galaxychop.data module

Module galaxy-chop.

class galaxychop.data.ParticleSetType(value)[source]

Bases: enum.IntEnum

Name of the particle type.

Name and number that are used to describe the particle type in the ParticleSet class.

classmethod mktype(v)[source]

Create a ParticleSetType from name, or value.

humanize()[source]

Particle type name in lower case.

class galaxychop.data.ParticleSet(ptype, m, x, y, z, vx, vy, vz, potential, softening)[source]

Bases: object

ParticleSet class.

Creates a set particles of a particular type (stars, dark matter or gas) using masses, positions, velocities and potential energy.

Parameters

  • ptype (ParticleSetType) – Indicates if this set corresponds to stars, dark matter or gas.

  • m (Quantity) – Particle masses. Shape: (n,1). Default unit: M_sun

  • x (Quantity) – Positions. Shapes: (n,1). Default unit: kpc.

  • y (Quantity) – Positions. Shapes: (n,1). Default unit: kpc.

  • z (Quantity) – Positions. Shapes: (n,1). Default unit: kpc.

  • vx (Quantity) – Velocities. Shapes: (n,1). Default unit: km/s.

  • vy (Quantity) – Velocities. Shapes: (n,1). Default unit: km/s.

  • vz (Quantity) – Velocities. Shapes: (n,1). Default unit: km/s.

  • potential (Quantity, default value = 0) – Specific potential energy of particles. Shape: (n,1). Default unit: (km/s)**2.

  • softening (Quantity, default value = 0) – Softening radius of particles. Shape: (1,). Default unit: kpc.

  • kinetic_energy (Quantity) – Specific kinetic energy of particles. Shape: (n,1). Default unit: (km/s)**2.

  • total_energy (Quantity) – Specific total energy of particles. Shape: (n,1). Default unit: (km/s)**2.

  • Jx (Quantity) – Components of angular momentum of particles. Shapes: (n,1). Default units: kpc*km/s.

  • Jy (Quantity) – Components of angular momentum of particles. Shapes: (n,1). Default units: kpc*km/s.

  • Jz (Quantity) – Components of angular momentum of particles. Shapes: (n,1). Default units: kpc*km/s.

  • has_potential (bool.) – Indicates if the specific potential energy is computed.

  • arr (Instances of ArrayAccessor) – Access to the attributes (defined with uttrs) of the provided instance, and if they are of atropy.units.Quantity type it converts them into numpy.ndarray.

property angular_momentum_

Components of specific angular momentum in units of kpc*km/s.

to_dataframe(attributes=None)[source]

Convert to pandas data frame.

This method constructs a data frame with the particles and parameters of ParticleSet class.

Parameters

attributes (tuple, default value = None) – Dictionary keys of ParticleSet parameters used to create the data frame. If it’s None, the data frame is constructed from all the parameters of the ParticleSet class.

Returns

DataFrame – Data frame of the particles with the selected parameters.

Return type

pandas data frame

class galaxychop.data.Galaxy(stars, dark_matter, gas)[source]

Bases: object

Galaxy class.

Builds a galaxy object from a ParticleSet for each type of particle (stars, dark matter and gas).

Parameters

  • stars (ParticleSet) – Instance of ParticleSet with stars particles.

  • dark_matter (ParticleSet) – Instance of ParticleSet with dark matter particles.

  • gas (ParticleSet) – Instance of ParticleSet with gas particles.

has_potential_

Indicates if this Galaxy instance has the potential energy computed.

Type

bool

to_dataframe(*, ptypes=None, attributes=None)[source]

Convert to pandas data frame.

This method builds a data frame from the particles of the Galaxy.

Parameters

  • ptypes (tuple, default value = None) – Strings indicating the ParticleSetType to include. If it’s None, all particle types are included.

  • attributes (tuple, default value = None) – Dictionary keys of ParticleSet parameters used to create the data frame. If it’s None, the data frame is constructed from all the parameters of the ParticleSet class.

Returns

DataFrame – Data frame of Galaxy with selected particles and parameters.

Return type

pandas data frame

to_hdf5(path_or_stream, metadata=None, **kwargs)[source]

Shortcut to galaxychop.io.to_hdf5().

It is responsible for storing a galaxy in HDF5 format. The procedure only stores the attributes m, x, y, z, vx, vy and vz, since all the other attributes can be derived from these, and the softenings can be arbitrarily changed at the galaxy creation/reading process

Parameters

  • path_or_stream (str or file like.) – Path or file like objet to the h5 to store the galaxy.

  • metadata (dict or None (default None)) – Extra metadata to store in the h5 file.

  • kwargs – Extra arguments to the function astropy.io.misc.hdf5.write_table_hdf5()

property plot

Plot accessor.

property kinetic_energy_

Specific kinetic energy of stars, dark matter and gas particles.

Returns

tuple – (k_s, k_dm, k_g): Specific kinetic energy of stars, dark matter and gas respectively. Shape(n_s, n_dm, n_g). Unit: (km/s)**2

Return type

Quantity

Examples

This returns the specific kinetic energy of stars, dark matter and gas particles respectively.

>>> import galaxychop as gchop
>>> galaxy = gchop.Galaxy(...)
>>> k_s, k_dm, k_g = galaxy.kinetic_energy_
property potential_energy_

Specific potential energy of stars, dark matter and gas particles.

This property doesn’t compute the potential energy, only returns its value if it is already computed, i.e. has_potential_ is True. To compute the potential use the galaxychop.potential function.

