Move the pycbc array type and some constants away from lalsuite #5217
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| """ | ||
| Constants module for PyCBC. | ||
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| 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. | ||
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| The priority order for constant lookup is: LAL > Astropy > NumPy | ||
| """ | ||
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| import logging | ||
| import warnings | ||
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| # We define a global logger for this module | ||
| logger = logging.getLogger('pycbc.constants') | ||
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| # Attempt to import LALSuite | ||
| try: | ||
| import lal | ||
| _LAL_AVAILABLE = True | ||
| logger.debug("LAL constants module found.") | ||
| except ImportError: | ||
| lal = None | ||
| _LAL_AVAILABLE = False | ||
| logger.debug("LAL constants module not found.") | ||
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| import numpy as np | ||
| from astropy import ( | ||
| constants as aconstants, | ||
| units as aunits | ||
| ) | ||
| # first, do mappings for constants which the fallback is directly in astropy/numpy | ||
| # All are in SI units | ||
| _FALLBACK_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 | ||
| } | ||
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| # We need to define some constants from astropy values | ||
| MSUN_SI = _FALLBACK_MAPPING['MSUN_SI'] | ||
| C_SI = _FALLBACK_MAPPING['C_SI'] | ||
| G_SI = _FALLBACK_MAPPING['G_SI'] | ||
| MTSUN_SI = MSUN_SI * G_SI / (C_SI ** 3) | ||
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| # Add in these hybrid constants | ||
| _FALLBACK_MAPPING.update({ | ||
| 'MTSUN_SI': MTSUN_SI | ||
| }) | ||
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| # Define the Constant Lookup Function | ||
| def get_constant(name): | ||
| """ | ||
| Retrieves a constant value by name from the preferred order of packages. | ||
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| The order of preference is: LAL > Astropy > NumPy | ||
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| Parameters | ||
| ---------- | ||
| name : str | ||
| The name of the constant to retrieve (e.g., 'C_SI' for the speed of light). | ||
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| Returns | ||
| ------- | ||
| float or object | ||
| The value of the constant. | ||
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| Raises | ||
| ------ | ||
| NotImplementedError | ||
| If the constant is not found in any of the available packages. | ||
| """ | ||
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| if _LAL_AVAILABLE: | ||
| return getattr(lal, name) | ||
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| elif name in _FALLBACK_MAPPING: | ||
| return _FALLBACK_MAPPING[name] | ||
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| raise NotImplementedError( | ||
| 'Contact the PyCBC team, this should never happen. You are ' | ||
| 'trying to use a LAL constant which doesnt have an astropy/numpy ' | ||
| 'fallback defined.' | ||
| ) | ||
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| # Expose the constants as attributes of the module | ||
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| C_SI = get_constant('C_SI') | ||
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| G_SI = get_constant('G_SI') | ||
| MTSUN_SI = get_constant('MTSUN_SI') | ||
| MSUN_SI = get_constant('MSUN_SI') | ||
| PC_SI = get_constant('PC_SI') | ||
| REARTH_SI = get_constant('REARTH_SI') | ||
| YRJUL_SI = get_constant('YRJUL_SI') | ||
| PI = get_constant('PI') | ||
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@GarethCabournDavies @spxiwh
In fact, almost everything in this mapping is something we should consider just not using lal for. A few of these may require checking (earth_si, I could imagine some specific value was chosen that is not known to different precision). Most of these though don't need to come from lal in any situation I can imagine.
I'd even prefer we don't have fallbacks (at least not without understanding the potential use case a bit more), because that means there could be unexpected behavior if say lal is or is not the source.