# -*- Mode: python; tab-width: 4; indent-tabs-mode:nil; coding:utf-8 -*-
# vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4
#
# MDAnalysis --- https://www.mdanalysis.org
# Copyright (c) 2006-2017 The MDAnalysis Development Team and contributors
# (see the file AUTHORS for the full list of names)
#
# Released under the Lesser GNU Public Licence, v2.1 or any higher version
#
# 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
#
# 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
#
"""Analysis building blocks --- :mod:`MDAnalysis.analysis.base`
============================================================
MDAnalysis provides building blocks for creating analysis classes. One can
think of each analysis class as a "tool" that performs a specific analysis over
the trajectory frames and stores the results in the tool.
Analysis classes are derived from :class:`AnalysisBase` by subclassing. This
inheritance provides a common workflow and API for users and makes many
additional features automatically available (such as frame selections and a
verbose progressbar). The important points for analysis classes are:
#. Analysis tools are Python classes derived from :class:`AnalysisBase`.
#. When instantiating an analysis, the :class:`Universe` or :class:`AtomGroup`
that the analysis operates on is provided together with any other parameters
that are kept fixed for the specific analysis.
#. The analysis is performed with :meth:`~AnalysisBase.run` method. It has a
common set of arguments such as being able to select the frames the analysis
is performed on. The `verbose` keyword argument enables additional output. A
progressbar is shown by default that also shows an estimate for the
remaining time until the end of the analysis.
#. Results are always stored in the attribute :attr:`AnalysisBase.results`,
which is an instance of :class:`Results`, a kind of dictionary that allows
allows item access via attributes. Each analysis class decides what and how
to store in :class:`Results` and needs to document it. For time series, the
:attr:`AnalysisBase.times` contains the time stamps of the analyzed frames.
Example of using a standard analysis tool
-----------------------------------------
For example, the :class:`MDAnalysis.analysis.rms.RMSD` performs a
root-mean-square distance analysis in the following way:
.. code-block:: python
import MDAnalysis as mda
from MDAnalysisTests.datafiles import TPR, XTC
from MDAnalysis.analysis import rms
u = mda.Universe(TPR, XTC)
# (2) instantiate analysis
rmsd = rms.RMSD(u, select='name CA')
# (3) the run() method can select frames in different ways
# run on all frames (with progressbar)
rmsd.run(verbose=True)
# or start, stop, and step can be used
rmsd.run(start=2, stop=8, step=2)
# a list of frames to run the analysis on can be passed
rmsd.run(frames=[0,2,3,6,9])
# a list of booleans the same length of the trajectory can be used
rmsd.run(frames=[True, False, True, True, False, False, True, False,
False, True])
# (4) analyze the results, e.g., plot
t = rmsd.times
y = rmsd.results.rmsd[:, 2] # RMSD at column index 2, see docs
import matplotlib.pyplot as plt
plt.plot(t, y)
plt.xlabel("time (ps)")
plt.ylabel("RMSD (Å)")
Writing new analysis tools
--------------------------
In order to write new analysis tools, derive a class from :class:`AnalysisBase`
and define at least the :meth:`_single_frame` method, as described in
:class:`AnalysisBase`.
.. SeeAlso::
The chapter `Writing your own trajectory analysis`_ in the *User Guide*
contains a step-by-step example for writing analysis tools with
:class:`AnalysisBase`.
.. _`Writing your own trajectory analysis`:
https://userguide.mdanalysis.org/stable/examples/analysis/custom_trajectory_analysis.html
If your analysis is operating independently on each frame, you might consider
making it **parallelizable** via adding a :meth:`get_supported_backends` method,
and appropriate aggregation function for each of its results. For example, if
you have your :meth:`_single_frame` method storing important values under
:attr:`self.results.timeseries`, you will write:
.. code-block:: python
class MyAnalysis(AnalysisBase):
_analysis_algorithm_is_parallelizable = True
@classmethod
def get_supported_backends(cls):
return ('serial', 'multiprocessing', 'dask',)
def _get_aggregator(self):
return ResultsGroup(lookup={'timeseries': ResultsGroup.ndarray_vstack})
See :mod:`MDAnalysis.analysis.results` for more on aggregating results.
