yt.data_objects.particle_trajectories module

class yt.data_objects.particle_trajectories.ParticleTrajectories(outputs, indices, fields=None, suppress_logging=False, ptype=None)

Bases: object

A collection of particle trajectories in time over a series of datasets.

Parameters:

• outputs (DatasetSeries) – DatasetSeries object from which to draw the particles.

• indices (array_like) – An integer array of particle indices whose trajectories we want to track. If they are not sorted they will be sorted.

• fields (list of strings, optional) – A set of fields that is retrieved when the trajectory collection is instantiated. Default: None (will default to the fields ‘particle_position_x’, ‘particle_position_y’, ‘particle_position_z’)

• suppress_logging (boolean) – Suppress yt’s logging when iterating over the simulation time series. Default: False

• ptype (str, optional) – Only use this particle type. Default: None, which uses all particle type.

Examples

>>> my_fns = glob.glob("orbit_hdf5_chk_00[0-9][0-9]")
>>> my_fns.sort()
>>> fields = [
...     ("all", "particle_position_x"),
...     ("all", "particle_position_y"),
...     ("all", "particle_position_z"),
...     ("all", "particle_velocity_x"),
...     ("all", "particle_velocity_y"),
...     ("all", "particle_velocity_z"),
... ]
>>> ds = load(my_fns[0])
>>> init_sphere = ds.sphere(ds.domain_center, (0.5, "unitary"))
>>> indices = init_sphere["all", "particle_index"].astype("int64")
>>> ts = DatasetSeries(my_fns)
>>> trajs = ts.particle_trajectories(indices, fields=fields)
>>> for t in trajs:
...     print(
...         t["all", "particle_velocity_x"].max(),
...         t["all", "particle_velocity_x"].min(),
...     )

add_fields(fields)

Add a list of fields to an existing trajectory

Parameters:

fields (list of strings) – A list of fields to be added to the current trajectory collection.

Examples

>>> trajs = ParticleTrajectories(my_fns, indices)
>>> trajs.add_fields([("all", "particle_mass"), ("all", "particle_gpot")])

has_key(key)

keys()

trajectory_from_index(index)

Retrieve a single trajectory corresponding to a specific particle index

Parameters:

index (int) – This defines which particle trajectory from the ParticleTrajectories object will be returned.

Returns:

• A dictionary corresponding to the particle’s trajectory and the

• fields along that trajectory

Examples

>>> import matplotlib.pyplot as plt
>>> trajs = ParticleTrajectories(my_fns, indices)
>>> traj = trajs.trajectory_from_index(indices[0])
>>> plt.plot(
...     traj["all", "particle_time"],
...     traj["all", "particle_position_x"],
...     "-x",
... )
>>> plt.savefig("orbit")

write_out(filename_base)

Write out particle trajectories to tab-separated ASCII files (one for each trajectory) with the field names in the file header. Each file is named with a basename and the index number.

Parameters:

filename_base (string) – The prefix for the outputted ASCII files.

Examples

>>> trajs = ParticleTrajectories(my_fns, indices)
>>> trajs.write_out("orbit_trajectory")

write_out_h5(filename)

Write out all the particle trajectories to a single HDF5 file that contains the indices, the times, and the 2D array for each field individually

Parameters:

filename (string) – The output filename for the HDF5 file

Examples

>>> trajs = ParticleTrajectories(my_fns, indices)
>>> trajs.write_out_h5("orbit_trajectories")