roll dev
+    assert np.isclose(allowed_rolldev(pitch), rolldev)
+
 
-    # Also test with pitch as vector
+def test_allowed_rolldev_vector():
     assert np.allclose(
-        allowed_rolldev(np.array(testarr)[:, 0]), np.array(testarr)[:, 1]
+        allowed_rolldev(exp_pitch_rolldev[:, 0]), exp_pitch_rolldev[:, 1]
     )