.. SeeAlso::
:ref:`parallel-analysis`
Classes
-------
The :class:`MDAnalysis.results.Results` and :class:`AnalysisBase` classes
are the essential building blocks for almost all MDAnalysis tools in the
:mod:`MDAnalysis.analysis` module. They aim to be easily useable and
extendable.
:class:`AnalysisFromFunction` and the :func:`analysis_class` functions are
simple wrappers that make it even easier to create fully-featured analysis
tools if only the single-frame analysis function needs to be written.
"""
import inspect
import itertools
import logging
import warnings
from functools import partial
from typing import Iterable, Union
import numpy as np
from .. import coordinates
from ..core.groups import AtomGroup
from ..lib.log import ProgressBar
from .backends import BackendDask, BackendMultiprocessing, BackendSerial, BackendBase
from .results import Results, ResultsGroup
logger = logging.getLogger(__name__)
[docs]class AnalysisBase(object):
r"""Base class for defining multi-frame analysis
The class is designed as a template for creating multi-frame analyses.
This class will automatically take care of setting up the trajectory
reader for iterating, and it offers to show a progress meter.
Computed results are stored inside the :attr:`results` attribute.
To define a new Analysis, :class:`AnalysisBase` needs to be subclassed
and :meth:`_single_frame` must be defined. It is also possible to define
:meth:`_prepare` and :meth:`_conclude` for pre- and post-processing.
All results should be stored as attributes of the
:class:`MDAnalysis.analysis.results.Results` container.
Parameters
----------
trajectory : MDAnalysis.coordinates.base.ReaderBase
A trajectory Reader
verbose : bool, optional
Turn on more logging and debugging
Attributes
----------
times: numpy.ndarray
array of Timestep times. Only exists after calling
:meth:`AnalysisBase.run`
frames: numpy.ndarray
array of Timestep frame indices. Only exists after calling
:meth:`AnalysisBase.run`
results: :class:`Results`
results of calculation are stored after call
to :meth:`AnalysisBase.run`
Example
-------
.. code-block:: python
from MDAnalysis.analysis.base import AnalysisBase
class NewAnalysis(AnalysisBase):
def __init__(self, atomgroup, parameter, **kwargs):
super(NewAnalysis, self).__init__(atomgroup.universe.trajectory,
**kwargs)
self._parameter = parameter
self._ag = atomgroup
def _prepare(self):
# OPTIONAL
# Called before iteration on the trajectory has begun.
# Data structures can be set up at this time
self.results.example_result = []
def _single_frame(self):
# REQUIRED
# Called after the trajectory is moved onto each new frame.
# store an example_result of `some_function` for a single frame
self.results.example_result.append(some_function(self._ag,
self._parameter))
def _conclude(self):
# OPTIONAL
# Called once iteration on the trajectory is finished.
# Apply normalisation and averaging to results here.
self.results.example_result = np.asarray(self.example_result)
self.results.example_result /= np.sum(self.result)
Afterwards the new analysis can be run like this
.. code-block:: python
import MDAnalysis as mda
from MDAnalysisTests.datafiles import PSF, DCD
u = mda.Universe(PSF, DCD)
na = NewAnalysis(u.select_atoms('name CA'), 35)
na.run(start=10, stop=20)
print(na.results.example_result)
# results can also be accessed by key
print(na.results["example_result"])
.. versionchanged:: 1.0.0
Support for setting `start`, `stop`, and `step` has been removed. These
should now be directly passed to :meth:`AnalysisBase.run`.
.. versionchanged:: 2.0.0
Added :attr:`results`
.. versionchanged:: 2.8.0
Added ability to run analysis in parallel using either a
built-in backend (`multiprocessing` or `dask`) or a custom
`backends.BackendBase` instance with an implemented `apply` method
that is used to run the computations.
"""
[docs] @classmethod
def get_supported_backends(cls):
"""Tuple with backends supported by the core library for a given class.
