Make detectors and ref time properties of the instance (to be continu…

…ed…)

pycbc/tmpltbank/sky_grid.py

@@ -11,7 +11,7 @@
 
 
 class SkyGrid:
-    def __init__(self, ra, dec):
+    def __init__(self, ra, dec, detectors, ref_gps_time):
         """Initialize a sky grid from a list of RA/dec coordinates.
 
         Parameters
@@ -20,15 +20,22 @@ def __init__(self, ra, dec):
             Right ascensions for each point UNITS AND ANGULAR CONVENTION.
         dec: iterable of floats
             Declination for each point UNITS AND ANGULAR CONVENTION.
+        detectors: iterable of str
+            List of detector names associated with the sky grid, typically the
+            detectors for which the grid has been placed or is to be placed.
+            The detectors will be used when calculating the antenna pattern
+            functions and time delays from Earth center.
+        ref_gps_time: float
+            Reference GPS time associated with the sky grid. This will be used
+            when calculating the antenna pattern functions and time delays from
+            Earth center.
         """
-        # Question: should the list of detectors and reference times be part of
-        # the SkyGrid object? Or should they be given each time they are needed,
-        # independently? This decision will affect the `calculate_*()` methods
-        # down below.
         # We store the points in a 2D array internally, first dimension runs
         # over the list of points, second dimension is RA/dec.
         # Question: should we use Astropy sky positions instead?
         self.positions = np.vstack([ra, dec]).T
+        self.detectors = sorted(detectors)
+        self.ref_gps_time = ref_gps_time
 
     def __len__(self):
         """Returns the number of points in the sky grid."""
@@ -61,6 +68,7 @@ def from_cli(cls, cli_parser, cli_args):
                 )
             return cls.read_from_file(cli_args.sky_grid)
         if cli_args.ra is not None and cli_args.dec is not None:
+            # FIXME where do we get the detectors and ref time from?
             return cls([cli_args.ra], [cli_args.dec])
         cli_parser.error(
             'Please specify a sky grid via --sky-grid or a single sky '
@@ -73,44 +81,48 @@ def read_from_file(cls, path):
         with h5py.File(path, 'r') as hf:
             ra = hf['ra'][:]
             dec = hf['dec'][:]
-        return cls(ra, dec)
+            detectors = hf.attrs['detectors']
+            ref_gps_time = hf.attrs['ref_gps_time']
+        return cls(ra, dec, detectors, ref_gps_time)
 
     def write_to_file(self, path):
         """Writes a sky grid to an HDF5 file."""
         with h5py.File(path, 'w') as hf:
             hf['ra'] = self.ras
             hf['dec'] = self.decs
+            hf.attrs['detectors'] = self.detectors
+            hf.attrs['ref_gps_time'] = self.ref_gps_time
 
-    def calculate_antenna_patterns(self, detector_names, gps_time):
+    def calculate_antenna_patterns(self):
         """Calculate the antenna pattern functions at each point in the grid
-        for a list of GW detectors. Return a dict, keyed by detector name,
-        whose items are 2-dimensional Numpy arrays. The first dimension of
-        these arrays runs over the sky grid, and the second dimension runs over
-        the plus and cross polarizations.
+        for the list of GW detectors specified at instantiation. Return a dict,
+        keyed by detector name, whose items are 2-dimensional Numpy arrays.
+        The first dimension of these arrays runs over the sky grid, and the
+        second dimension runs over the plus and cross polarizations.
         """
         result = {}
-        for det_name in detector_names:
+        for det_name in self.detectors:
             det = Detector(det_name)
             result[det_name] = np.empty((len(self), 2))
             for i, (ra, dec) in enumerate(self):
                 result[det_name][i] = det.antenna_pattern(
-                    ra, dec, 0, t_gps=gps_time
+                    ra, dec, 0, t_gps=self.ref_gps_time
                 )
         return result
 
-    def calculate_time_delays(self, detector_names, gps_time):
-        """Calculate the time delays from the Earth center to a list of GW
-        detectors at each point in the grid. Return a dict, keyed by detector
-        name, whose items are 1-dimensional Numpy arrays containing the time
-        delays for each sky point.
+    def calculate_time_delays(self):
+        """Calculate the time delays from the Earth center to each GW detector
+        specified at instantiation, for each point in the grid. Return a dict,
+        keyed by detector name, whose items are 1-dimensional Numpy arrays
+        containing the time delays for each sky point.
         """
         result = {}
-        for det_name in detector_names:
+        for det_name in self.detectors:
             det = Detector(det_name)
             result[det_name] = np.empty(len(self))
             for i, (ra, dec) in enumerate(self):
                 result[det_name][i] = det.time_delay_from_earth_center(
-                    ra, dec, t_gps=gps_time
+                    ra, dec, t_gps=self.ref_gps_time
                 )
         return result