Source code for MDAnalysis.transformations.rotate
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# Please cite your use of MDAnalysis in published work:
#
# R. J. Gowers, M. Linke, J. Barnoud, T. J. E. Reddy, M. N. Melo, S. L. Seyler,
# D. L. Dotson, J. Domanski, S. Buchoux, I. M. Kenney, and O. Beckstein.
# MDAnalysis: A Python package for the rapid analysis of molecular dynamics
# simulations. In S. Benthall and S. Rostrup editors, Proceedings of the 15th
# Python in Science Conference, pages 102-109, Austin, TX, 2016. SciPy.
# doi: 10.25080/majora-629e541a-00e
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# N. Michaud-Agrawal, E. J. Denning, T. B. Woolf, and O. Beckstein.
# MDAnalysis: A Toolkit for the Analysis of Molecular Dynamics Simulations.
# J. Comput. Chem. 32 (2011), 2319--2327, doi:10.1002/jcc.21787
#
"""\
Trajectory rotation --- :mod:`MDAnalysis.transformations.rotate`
================================================================
Rotates the coordinates by a given angle arround an axis formed by a direction
and a point.
.. autoclass:: rotateby
"""
import numpy as np
from functools import partial
from ..lib.transformations import rotation_matrix
from ..lib.util import get_weights
from .base import TransformationBase
[docs]class rotateby(TransformationBase):
'''
Rotates the trajectory by a given angle on a given axis. The axis is defined by
the user, combining the direction vector and a point. This point can be the center
of geometry or the center of mass of a user defined AtomGroup, or an array defining
custom coordinates.
Note
----
``max_threads`` is set to 1 for this transformation
with which it performs better.
Examples
--------
e.g. rotate the coordinates by 90 degrees on a axis formed by the [0,0,1] vector and
the center of geometry of a given AtomGroup:
.. code-block:: python
from MDAnalysis import transformations
ts = u.trajectory.ts
angle = 90
ag = u.atoms
d = [0,0,1]
rotated = transformations.rotate.rotateby(angle, direction=d, ag=ag)(ts)
e.g. rotate the coordinates by a custom axis:
.. code-block:: python
from MDAnalysis import transformations
ts = u.trajectory.ts
angle = 90
p = [1,2,3]
d = [0,0,1]
rotated = transformations.rotate.rotateby(angle, direction=d, point=p)(ts)
Parameters
----------
angle: float
rotation angle in degrees
direction: array-like
vector that will define the direction of a custom axis of rotation from the
provided point. Expected shapes are (3, ) or (1, 3).
ag: AtomGroup, optional
use the weighted center of an AtomGroup as the point from where the rotation axis
will be defined. If no AtomGroup is given, the `point` argument becomes mandatory
point: array-like, optional
list of the coordinates of the point from where a custom axis of rotation will
be defined. Expected shapes are (3, ) or (1, 3). If no point is given, the
`ag` argument becomes mandatory.
weights: {"mass", ``None``} or array_like, optional
define the weights of the atoms when calculating the center of the AtomGroup.
With ``"mass"`` uses masses as weights; with ``None`` weigh each atom equally.
If a float array of the same length as `ag` is provided, use each element of
the `array_like` as a weight for the corresponding atom in `ag`. Default is
None.
wrap: bool, optional
If `True`, all the atoms from the given AtomGroup will be moved to the unit cell
before calculating the center of mass or geometry. Default is `False`, no changes
to the atom coordinates are done before calculating the center of the AtomGroup.
Returns
-------
MDAnalysis.coordinates.timestep.Timestep
Warning
-------
Wrapping/unwrapping the trajectory or performing PBC corrections may not be possible
after rotating the trajectory.
.. versionchanged:: 2.0.0
The transformation was changed from a function/closure to a class
with ``__call__``.
.. versionchanged:: 2.0.0
The transformation was changed to inherit from the base class for
limiting threads and checking if it can be used in parallel analysis.
'''
def __init__(self,
angle,
direction,
point=None,
ag=None,
weights=None,
wrap=False,
max_threads=1,
parallelizable=True):
super().__init__(max_threads=max_threads,
parallelizable=parallelizable)
self.angle = angle
self.direction = direction
self.point = point
self.ag = ag
self.weights = weights
self.wrap = wrap
self.angle = np.deg2rad(self.angle)
try:
self.direction = np.asarray(self.direction, np.float32)
if self.direction.shape != (3, ) and \
self.direction.shape != (1, 3):
raise ValueError('{} is not a valid direction'
.format(self.direction))
self.direction = self.direction.reshape(3, )
except ValueError:
raise ValueError(f'{self.direction} is not a valid direction') \
from None
if self.point is not None:
self.point = np.asarray(self.point, np.float32)
if self.point.shape != (3, ) and self.point.shape != (1, 3):
raise ValueError('{} is not a valid point'.format(self.point))
self.point = self.point.reshape(3, )
elif self.ag:
try:
self.atoms = self.ag.atoms
except AttributeError:
raise ValueError(f'{self.ag} is not an AtomGroup object') \
from None
else:
try:
self.weights = get_weights(self.atoms,
weights=self.weights)
except (ValueError, TypeError):
errmsg = ("weights must be {'mass', None} or an iterable "
"of the same size as the atomgroup.")
raise TypeError(errmsg) from None
self.center_method = partial(self.atoms.center,
self.weights,
wrap=self.wrap)
else:
raise ValueError('A point or an AtomGroup must be specified')
def _transform(self, ts):
if self.point is None:
position = self.center_method()
else:
position = self.point
matrix = rotation_matrix(self.angle, self.direction, position)
rotation = matrix[:3, :3].T
translation = matrix[:3, 3]
ts.positions = np.dot(ts.positions, rotation)
ts.positions += translation
return ts