User can pass either one of these values as ``backend=...`` to
:meth:`run()` method, or a custom object that has ``apply`` method
(see documentation for :meth:`run()`):
- 'serial': no parallelization
- 'multiprocessing': parallelization using `multiprocessing.Pool`
- 'dask': parallelization using `dask.delayed.compute()`. Requires
installation of `mdanalysis[dask]`
If you want to add your own backend to an existing class, pass a
:class:`backends.BackendBase` subclass (see its documentation to learn
how to implement it properly), and specify ``unsupported_backend=True``.
Returns
-------
tuple
names of built-in backends that can be used in :meth:`run(backend=...)`
.. versionadded:: 2.8.0
"""
return ("serial",)
# class authors: override _analysis_algorithm_is_parallelizable
# in derived classes and only set to True if you have confirmed
# that your algorithm works reliably when parallelized with
# the split-apply-combine approach (see docs)
_analysis_algorithm_is_parallelizable = False
@property
def parallelizable(self):
"""Boolean mark showing that a given class can be parallelizable with
split-apply-combine procedure. Namely, if we can safely distribute
:meth:`_single_frame` to multiple workers and then combine them with a
proper :meth:`_conclude` call. If set to ``False``, no backends except
for ``serial`` are supported.
.. note:: If you want to check parallelizability of the whole class, without
explicitly creating an instance of the class, see
:attr:`_analysis_algorithm_is_parallelizable`. Note that you
setting it to other value will break things if the algorithm
behind the analysis is not trivially parallelizable.
Returns
-------
bool
if a given ``AnalysisBase`` subclass instance
is parallelizable with split-apply-combine, or not
.. versionadded:: 2.8.0
"""
return self._analysis_algorithm_is_parallelizable
def __init__(self, trajectory, verbose=False, **kwargs):
self._trajectory = trajectory
self._verbose = verbose
self.results = Results()
[docs] def _define_run_frames(self, trajectory,
start=None, stop=None, step=None, frames=None
) -> Union[slice, np.ndarray]:
"""Defines limits for the whole run, as passed by self.run() arguments
Parameters
----------
trajectory : mda.Reader
a trajectory Reader
start : int, optional
start frame of analysis, by default None
stop : int, optional
stop frame of analysis, by default None
step : int, optional
number of frames to skip between each analysed frame, by default None
frames : array_like, optional
array of integers or booleans to slice trajectory; cannot be
combined with ``start``, ``stop``, ``step``; by default None
Returns
-------
Union[slice, np.ndarray]
Appropriate slicer for the trajectory that would give correct iteraction
order via trajectory[slicer]
Raises
------
ValueError
if *both* `frames` and at least one of ``start``, ``stop``, or ``step``
is provided (i.e. set to not ``None`` value).
.. versionadded:: 2.8.0
"""
self._trajectory = trajectory
if frames is not None:
if not all(opt is None for opt in [start, stop, step]):
raise ValueError("start/stop/step cannot be combined with frames")
slicer = frames
else:
start, stop, step = trajectory.check_slice_indices(start, stop, step)
slicer = slice(start, stop, step)
self.start, self.stop, self.step = start, stop, step
return slicer
[docs] def _prepare_sliced_trajectory(self, slicer: Union[slice, np.ndarray]):
"""Prepares sliced trajectory for use in subsequent parallel computations:
namely, assigns self._sliced_trajectory and its appropriate attributes,
self.n_frames, self.frames and self.times.
