Move the pycbc array type and some constants away from lalsuite

bin/live/pycbc_live_plot_combined_single_significance_fits

@@ -22,9 +22,8 @@ import matplotlib
 matplotlib.use('agg')
 from matplotlib import pyplot as plt
 
-from lal import gpstime
-
 import pycbc
+from pycbc.live import strip_time
 from pycbc.io.hdf import HFile
 
 
@@ -115,9 +114,10 @@ t = min_start
 # Last tick will be the midnight after the last datapoint
 while t < max_end + 86400:
     # Strip off the time information, ticks are at midnight
-    time_dt = gpstime.gps_to_utc(t).date()
-    xtix_labels.append(time_dt.strftime("%Y-%m-%d"))
-    xtix.append(gpstime.utc_to_gps(time_dt).gpsSeconds)
+
+    time_midnight, str_date = strip_time(t)
+    xtix_labels.append(str_date)
+    xtix.append(time_midnight)
     t += 86400
 
 logging.info("Plotting fits information")

bin/live/pycbc_live_plot_single_significance_fits

@@ -23,7 +23,7 @@ import matplotlib
 matplotlib.use('agg')
 from matplotlib import pyplot as plt
 
-from lal import gpstime
+from astropy.time import Time
 
 import pycbc
 from pycbc.bin_utils import IrregularBins
@@ -81,8 +81,14 @@ with HFile(args.trigger_fits_file, 'r') as trfit_f:
     fit_function = {ifo: trfit_f[ifo].attrs['fit_function'] for ifo in ifos}
     start_time = trfit_f.attrs['fit_start_gps_time']
     end_time = trfit_f.attrs['fit_end_gps_time']
-    start_str = gpstime.gps_to_utc(start_time).strftime("%Y-%m-%d %H:%M:%S")
-    end_str = gpstime.gps_to_utc(end_time).strftime("%Y-%m-%d %H:%M:%S")
+    start_str = Time(
+        start_time,
+        format='gps'
+    ).to_datetime().strftime("%Y-%m-%d %H:%M:%S")
+    end_str = Time(
+        end_time,
+        format='gps'
+    ).to_datetime().strftime("%Y-%m-%d %H:%M:%S")
 
     # Get the triggers for each detector
     # (This is ones which passed the cuts in the fitting code)

bin/live/pycbc_live_supervise_collated_trigger_fits

@@ -14,8 +14,7 @@ import numpy as np
 
 from datetime import datetime, timedelta
 
-import lal
-from lal import gpstime
+from astropy.time import Time
 
 import pycbc
 from pycbc.live import supervision as sv
@@ -44,16 +43,10 @@ def get_true_date(replay_day_dt, controls):
     replay_start_time = int(controls['replay-start-time'])
     true_start_time = int(controls['true-start-time'])
     replay_duration = int(controls['replay-duration'])
-    rep_start_utc = lal.GPSToUTC(replay_start_time)[0:6]
-
-    dt_replay_start = datetime(
-        year=rep_start_utc[0],
-        month=rep_start_utc[1],
-        day=rep_start_utc[2],
-        hour=rep_start_utc[3],
-        minute=rep_start_utc[4],
-        second=rep_start_utc[5]
-    )
+    dt_replay_start = Time(
+        replay_start_time,
+        format='gps'
+    ).to_datetime()
 
     td = (replay_day_dt - dt_replay_start).total_seconds()
 
@@ -62,15 +55,11 @@ def get_true_date(replay_day_dt, controls):
 
     # Add this on to the original start time to get the current time of
     # the replay data
-    true_utc = lal.GPSToUTC(true_start_time)[0:6]
-    dt_true_start = datetime(
-        year=true_utc[0],
-        month=true_utc[1],
-        day=true_utc[2],
-        hour=true_utc[3],
-        minute=true_utc[4],
-        second=true_utc[5]
-    )
+    dt_true_start = Time(
+        true_start_time,
+        format='gps'
+    ).to_datetime()
+
     # Original time of the data being replayed right now
     return dt_true_start + timedelta(seconds=time_since_replay)
 
@@ -91,8 +80,16 @@ def trigger_collation(
         'pycbc_live_collate_triggers',
     ]
     collate_args += sv.dict_to_args(collation_options)
-    gps_start = gpstime.utc_to_gps(day_dt).gpsSeconds
-    gps_end = gpstime.utc_to_gps(day_dt + timedelta(days=1)).gpsSeconds
+    gps_start = int(Time(
+        day_dt,
+        format='datetime',
+        scale='utc'
+    ).gps)
+    gps_end = int(Time(
+        day_dt + timedelta(days=1),
+        format='datetime',
+        scale='utc'
+    ).gps)
 
     trig_merge_file = os.path.join(
         output_dir,
@@ -326,8 +323,16 @@ def single_significance_fits(
     )
     daily_args = ['pycbc_live_single_significance_fits']
 