Returns

tuple – (p_s, p_dm, p_g): Specific potential energy of stars, dark matter and gas respectively. Shape(n_s, n_dm, n_g). Unit: (km/s)**2

Return type

Quantity

Examples

This returns the specific potential energy of stars, dark matter and gas particles respectively.

>>> import galaxychop as gchop
>>> galaxy = gchop.Galaxy(...)
>>> galaxy_with_potential = gchop.potential(galaxy)
>>> p_s, p_dm, p_g = galaxy_with_potential.potential_energy_
property total_energy_

Specific total energy calculation.

Calculates the specific total energy of dark matter, star and gas particles.

Returns

tuple – (Etot_s, Etot_dm, Etot_g): Specific total energy of stars, dark matter and gas respectively. Shape(n_s, n_dm, n_g). Unit: (km/s)**2

Return type

Quantity

Examples

This returns the specific total energy of stars, dark matter and gas particles respectively.

>>> import galaxychop as gchop
>>> galaxy = gchop.Galaxy(...)
>>> E_s, E_dm, E_g = galaxy.total_energy_
property angular_momentum_

Specific angular momentum calculation.

Compute the specific angular momentum of stars, dark matter and gas particles.

Returns

tuple – (J_s, J_dm, J_g): Specific angular momentum of stars, dark matter and gas respectively. Shape(n_s, n_dm, n_g). Unit: (kpc * km / s)

Return type

Quantity

Examples

This returns the specific angular momentum of stars, dark matter and gas particles respectively.

>>> import galaxychop as gchop
>>> galaxy = gchop.Galaxy(...)
>>> J_s, J_dm, J_g = galaxy.angular_momentum_
galaxychop.data.galaxy_as_kwargs(galaxy)[source]

Galaxy init attributes as dictionary.

Parameters

galaxy (Galaxy) – Instance of Galaxy.

Returns

kwargs – Dictionary with galaxy attributes.

Return type

dict

galaxychop.data.mkgalaxy(m_s: numpy.ndarray, x_s: numpy.ndarray, y_s: numpy.ndarray, z_s: numpy.ndarray, vx_s: numpy.ndarray, vy_s: numpy.ndarray, vz_s: numpy.ndarray, m_dm: numpy.ndarray, x_dm: numpy.ndarray, y_dm: numpy.ndarray, z_dm: numpy.ndarray, vx_dm: numpy.ndarray, vy_dm: numpy.ndarray, vz_dm: numpy.ndarray, m_g: numpy.ndarray, x_g: numpy.ndarray, y_g: numpy.ndarray, z_g: numpy.ndarray, vx_g: numpy.ndarray, vy_g: numpy.ndarray, vz_g: numpy.ndarray, softening_s: float = 0.0, softening_dm: float = 0.0, softening_g: float = 0.0, potential_s: Optional[numpy.ndarray] = None, potential_dm: Optional[numpy.ndarray] = None, potential_g: Optional[numpy.ndarray] = None)[source]

Galaxy builder.

This function builds a galaxy object from a star, dark matter and gas ParticleSet.

Parameters

  • m_s (np.ndarray) – Star masses. Shape: (n,1).

  • x_s (np.ndarray) – Star positions. Shapes: (n,1).

  • y_s (np.ndarray) – Star positions. Shapes: (n,1).

  • z_s (np.ndarray) – Star positions. Shapes: (n,1).

  • vx_s (np.ndarray) – Star velocities. Shape: (n,1).

  • vy_s (np.ndarray) – Star velocities. Shape: (n,1).

  • vz_s (np.ndarray) – Star velocities. Shape: (n,1).

  • m_dm (np.ndarray) – Dark matter masses. Shape: (n,1).

  • x_dm (np.ndarray) – Dark matter positions. Shapes: (n,1).

  • y_dm (np.ndarray) – Dark matter positions. Shapes: (n,1).

  • z_dm (np.ndarray) – Dark matter positions. Shapes: (n,1).

  • vx_dm (np.ndarray) – Dark matter velocities. Shapes: (n,1).

  • vy_dm (np.ndarray) – Dark matter velocities. Shapes: (n,1).

  • vz_dm (np.ndarray) – Dark matter velocities. Shapes: (n,1).

  • m_g (np.ndarray) – Gas masses. Shape: (n,1).

  • x_g (np.ndarray) – Gas positions. Shapes: (n,1).

  • y_g (np.ndarray) – Gas positions. Shapes: (n,1).

  • z_g (np.ndarray) – Gas positions. Shapes: (n,1).

  • vx_g (np.ndarray) – Gas velocities. Shapes: (n,1).

  • vy_g (np.ndarray) – Gas velocities. Shapes: (n,1).

  • vz_g (np.ndarray) – Gas velocities. Shapes: (n,1).

  • potential_s (np.ndarray, default value = None) – Specific potential energy of star particles. Shape: (n,1).

  • potential_dm (np.ndarray, default value = None) – Specific potential energy of dark matter particles. Shape: (n,1).

  • potential_g (np.ndarray, default value = None) – Specific potential energy of gas particles. Shape: (n,1).

  • softening_s (float, default value = 0) – Softening radius of stellar particles. Shape: (1,).

  • softening_dm (float, default value = 0) – Softening radius of dark matter particles. Shape: (1,).

  • softening_g (float, default value = 0) – Softening radius of gas particles. Shape: (1,).

Returns

galaxy

Return type

Galaxy class object.