Parameters
----------
slicer : Union[slice, np.ndarray]
appropriate slicer for the trajectory
.. versionadded:: 2.8.0
"""
self._sliced_trajectory = self._trajectory[slicer]
self.n_frames = len(self._sliced_trajectory)
self.frames = np.zeros(self.n_frames, dtype=int)
self.times = np.zeros(self.n_frames)
[docs] def _setup_frames(self, trajectory, start=None, stop=None, step=None, frames=None):
"""Pass a Reader object and define the desired iteration pattern
through the trajectory
Parameters
----------
trajectory : mda.Reader
A trajectory Reader
start : int, optional
start frame of analysis
stop : int, optional
stop frame of analysis
step : int, optional
number of frames to skip between each analysed frame
frames : array_like, optional
array of integers or booleans to slice trajectory; cannot be
combined with ``start``, ``stop``, ``step``
.. versionadded:: 2.2.0
Raises
------
ValueError
if *both* `frames` and at least one of ``start``, ``stop``, or
``frames`` is provided (i.e., set to another value than ``None``)
.. versionchanged:: 1.0.0
Added .frames and .times arrays as attributes
.. versionchanged:: 2.2.0
Added ability to iterate through trajectory by passing a list of
frame indices in the `frames` keyword argument
.. versionchanged:: 2.8.0
Split function into two: :meth:`_define_run_frames` and
:meth:`_prepare_sliced_trajectory`: first one defines the limits
for the whole run and is executed once during :meth:`run` in
:meth:`_setup_frames`, second one prepares sliced trajectory for
each of the workers and gets executed twice: one time in
:meth:`_setup_frames` for the whole trajectory, second time in
:meth:`_compute` for each of the computation groups.
"""
slicer = self._define_run_frames(trajectory, start, stop, step, frames)
self._prepare_sliced_trajectory(slicer)
[docs] def _single_frame(self):
"""Calculate data from a single frame of trajectory
Don't worry about normalising, just deal with a single frame.
Attributes accessible during your calculations:
- ``self._frame_index``: index of the frame in results array
- ``self._ts`` -- Timestep instance
- ``self._sliced_trajectory`` -- trajectory that you're iterating over
- ``self.results`` -- :class:`MDAnalysis.analysis.results.Results` instance
holding run results initialized in :meth:`_prepare`.
"""
raise NotImplementedError("Only implemented in child classes")
[docs] def _prepare(self):
"""
Set things up before the analysis loop begins.
Notes
-----
``self.results`` is initialized already in :meth:`self.__init__` with an
empty instance of :class:`MDAnalysis.analysis.results.Results` object.
You can still call your attributes as if they were usual ones,
``Results`` just keeps track of that to be able to run a proper
aggregation after a parallel run, if necessary.
"""
pass # pylint: disable=unnecessary-pass
[docs] def _conclude(self):
"""Finalize the results you've gathered.
Called at the end of the :meth:`run` method to finish everything up.
Notes
-----
Aggregation of results from individual workers happens in
:meth:`self.run()`, so here you have to implement everything as if you
had a non-parallel run. If you want to enable proper aggregation for
parallel runs for you analysis class, implement ``self._get_aggregator``
and check :mod:`MDAnalysis.analysis.results` for how to use it.
"""
pass # pylint: disable=unnecessary-pass
[docs] def _compute(self, indexed_frames: np.ndarray,
verbose: bool = None,
*, progressbar_kwargs={}) -> "AnalysisBase":
"""Perform the calculation on a balanced slice of frames
that have been setup prior to that using _setup_computation_groups()
Parameters
----------
indexed_frames : np.ndarray
np.ndarray of (n, 2) shape, where first column is frame iteration
indices and second is frame numbers
verbose : bool, optional
Turn on verbosity
progressbar_kwargs : dict, optional
ProgressBar keywords with custom parameters regarding progress bar
position, etc; see :class:`MDAnalysis.lib.log.ProgressBar`
for full list.
.. versionadded:: 2.8.0
"""
logger.info("Choosing frames to analyze")
# if verbose unchanged, use class default
verbose = getattr(self, "_verbose", False) if verbose is None else verbose
frames = indexed_frames[:, 1]
logger.info("Starting preparation")
self._prepare_sliced_trajectory(slicer=frames)
self._prepare()
if len(frames) == 0: # if `frames` were empty in `run` or `stop=0`
return self
for idx, ts in enumerate(ProgressBar(
self._sliced_trajectory,
verbose=verbose,
**progressbar_kwargs)):
self._frame_index = idx # accessed later by subclasses
self._ts = ts
self.frames[idx] = ts.frame
self.times[idx] = ts.time
self._single_frame()
logger.info("Finishing up")
return self
[docs] def _setup_computation_groups(
self, n_parts: int,
start: int = None, stop: int = None, step: int = None,
frames: Union[slice, np.ndarray] = None
) -> list[np.ndarray]:
"""
Splits the trajectory frames, defined by ``start/stop/step`` or
``frames``, into ``n_parts`` even groups, preserving their indices.
