# 7.24. TRZ trajectory I/O — `MDAnalysis.coordinates.TRZ`

Classes to read IBIsCO / YASP TRZ binary trajectories, including coordinates, velocities and more (see attributes of the `Timestep`).

Data are read and written in binary representation but because this depends on the machine hardware architecture, MDAnalysis always reads and writes TRZ trajectories in little-endian byte order.

## 7.24.1. Classes

class MDAnalysis.coordinates.TRZ.TRZReader(trzfilename, n_atoms=None, **kwargs)

  Reads an IBIsCO or YASP trajectory file

  ts

    `Timestep` object containing coordinates of current frame

    Type:

      timestep.Timestep

  Note

  Binary TRZ trajectories are always assumed to be written in little-endian byte order and are read as such.

  Changed in version 0.11.0: Frames now 0-based instead of 1-based. Extra data (Temperature, Energies, Pressures, etc) now read into ts.data dictionary. Now passes a weakref of self to ts (ts._reader).

  Changed in version 1.0.1: Now checks for the correct n_atoms on reading and can raise `ValueError`.

  Changed in version 2.1.0: TRZReader now returns a default `dt` of 1.0 when it cannot be obtained from the difference between two frames.

  Changed in version 2.3.0: _frame attribute moved to ts.data dictionary.

  Deprecated since version 2.7.0: The TRZ Reader and Writer are deprecated as of version 2.7.0 and will be removed in version 3.0.0.

  Creates a TRZ Reader

  Parameters:

    - trzfilename (str) – name of input file

    - n_atoms (int) – number of atoms in trajectory, must be taken from topology file!

    - convert_units (bool (optional)) – converts units to MDAnalysis defaults

  Raises:

    ValueError – If n_atoms or the number of atoms in the topology file do not match the number of atoms in the trajectory.

  Writer(filename, n_atoms=None)

    A trajectory writer with the same properties as this trajectory.

  close()

    Close trz file if it was open

  property delta

    MD integration timestep

  property n_atoms

    Number of atoms in a frame

  property n_frames

    Total number of frames in a trajectory

  open_trajectory()

    Open the trajectory file

  property skip_timestep

    Timesteps between trajectory frames

  units = {'length': 'nm', 'time': 'ps', 'velocity': 'nm/ps'}

    dict with units of of time and length (and velocity, force, … for formats that support it)

class MDAnalysis.coordinates.TRZ.TRZWriter(filename, n_atoms, title='TRZ', convert_units=True)

  Writes a TRZ format trajectory.

  Note

  Binary TRZ trajectories are always written in little-endian byte order.

  Deprecated since version 2.7.0: The TRZ Reader and Writer are deprecated as of version 2.7.0 and will be removed in version 3.0.0.

  Create a TRZWriter

  Parameters:

    - filename (str) – name of output file

    - n_atoms (int) – number of atoms in trajectory

    - title (str (optional)) – title of the trajectory; the title must be 80 characters or shorter, a longer title raises a ValueError exception.

    - convert_units (bool (optional)) – units are converted to the MDAnalysis base format; [`True`]

  close()

    Close if it was open

  units = {'length': 'nm', 'time': 'ps', 'velocity': 'nm/ps'}

    dict with units of of time and length (and velocity, force, … for formats that support it)