/usr/lib/python2.7/dist-packages/dipy/reconst/cache.py is in python-dipy 0.10.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 | from dipy.core.onetime import auto_attr
class Cache(object):
"""Cache values based on a key object (such as a sphere or gradient table).
Notes
-----
This class is meant to be used as a mix-in::
class MyModel(Model, Cache):
pass
class MyModelFit(Fit):
pass
Inside a method on the fit, typical usage would be::
def odf(sphere):
M = self.model.cache_get('odf_basis_matrix', key=sphere)
if M is None:
M = self._compute_basis_matrix(sphere)
self.model.cache_set('odf_basis_matrix', key=sphere, value=M)
"""
# We use this method instead of __init__ to construct the cache, so
# that the class can be used as a mixin, without having to worry about
# calling the super-class constructor
@auto_attr
def _cache(self):
return {}
def cache_set(self, tag, key, value):
"""Store a value in the cache.
Parameters
----------
tag : str
Description of the cached value.
key : object
Key object used to look up the cached value.
value : object
Value stored in the cache for each unique combination
of ``(tag, key)``.
Examples
--------
>>> def compute_expensive_matrix(parameters):
... # Imagine the following computation is very expensive
... return (p**2 for p in parameters)
>>> c = Cache()
>>> parameters = (1, 2, 3)
>>> X1 = compute_expensive_matrix(parameters)
>>> c.cache_set('expensive_matrix', parameters, X1)
>>> X2 = c.cache_get('expensive_matrix', parameters)
>>> X1 is X2
True
"""
self._cache[(tag, key)] = value
def cache_get(self, tag, key, default=None):
"""Retrieve a value from the cache.
Parameters
----------
tag : str
Description of the cached value.
key : object
Key object used to look up the cached value.
default : object
Value to be returned if no cached entry is found.
Returns
-------
v : object
Value from the cache associated with ``(tag, key)``. Returns
`default` if no cached entry is found.
"""
return self._cache.get((tag, key), default)
def cache_clear(self):
"""Clear the cache.
"""
self._cache = {}
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