Parameters
----------
n_parts : int
number of parts to split the workload into
start : int, optional
start frame
stop : int, optional
stop frame
step : int, optional
step size for analysis (1 means to read every frame)
frames : array_like, optional
array of integers or booleans to slice trajectory; ``frames`` can
only be used *instead* of ``start``, ``stop``, and ``step``. Setting
*both* ``frames`` and at least one of ``start``, ``stop``, ``step``
to a non-default value will raise a :exc:`ValueError`.
Raises
------
ValueError
if *both* ``frames`` and at least one of ``start``, ``stop``, or
``frames`` is provided (i.e., set to another value than ``None``)
Returns
-------
computation_groups : list[np.ndarray]
list of (n, 2) shaped np.ndarrays with frame indices and numbers
.. versionadded:: 2.8.0
"""
if frames is None:
start, stop, step = self._trajectory.check_slice_indices(start, stop, step)
used_frames = np.arange(start, stop, step)
elif not all(opt is None for opt in [start, stop, step]):
raise ValueError("start/stop/step cannot be combined with frames")
else:
used_frames = frames
if all(isinstance(obj, bool) for obj in used_frames):
arange = np.arange(len(used_frames))
used_frames = arange[used_frames]
# similar to list(enumerate(frames))
enumerated_frames = np.vstack([np.arange(len(used_frames)), used_frames]).T
if len(enumerated_frames) == 0:
return [np.empty((0, 2), dtype=np.int64)]
elif len(enumerated_frames) < n_parts:
# Issue #4685
n_parts = len(enumerated_frames)
warnings.warn(f"Set `n_parts` to {n_parts} to match the total "
"number of frames being analyzed")
return np.array_split(enumerated_frames, n_parts)
[docs] def run(
self,
start: int = None,
stop: int = None,
step: int = None,
frames: Iterable = None,
verbose: bool = None,
n_workers: int = None,
n_parts: int = None,
backend: Union[str, BackendBase] = None,
*,
unsupported_backend: bool = False,
progressbar_kwargs=None,
):
"""Perform the calculation
Parameters
----------
start : int, optional
start frame of analysis
stop : int, optional
stop frame of analysis
step : int, optional
number of frames to skip between each analysed frame
frames : array_like, optional
array of integers or booleans to slice trajectory; ``frames`` can
only be used *instead* of ``start``, ``stop``, and ``step``. Setting
*both* ``frames`` and at least one of ``start``, ``stop``, ``step``
to a non-default value will raise a :exc:`ValueError`.
.. versionadded:: 2.2.0
verbose : bool, optional
Turn on verbosity
progressbar_kwargs : dict, optional
ProgressBar keywords with custom parameters regarding progress bar
position, etc; see :class:`MDAnalysis.lib.log.ProgressBar`
for full list. Available only for ``backend='serial'``
backend : Union[str, BackendBase], optional
By default, performs calculations in a serial fashion.
Otherwise, user can choose a backend: ``str`` is matched to a
builtin backend (one of ``serial``, ``multiprocessing`` and
``dask``), or a :class:`MDAnalysis.analysis.results.BackendBase`
subclass.
.. versionadded:: 2.8.0
n_workers : int
positive integer with number of workers (processes, in case of
built-in backends) to split the work between
.. versionadded:: 2.8.0
n_parts : int, optional
number of parts to split computations across. Can be more than
number of workers.
.. versionadded:: 2.8.0
unsupported_backend : bool, optional
if you want to run your custom backend on a parallelizable class
that has not been tested by developers, by default False
.. versionadded:: 2.8.0
.. versionchanged:: 2.2.0
Added ability to analyze arbitrary frames by passing a list of
frame indices in the `frames` keyword argument.
.. versionchanged:: 2.5.0
Add `progressbar_kwargs` parameter,
allowing to modify description, position etc of tqdm progressbars
.. versionchanged:: 2.8.0
Introduced ``backend``, ``n_workers``, ``n_parts`` and
``unsupported_backend`` keywords, and refactored the method logic to
support parallelizable execution.
