192 lines
6.2 KiB
Python
192 lines
6.2 KiB
Python
import scipy._lib.uarray as ua
|
|
from . import _fftlog
|
|
from . import _pocketfft
|
|
|
|
|
|
class _ScipyBackend:
|
|
"""The default backend for fft calculations
|
|
|
|
Notes
|
|
-----
|
|
We use the domain ``numpy.scipy`` rather than ``scipy`` because ``uarray``
|
|
treats the domain as a hierarchy. This means the user can install a single
|
|
backend for ``numpy`` and have it implement ``numpy.scipy.fft`` as well.
|
|
"""
|
|
__ua_domain__ = "numpy.scipy.fft"
|
|
|
|
@staticmethod
|
|
def __ua_function__(method, args, kwargs):
|
|
|
|
fn = getattr(_pocketfft, method.__name__, None)
|
|
if fn is None:
|
|
fn = getattr(_fftlog, method.__name__, None)
|
|
if fn is None:
|
|
return NotImplemented
|
|
return fn(*args, **kwargs)
|
|
|
|
|
|
_named_backends = {
|
|
'scipy': _ScipyBackend,
|
|
}
|
|
|
|
|
|
def _backend_from_arg(backend):
|
|
"""Maps strings to known backends and validates the backend"""
|
|
|
|
if isinstance(backend, str):
|
|
try:
|
|
backend = _named_backends[backend]
|
|
except KeyError as e:
|
|
raise ValueError('Unknown backend {}'.format(backend)) from e
|
|
|
|
if backend.__ua_domain__ != 'numpy.scipy.fft':
|
|
raise ValueError('Backend does not implement "numpy.scipy.fft"')
|
|
|
|
return backend
|
|
|
|
|
|
def set_global_backend(backend, coerce=False, only=False, try_last=False):
|
|
"""Sets the global fft backend
|
|
|
|
This utility method replaces the default backend for permanent use. It
|
|
will be tried in the list of backends automatically, unless the
|
|
``only`` flag is set on a backend. This will be the first tried
|
|
backend outside the :obj:`set_backend` context manager.
|
|
|
|
Parameters
|
|
----------
|
|
backend : {object, 'scipy'}
|
|
The backend to use.
|
|
Can either be a ``str`` containing the name of a known backend
|
|
{'scipy'} or an object that implements the uarray protocol.
|
|
coerce : bool
|
|
Whether to coerce input types when trying this backend.
|
|
only : bool
|
|
If ``True``, no more backends will be tried if this fails.
|
|
Implied by ``coerce=True``.
|
|
try_last : bool
|
|
If ``True``, the global backend is tried after registered backends.
|
|
|
|
Raises
|
|
------
|
|
ValueError: If the backend does not implement ``numpy.scipy.fft``.
|
|
|
|
Notes
|
|
-----
|
|
This will overwrite the previously set global backend, which, by default, is
|
|
the SciPy implementation.
|
|
|
|
Examples
|
|
--------
|
|
We can set the global fft backend:
|
|
|
|
>>> from scipy.fft import fft, set_global_backend
|
|
>>> set_global_backend("scipy") # Sets global backend. "scipy" is the default backend.
|
|
>>> fft([1]) # Calls the global backend
|
|
array([1.+0.j])
|
|
"""
|
|
backend = _backend_from_arg(backend)
|
|
ua.set_global_backend(backend, coerce=coerce, only=only, try_last=try_last)
|
|
|
|
|
|
def register_backend(backend):
|
|
"""
|
|
Register a backend for permanent use.
|
|
|
|
Registered backends have the lowest priority and will be tried after the
|
|
global backend.
|
|
|
|
Parameters
|
|
----------
|
|
backend : {object, 'scipy'}
|
|
The backend to use.
|
|
Can either be a ``str`` containing the name of a known backend
|
|
{'scipy'} or an object that implements the uarray protocol.
|
|
|
|
Raises
|
|
------
|
|
ValueError: If the backend does not implement ``numpy.scipy.fft``.
|
|
|
|
Examples
|
|
--------
|
|
We can register a new fft backend:
|
|
|
|
>>> from scipy.fft import fft, register_backend, set_global_backend
|
|
>>> class NoopBackend: # Define an invalid Backend
|
|
... __ua_domain__ = "numpy.scipy.fft"
|
|
... def __ua_function__(self, func, args, kwargs):
|
|
... return NotImplemented
|
|
>>> set_global_backend(NoopBackend()) # Set the invalid backend as global
|
|
>>> register_backend("scipy") # Register a new backend
|
|
>>> fft([1]) # The registered backend is called because the global backend returns `NotImplemented`
|
|
array([1.+0.j])
|
|
>>> set_global_backend("scipy") # Restore global backend to default
|
|
|
|
"""
|
|
backend = _backend_from_arg(backend)
|
|
ua.register_backend(backend)
|
|
|
|
|
|
def set_backend(backend, coerce=False, only=False):
|
|
"""Context manager to set the backend within a fixed scope.
|
|
|
|
Upon entering the ``with`` statement, the given backend will be added to
|
|
the list of available backends with the highest priority. Upon exit, the
|
|
backend is reset to the state before entering the scope.
|
|
|
|
Parameters
|
|
----------
|
|
backend : {object, 'scipy'}
|
|
The backend to use.
|
|
Can either be a ``str`` containing the name of a known backend
|
|
{'scipy'} or an object that implements the uarray protocol.
|
|
coerce : bool, optional
|
|
Whether to allow expensive conversions for the ``x`` parameter. e.g.,
|
|
copying a NumPy array to the GPU for a CuPy backend. Implies ``only``.
|
|
only : bool, optional
|
|
If only is ``True`` and this backend returns ``NotImplemented``, then a
|
|
BackendNotImplemented error will be raised immediately. Ignoring any
|
|
lower priority backends.
|
|
|
|
Examples
|
|
--------
|
|
>>> import scipy.fft as fft
|
|
>>> with fft.set_backend('scipy', only=True):
|
|
... fft.fft([1]) # Always calls the scipy implementation
|
|
array([1.+0.j])
|
|
"""
|
|
backend = _backend_from_arg(backend)
|
|
return ua.set_backend(backend, coerce=coerce, only=only)
|
|
|
|
|
|
def skip_backend(backend):
|
|
"""Context manager to skip a backend within a fixed scope.
|
|
|
|
Within the context of a ``with`` statement, the given backend will not be
|
|
called. This covers backends registered both locally and globally. Upon
|
|
exit, the backend will again be considered.
|
|
|
|
Parameters
|
|
----------
|
|
backend : {object, 'scipy'}
|
|
The backend to skip.
|
|
Can either be a ``str`` containing the name of a known backend
|
|
{'scipy'} or an object that implements the uarray protocol.
|
|
|
|
Examples
|
|
--------
|
|
>>> import scipy.fft as fft
|
|
>>> fft.fft([1]) # Calls default SciPy backend
|
|
array([1.+0.j])
|
|
>>> with fft.skip_backend('scipy'): # We explicitly skip the SciPy backend
|
|
... fft.fft([1]) # leaving no implementation available
|
|
Traceback (most recent call last):
|
|
...
|
|
BackendNotImplementedError: No selected backends had an implementation ...
|
|
"""
|
|
backend = _backend_from_arg(backend)
|
|
return ua.skip_backend(backend)
|
|
|
|
|
|
set_global_backend('scipy', try_last=True)
|