-    gps_start_time = gpstime.utc_to_gps(day_dt).gpsSeconds
-    gps_end_time = gpstime.utc_to_gps(day_dt + timedelta(days=1)).gpsSeconds
+    gps_start_time = int(Time(
+        day_dt,
+        format='datetime',
+        scale='utc'
+    ).gps)
+    gps_end_time = int(Time(
+        day_dt + timedelta(days=1),
+        format='datetime',
+        scale='utc'
+    ).gps)
     daily_fit_options['gps-start-time'] = f'{gps_start_time:d}'
     daily_fit_options['gps-end-time'] = f'{gps_end_time:d}'
     daily_args += sv.dict_to_args(daily_fit_options)
@@ -497,10 +502,21 @@ def daily_dq_trigger_rates(
 
     start_time = get_true_date(day_dt, daily_dq_controls)
 
-    gps_start_time = gpstime.utc_to_gps(start_time).gpsSeconds
-    gps_end_time = gpstime.utc_to_gps(start_time + timedelta(days=1)).gpsSeconds
-
-    offset = gpstime.utc_to_gps(day_dt).gpsSeconds - gps_start_time
+    gps_start_time = int(Time(
+        start_time,
+        format='datetime',
+        scale='utc'
+    ).gps)
+    gps_end_time = int(Time(
+        start_time + timedelta(days=1),
+        format='datetime',
+        scale='utc'
+    ).gps)
+    offset = int(Time(
+        day_dt,
+        format='datetime',
+        scale='utc'
+    ).gps) - gps_start_time
 
     ddtr_out_full = os.path.join(output_dir, ddtr_out_fname)
     daily_dq_args = ['pycbc_live_collated_dq_trigger_rates']

pycbc/constants.py

@@ -0,0 +1,100 @@
+"""
+Constants module for PyCBC.
+
+This module provides constants from various packages (LAL, astropy, numpy)
+based on a preferred order of availability. This helps minimize dependency bloat
+by relying on smaller, more general packages (astropy/numpy) when the large
+LALSuite dependency is not available.
+
+The priority order for constant lookup is: LAL > Astropy / SciPy / NumPy
+"""
+
+import logging
+import os
+
+import numpy as np
+from astropy import (
+    constants as aconstants,
+    units as aunits
+)
+
+from pycbc.libutils import import_optional
+
+lal = import_optional('lal')
+
+# We define a global logger for this module
+logger = logging.getLogger('pycbc.constants')
+
+# Get the environment variable which defines which constants to use
+# Allowed values are 'default' or 'lal'
+_CONSTANTS = os.environ.get('PYCBC_CONSTANT_SOURCE', 'default').lower()
+
+
+# first, do mappings for constants where the value is directly in astropy/numpy
+# All are in SI units
+_DEFAULT_MAPPING = {
+    'C_SI': aconstants.c.value,             # Speed of light
+    'G_SI': aconstants.G.value,             # Gravitational constant
+    'MSUN_SI': aconstants.M_sun.value,      # Mass of the Sun
+    'PC_SI': aconstants.pc.value,           # Parsec
+    'REARTH_SI': aconstants.R_earth.value,  # Earth equatorial radius
+    'YRJUL_SI': aunits.year.to(aunits.s),   # years in seconds
+    'PI': np.pi,
+    'TWOPI': 2 * np.pi,
+    'GAMMA': np.euler_gamma,
+    'PI_4': np.pi / 4.,
+    'LN2': np.log(2.)
+}
+
+# We need to define some constants from astropy values
+MSUN_SI = _DEFAULT_MAPPING['MSUN_SI']
+C_SI = _DEFAULT_MAPPING['C_SI']
+G_SI = _DEFAULT_MAPPING['G_SI']
+
+MTSUN_SI = MSUN_SI * G_SI / (C_SI ** 3)
+MRSUN_SI = MSUN_SI * G_SI / (C_SI * C_SI)
+
+# Add in these hybrid constants
+_DEFAULT_MAPPING.update({
+    'MTSUN_SI': MTSUN_SI,
+    'MRSUN_SI': MRSUN_SI
+})
+
+# Define the Constant Lookup Function
+def get_constant(name):
+    """
+    Retrieves a constant value by name from the preferred order of packages.
+
+    The order of preference is: Astropy + NumPy > LAL
+
+    Parameters
+    ----------
+    name : str
+        The name of the constant to retrieve (e.g., 'C_SI' for the speed of light).
+
+    Returns
+    -------
+    float or object
+        The value of the constant.
+
+    Raises
+    ------
+    NotImplementedError
+        If the constant is not found in any of the available packages.
+    """
+
+
+    if _CONSTANTS == 'lal': # Allow lal, or LAL, or whatever
+        return getattr(lal, name)
+
+    elif name in _DEFAULT_MAPPING:
+        return _DEFAULT_MAPPING[name]
+
+    raise NotImplementedError(
+        'Contact the PyCBC team, this should never happen. You are '
+        'trying to use a constant which is not defined.'
+    )
+
+# Expose the constants as attributes of this module:
+for const_name in _DEFAULT_MAPPING:
+    globals()[const_name] = get_constant(const_name)