"""
# default to serial execution
backend = "serial" if backend is None else backend
progressbar_kwargs = {} if progressbar_kwargs is None else progressbar_kwargs
if ((progressbar_kwargs or verbose) and
not (backend == "serial" or
isinstance(backend, BackendSerial))):
raise ValueError("Can not display progressbar with non-serial backend")
# if number of workers not specified, try getting the number from
# the backend instance if possible, or set to 1
if n_workers is None:
n_workers = (
backend.n_workers
if isinstance(backend, BackendBase) and hasattr(backend, "n_workers")
else 1
)
# set n_parts and check that is has a reasonable value
n_parts = n_workers if n_parts is None else n_parts
# do this as early as possible to check client parameters
# before any computations occur
executor = self._configure_backend(
backend=backend,
n_workers=n_workers,
unsupported_backend=unsupported_backend)
if (
hasattr(executor, "n_workers") and n_parts < executor.n_workers
): # using executor's value here for non-default executors
warnings.warn((
f"Analysis not making use of all workers: "
f"{executor.n_workers=} is greater than {n_parts=}"))
# start preparing the run
worker_func = partial(
self._compute,
progressbar_kwargs=progressbar_kwargs,
verbose=verbose)
self._setup_frames(
trajectory=self._trajectory,
start=start, stop=stop, step=step, frames=frames)
computation_groups = self._setup_computation_groups(
start=start, stop=stop, step=step, frames=frames, n_parts=n_parts
)
# get all results from workers in other processes.
# we need `AnalysisBase` classes
# since they hold `frames`, `times` and `results` attributes
remote_objects: list["AnalysisBase"] = executor.apply(
worker_func, computation_groups)
self.frames = np.hstack([obj.frames for obj in remote_objects])
self.times = np.hstack([obj.times for obj in remote_objects])
# aggregate results from results obtained in remote workers
remote_results = [obj.results for obj in remote_objects]
results_aggregator = self._get_aggregator()
self.results = results_aggregator.merge(remote_results)
self._conclude()
return self
[docs] def _get_aggregator(self) -> ResultsGroup:
"""Returns a default aggregator that takes entire results
if there is a single object, and raises ValueError otherwise
Returns
-------
ResultsGroup
aggregating object
.. versionadded:: 2.8.0
"""
return ResultsGroup(lookup=None)
[docs]class AnalysisFromFunction(AnalysisBase):
r"""Create an :class:`AnalysisBase` from a function working on AtomGroups
Parameters
----------
function : callable
function to evaluate at each frame
trajectory : MDAnalysis.coordinates.Reader, optional
trajectory to iterate over. If ``None`` the first AtomGroup found in
args and kwargs is used as a source for the trajectory.
*args : list
arguments for `function`
**kwargs : dict
arguments for `function` and :class:`AnalysisBase`
Attributes
----------
results.frames : numpy.ndarray
simulation frames used in analysis
results.times : numpy.ndarray
simulation times used in analysis
results.timeseries : numpy.ndarray
Results for each frame of the wrapped function,
stored after call to :meth:`AnalysisFromFunction.run`.
Raises
------
ValueError
if `function` has the same `kwargs` as :class:`AnalysisBase`
Example
-------
.. code-block:: python
def rotation_matrix(mobile, ref):
return mda.analysis.align.rotation_matrix(mobile, ref)[0]
rot = AnalysisFromFunction(rotation_matrix, trajectory,
mobile, ref).run()
print(rot.results.timeseries)
.. versionchanged:: 1.0.0
Support for directly passing the `start`, `stop`, and `step` arguments
has been removed. These should instead be passed to
:meth:`AnalysisFromFunction.run`.
.. versionchanged:: 2.0.0
Former :attr:`results` are now stored as :attr:`results.timeseries`
.. versionchanged:: 2.8.0
Added :meth:`get_supported_backends()`, introducing 'serial', 'multiprocessing'
and 'dask' backends.
