Source code for yt.analysis_modules.halo_analysis.halo_quantities

"""
Halo quantity object



"""

#-----------------------------------------------------------------------------
# Copyright (c) 2013-2014, yt Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file COPYING.txt, distributed with this software.
#-----------------------------------------------------------------------------

import numpy as np

from yt.utilities.operator_registry import \
     OperatorRegistry

from .halo_callbacks import HaloCallback

quantity_registry = OperatorRegistry()

[docs]def add_quantity(name, function): quantity_registry[name] = HaloQuantity(function)
[docs]class HaloQuantity(HaloCallback): r""" A HaloQuantity is a function that takes minimally a Halo object, performs some analysis, and then returns a value that is assigned to an entry in the Halo.quantities dictionary. """ def __init__(self, function, *args, **kwargs): HaloCallback.__init__(self, function, args, kwargs) def __call__(self, halo): return self.function(halo, *self.args, **self.kwargs)
[docs]def center_of_mass(halo): if halo.particles is None: raise RuntimeError("Center of mass requires halo to have particle data.") return (halo.particles['particle_mass'] * np.array([halo.particles['particle_position_x'], halo.particles['particle_position_y'], halo.particles['particle_position_z']])).sum(axis=1) / \ halo.particles['particle_mass'].sum()
add_quantity('center_of_mass', center_of_mass)
[docs]def bulk_velocity(halo): if halo.particles is None: raise RuntimeError("Bulk velocity requires halo to have particle data.") return (halo.particles['particle_mass'] * np.array([halo.particles['particle_velocity_x'], halo.particles['particle_velocity_y'], halo.particles['particle_velocity_z']])).sum(axis=1) / \ halo.particles['particle_mass'].sum()
add_quantity('bulk_velocity', bulk_velocity)