def n_pars_by_partition(partition):
n = 0
for _, shape in dictlist.leafs(partition):
shape = (shape,) if isinstance(shape, int) else shape
n += np.prod(shape)
return int(n)
def array_partition_views(array, partition):
"""Return a dictlist with different items corresponding to different sub
views into an array.
This function can be used to use different parts of a one-dimensional
array as a collection of arrays with differing without the need to
reallocate. E.g the first half of an array might correspond to a matrix,
the next entry to a scalar and the rest to a vector.
The function takes two arguments. The first, ``array`` is supposed to
resemble the flat array, while the second is a dictlist partitioning the
array into views of given shapes.
Here, the leaves of ``partition`` will be treated as shapes, of which a
view into ``array`` should be contained in the result with the same path.
Parameters
----------
array : np.array or gp.garray
numpy or gnumpy array of ndim 1.
partition : dictlist
Dictlist -- that is a a dictionary containing either lists or dicts as
its elements, except leave nodes. These should be either tuples or ints
to represent shapes of arays.
Examples
--------
>>> from breze.arch.util import array_partition_views
>>> partition = {'first': (2,),
... 'second': (2, 3),}
>>> flat = np.arange(8)
>>> views = array_partition_views(flat, partition)
>>> views['first']
... # doctest: +NORMALIZE_WHITESPACE
array([0, 1])
>>> views['second']
... # doctest: +NORMALIZE_WHITESPACE
array([[2, 3, 4],
[5, 6, 7]])
"""
views = dictlist.copy(partition)
pathsshapes = sorted(list(dictlist.leafs(partition)))
n_used = 0
for path, shape in pathsshapes:
item = dictlist.get(partition, path)
shape = (item,) if isinstance(item, (int, long)) else item
size = int(np.prod(shape))
dictlist.set_(views, path, array[n_used:n_used + size].reshape(shape))
n_used += size
return views
def test_dictlist_dfs():
tree = make_dictlist()
contents = sorted(list(dictlist.leafs(tree)))
assert contents[0] == (('bla',), 2)
assert contents[1] == (('blo', 0), (2, 3))
assert contents[2] == (('blo', 1), 5)
assert contents[3] == (('blu', 'far', 0), 1)
assert contents[4] == (('blu', 'far', 1), 2)
assert contents[5] == (('blu', 'foo'), (2, 4))
assert contents[6] == (('blubb',), (2, 3))
def array_partition_views(array, partition):
views = dictlist.copy(partition)
pathsshapes = sorted(list(dictlist.leafs(partition)))
n_used = 0
for path, shape in pathsshapes:
item = dictlist.get(partition, path)
shape = (item,) if isinstance(item, (int, long)) else item
size = int(np.prod(shape))
dictlist.set_(views, path, array[n_used:n_used + size].reshape(shape))
n_used += size
return views
