Allow RA/dec unit suffix in make_sky_grid (#4988)

* Use angle_as_radians in make_skygrid

* Run black on make_sky_grid

bin/pycbc_make_sky_grid

@@ -1,11 +1,15 @@
 #!/usr/bin/env python
 
-"""For a given external trigger (GRB, FRB, neutrino, etc...), generate a sky grid covering its localization error region.
+"""For a given external trigger (GRB, FRB, neutrino, etc...), generate a sky
+grid covering its localization error region.
 
-This sky grid will be used by `pycbc_multi_inspiral` to find multi-detector gravitational wave triggers and calculate the
-coherent SNRs and related statistics. 
+This sky grid will be used by `pycbc_multi_inspiral` to find multi-detector
+gravitational wave triggers and calculate the coherent SNRs and related
+statistics. 
 
-The grid is constructed following the method described in Section V of https://arxiv.org/abs/1410.6042"""
+The grid is constructed following the method described in Section V of
+https://arxiv.org/abs/1410.6042.
+"""
 
 import numpy as np
 import argparse
@@ -15,44 +19,74 @@ from scipy.spatial.transform import Rotation as R
 import pycbc
 from pycbc.detector import Detector
 from pycbc.io.hdf import HFile
+from pycbc.types import angle_as_radians
 
 
 def spher_to_cart(sky_points):
-    """Convert spherical coordinates to cartesian coordinates.
-    """
+    """Convert spherical coordinates to cartesian coordinates."""
     cart = np.zeros((len(sky_points), 3))
-    cart[:,0] = np.cos(sky_points[:,0]) * np.cos(sky_points[:,1])
-    cart[:,1] = np.sin(sky_points[:,0]) * np.cos(sky_points[:,1])
-    cart[:,2] = np.sin(sky_points[:,1])
+    cart[:, 0] = np.cos(sky_points[:, 0]) * np.cos(sky_points[:, 1])
+    cart[:, 1] = np.sin(sky_points[:, 0]) * np.cos(sky_points[:, 1])
+    cart[:, 2] = np.sin(sky_points[:, 1])
     return cart
 
+
 def cart_to_spher(sky_points):
-    """Convert cartesian coordinates to spherical coordinates.
-    """
+    """Convert cartesian coordinates to spherical coordinates."""
     spher = np.zeros((len(sky_points), 2))
-    spher[:,0] = np.arctan2(sky_points[:,1], sky_points[:,0])
-    spher[:,1] = np.arcsin(sky_points[:,2])
+    spher[:, 0] = np.arctan2(sky_points[:, 1], sky_points[:, 0])
+    spher[:, 1] = np.arcsin(sky_points[:, 2])
     return spher
 
+
 parser = argparse.ArgumentParser(description=__doc__)
 pycbc.add_common_pycbc_options(parser)
-parser.add_argument('--ra', type=float,
-    help="Right ascension (in rad) of the center of the external trigger "
-         "error box")
-parser.add_argument('--dec', type=float,
-    help="Declination (in rad) of the center of the external trigger "
-         "error box")
-parser.add_argument('--instruments', nargs="+", type=str, required=True,
-    help="List of instruments to analyze.")
-parser.add_argument('--sky-error', type=float, required=True,
-    help="3-sigma confidence radius (in rad) of the external trigger error "
-         "box")
-parser.add_argument('--trigger-time', type=int, required=True,
-    help="Time (in s) of the external trigger")
-parser.add_argument('--timing-uncertainty', type=float, default=0.0001,
-    help="Timing uncertainty (in s) we are willing to accept")
-parser.add_argument('--output', type=str, required=True,
-        help="Name of the sky grid")
+parser.add_argument(
+    '--ra',
+    type=angle_as_radians,
+    required=True,
+    help="Right ascension of the center of the external trigger "
+    "error box. Use the rad or deg suffix to specify units, "
+    "otherwise radians are assumed.",
+)
+parser.add_argument(
+    '--dec',
+    type=angle_as_radians,
+    required=True,
+    help="Declination of the center of the external trigger "
+    "error box. Use the rad or deg suffix to specify units, "
+    "otherwise radians are assumed.",
+)
+parser.add_argument(
+    '--instruments',
+    nargs="+",
+    type=str,
+    required=True,
+    help="List of instruments to analyze.",
+)
+parser.add_argument(
+    '--sky-error',
+    type=angle_as_radians,
+    required=True,
+    help="3-sigma confidence radius of the external trigger error "
+    "box. Use the rad or deg suffix to specify units, otherwise "
+    "radians are assumed.",
+)
+parser.add_argument(
+    '--trigger-time',
+    type=int,
+    required=True,
+    help="Time (in s) of the external trigger",
+)
+parser.add_argument(
+    '--timing-uncertainty',
+    type=float,
+    default=0.0001,
+    help="Timing uncertainty (in s) we are willing to accept",
+)
+parser.add_argument(
+    '--output', type=str, required=True, help="Name of the sky grid"
+)
 
 args = parser.parse_args()
 
@@ -61,34 +95,51 @@ pycbc.init_logging(args.verbose)
 if len(args.instruments) == 1:
     parser.error('Can not make a sky grid for only one detector.')
 