"""
_analysis_algorithm_is_parallelizable = True
[docs] @classmethod
def get_supported_backends(cls):
return ("serial", "multiprocessing", "dask")
def __init__(self, function, trajectory=None, *args, **kwargs):
if (trajectory is not None) and (not isinstance(
trajectory, coordinates.base.ProtoReader)):
args = (trajectory,) + args
trajectory = None
if trajectory is None:
# all possible places to find trajectory
for arg in itertools.chain(args, kwargs.values()):
if isinstance(arg, AtomGroup):
trajectory = arg.universe.trajectory
break
if trajectory is None:
raise ValueError("Couldn't find a trajectory")
self.function = function
self.args = args
self.kwargs = kwargs
super(AnalysisFromFunction, self).__init__(trajectory)
[docs] def _prepare(self):
self.results.timeseries = []
[docs] def _get_aggregator(self):
return ResultsGroup({"timeseries": ResultsGroup.flatten_sequence})
[docs] def _single_frame(self):
self.results.timeseries.append(self.function(*self.args, **self.kwargs))
[docs] def _conclude(self):
self.results.frames = self.frames
self.results.times = self.times
self.results.timeseries = np.asarray(self.results.timeseries)
[docs]def analysis_class(function):
r"""Transform a function operating on a single frame to an
:class:`AnalysisBase` class.
Parameters
----------
function : callable
function to evaluate at each frame
Attributes
----------
results.frames : numpy.ndarray
simulation frames used in analysis
results.times : numpy.ndarray
simulation times used in analysis
results.timeseries : numpy.ndarray
Results for each frame of the wrapped function,
stored after call to :meth:`AnalysisFromFunction.run`.
Raises
------
ValueError
if `function` has the same `kwargs` as :class:`AnalysisBase`
Examples
--------
For use in a library, we recommend the following style
.. code-block:: python
def rotation_matrix(mobile, ref):
return mda.analysis.align.rotation_matrix(mobile, ref)[0]
RotationMatrix = analysis_class(rotation_matrix)
It can also be used as a decorator
.. code-block:: python
@analysis_class
def RotationMatrix(mobile, ref):
return mda.analysis.align.rotation_matrix(mobile, ref)[0]
rot = RotationMatrix(u.trajectory, mobile, ref).run(step=2)
print(rot.results.timeseries)
.. versionchanged:: 2.0.0
Former :attr:`results` are now stored as :attr:`results.timeseries`
"""
class WrapperClass(AnalysisFromFunction):
def __init__(self, trajectory=None, *args, **kwargs):
super(WrapperClass, self).__init__(function, trajectory, *args, **kwargs)
@classmethod
def get_supported_backends(cls):
return ("serial", "dask")
return WrapperClass
[docs]def _filter_baseanalysis_kwargs(function, kwargs):
"""
Create two dictionaries with `kwargs` separated for `function` and
:class:`AnalysisBase`
Parameters
----------
function : callable
function to be called
kwargs : dict
keyword argument dictionary
Returns
-------
base_args : dict
dictionary of AnalysisBase kwargs
kwargs : dict
kwargs without AnalysisBase kwargs
Raises
------
ValueError
if `function` has the same `kwargs` as :class:`AnalysisBase`
"""
try:
# pylint: disable=deprecated-method
base_argspec = inspect.getfullargspec(AnalysisBase.__init__)
except AttributeError:
# pylint: disable=deprecated-method
base_argspec = inspect.getargspec(AnalysisBase.__init__)
n_base_defaults = len(base_argspec.defaults)
base_kwargs = {
name: val
for name, val in zip(base_argspec.args[-n_base_defaults:],
base_argspec.defaults)
}
try:
# pylint: disable=deprecated-method
argspec = inspect.getfullargspec(function)
except AttributeError:
# pylint: disable=deprecated-method
argspec = inspect.getargspec(function)
for base_kw in base_kwargs.keys():
if base_kw in argspec.args:
raise ValueError(
"argument name '{}' clashes with AnalysisBase argument."
"Now allowed are: {}".format(base_kw, base_kwargs.keys())
)
base_args = {}
for argname, default in base_kwargs.items():
base_args[argname] = kwargs.pop(argname, default)
return base_args, kwargs