-args.instruments.sort() # Put the ifos in alphabetical order
+args.instruments.sort()  # Put the ifos in alphabetical order
 detectors = args.instruments
 detectors = [Detector(d) for d in detectors]
 detector_pairs = list(itertools.combinations(detectors, 2))
 
 # Calculate the time delay for each detector pair
-tds = [detector_pairs[i][0].time_delay_from_detector(detector_pairs[i][1], args.ra, args.dec, args.trigger_time) for i in range(len(detector_pairs))]
+tds = [
+    detector_pairs[i][0].time_delay_from_detector(
+        detector_pairs[i][1], args.ra, args.dec, args.trigger_time
+    )
+    for i in range(len(detector_pairs))
+]
 
 # Calculate the light travel time between the detector pairs
-light_travel_times = [detector_pairs[i][0].light_travel_time_to_detector(detector_pairs[i][1]) for i in range(len(detector_pairs))]
+light_travel_times = [
+    detector_pairs[i][0].light_travel_time_to_detector(detector_pairs[i][1])
+    for i in range(len(detector_pairs))
+]
 
 # Calculate the required angular spacing between the sky points
-ang_spacings = [(2*args.timing_uncertainty) / np.sqrt(light_travel_times[i]**2 - tds[i]**2) for i in range(len(detector_pairs))]
+ang_spacings = [
+    (2 * args.timing_uncertainty)
+    / np.sqrt(light_travel_times[i] ** 2 - tds[i] ** 2)
+    for i in range(len(detector_pairs))
+]
 angular_spacing = min(ang_spacings)
 
 sky_points = np.zeros((1, 2))
 
 number_of_rings = int(args.sky_error / angular_spacing)
 
 # Generate the sky grid centered at the North pole
-for i in range(number_of_rings+1):
+for i in range(number_of_rings + 1):
     if i == 0:
         sky_points[0][0] = 0
-        sky_points[0][1] = np.pi/2
+        sky_points[0][1] = np.pi / 2
     else:
-        number_of_points = int(2*np.pi*i)
+        number_of_points = int(2 * np.pi * i)
         for j in range(number_of_points):
-            sky_points = np.row_stack((sky_points, np.array([j/i, np.pi/2 - i*angular_spacing])))
+            sky_points = np.row_stack(
+                (
+                    sky_points,
+                    np.array([j / i, np.pi / 2 - i * angular_spacing]),
+                )
+            )
 
 # Convert spherical coordinates to cartesian coordinates
 cart = spher_to_cart(sky_points)
@@ -103,7 +154,7 @@ ort = np.cross(grb_cart, north_pole)
 norm = np.linalg.norm(ort)
 ort /= norm
 n = -np.arccos(np.dot(grb_cart, north_pole))
-u = ort*n
+u = ort * n
 
 # Rotate the sky grid to the center of the external trigger error box
 r = R.from_rotvec(u)
@@ -112,13 +163,21 @@ rota = r.apply(cart)
 # Convert cartesian coordinates back to spherical coordinates
 spher = cart_to_spher(rota)
 
-# Calculate the time delays between the Earth center and each detector for each sky point
-time_delays = [[detectors[i].time_delay_from_earth_center(
-               spher[j][0], spher[j][1], args.trigger_time) for j in range(len(spher))] for i in range(len(detectors))]
+# Calculate the time delays between the Earth center
+# and each detector for each sky point
+time_delays = [
+    [
+        detectors[i].time_delay_from_earth_center(
+            spher[j][0], spher[j][1], args.trigger_time
+        )
+        for j in range(len(spher))
+    ]
+    for i in range(len(detectors))
+]
 
 with HFile(args.output, 'w') as hf:
-    hf['ra'] = spher[:,0]
-    hf['dec'] = spher[:,1]
+    hf['ra'] = spher[:, 0]
+    hf['dec'] = spher[:, 1]
     hf['trigger_ra'] = [args.ra]
     hf['trigger_dec'] = [args.dec]
     hf['sky_error'] = [args.sky_error]