def iterspace(features, sortem=False):
"""
Returns a generator that yields each of the points defined by the
discrete space 'features'. The 'rightmost' feature is iterated
most rapidly. There is no requirement that the items in a feature
be mutually unique.
If optional 'sortem' is True, the items in each feature will be
sorted before the space is enumerated.
>>> features = (('b', 'a'), (1, 2, 1), ('p', 'n'))
>>> tuple(iterspace(features))
(('b', 1, 'p'), ('b', 1, 'n'), ('b', 2, 'p'), ('b', 2, 'n'), ('b', 1, 'p'), ('b', 1, 'n'), ('a', 1, 'p'), ('a', 1, 'n'), ('a', 2, 'p'), ('a', 2, 'n'), ('a', 1, 'p'), ('a', 1, 'n'))
>>> tuple(iterspace(((3, 1, 2), ('z', 'a')), True))
((1, 'a'), (1, 'z'), (2, 'a'), (2, 'z'), (3, 'a'), (3, 'z'))
"""
# sorted or as is; use frozentuple to verify immutability of feature values
collect = sorted if sortem else tuple
features = tuple(frozentuple(collect(feature)) for feature in features)
ndim = len(features)
# bootstrap the combinatoric work with the iterator's next for the first dimension
iterstack = [iter(features[0]).next]
valstack = [None]
while True:
try:
# advance the last element; can raise StopIteration or IndexError
valstack[-1] = iterstack[-1]()
# fill out remaining dimensions of the iterators and the values
while len(iterstack) < ndim:
feature_iter = iter(features[len(iterstack)]).next
iterstack.append(feature_iter)
valstack.append(feature_iter())
yield tuple(valstack)
except StopIteration:
# drop back so lower dimension gets advanced
iterstack.pop()
valstack.pop()
except IndexError:
return
def iterspace(features, sortem=False):
"""
Returns a generator that yields each of the points defined by the
discrete space 'features'. The 'rightmost' feature is iterated
most rapidly. There is no requirement that the items in a feature
be mutually unique.
If optional 'sortem' is True, the items in each feature will be
sorted before the space is enumerated.
>>> features = (('b', 'a'), (1, 2, 1), ('p', 'n'))
>>> tuple(iterspace(features))
(('b', 1, 'p'), ('b', 1, 'n'), ('b', 2, 'p'), ('b', 2, 'n'), ('b', 1, 'p'), ('b', 1, 'n'), ('a', 1, 'p'), ('a', 1, 'n'), ('a', 2, 'p'), ('a', 2, 'n'), ('a', 1, 'p'), ('a', 1, 'n'))
>>> tuple(iterspace(((3, 1, 2), ('z', 'a')), True))
((1, 'a'), (1, 'z'), (2, 'a'), (2, 'z'), (3, 'a'), (3, 'z'))
"""
# sorted or as is; use frozentuple to verify immutability of feature values
collect = sorted if sortem else tuple
features = tuple(frozentuple(collect(feature)) for feature in features)
ndim = len(features)
# bootstrap the combinatoric work with the iterator's next for the first dimension
iterstack = [iter(features[0]).next]
valstack = [None]
while True:
try:
# advance the last element; can raise StopIteration or IndexError
valstack[-1] = iterstack[-1]()
# fill out remaining dimensions of the iterators and the values
while len(iterstack) < ndim:
feature_iter = iter(features[len(iterstack)]).next
iterstack.append(feature_iter)
valstack.append(feature_iter())
yield tuple(valstack)
except StopIteration:
# drop back so lower dimension gets advanced
iterstack.pop()
valstack.pop()
except IndexError:
return
def __call__(self, length, shift, norm=None):
key = length, shift, norm
windows = self.windows
hamming = windows.get(key)
if hamming is None:
# check preconditions etc
if int(length) != length or length < 0:
raise ValueError("expected non-negative integral length, got %s" % (length,))
length = int(length)
if int(shift) != shift or shift < 0:
raise ValueError("expected non-negative integral shift, got %s" % (shift,))
shift = int(shift)
if not (norm is None or norm == 'sum' or norm == 'sumsq' or norm == 'mode'):
raise ValueError("expected norm of None or 'sum' or 'mode', got %s" % (repr(norm),))
key = frozentuple(key)
if length == 0:
hamming = frozentuple()
elif length == 1:
hamming = frozentuple([float(1 << shift)])
else:
# create unscaled Hamming window values
bottom = self.BOTTOM
cos_offset = self.COS_OFFSET
cos_scale = self.COS_SCALE
length1 = length - 1
twopireciplength1 = 2 * PI / length1
hamming = [None] * length
left, right = 0, length1
numbottom = 0
while left <= right:
val = cos_offset - cos_scale * cos(twopireciplength1 * left)
assert bottom <= val <= 1
if val == bottom:
numbottom += 1
hamming[left] = hamming[right] = val
left += 1
right -= 1
assert numbottom > 0
assert (hamming[length1 // 2] == 1
or (length % 2 == 0 and hamming[(length1-1) // 2] == hamming[length1 // 2]))
# scale and truncate
# note: we truncate rather than round; for the
# positive data in the window this errs on the side of
# slightly less energy than if we rounded, but it avoids
# the problem of rounding making the sum be more than
# 1 for clients using the 'sum'-to-one normalization
if norm is None:
norm_sum = 1
elif norm == 'mode':
norm_sum = hamming[length1 // 2]
assert norm_sum == hamming[length // 2]
elif norm == 'sum':
norm_sum = sum(hamming)
elif norm == 'sumsq':
norm_sum = sqrt(sum(h*h for h in hamming))
else:
assert False, "unreachable"
assert norm_sum > 0
norm_scale = float(1 << shift) / norm_sum
hamming = windows[key] = frozentuple(int(h * norm_scale) for h in hamming)
assert type(hamming) is frozentuple
return hamming
def __call__(self, length, shift, norm=None):
key = length, shift, norm
windows = self.windows
hamming = windows.get(key)
if hamming is None:
# check preconditions etc
if int(length) != length or length < 0:
raise ValueError(
"expected non-negative integral length, got %s" %
(length, ))
length = int(length)
if int(shift) != shift or shift < 0:
raise ValueError(
"expected non-negative integral shift, got %s" % (shift, ))
shift = int(shift)
if not (norm is None or norm == 'sum' or norm == 'sumsq'
or norm == 'mode'):
raise ValueError(
"expected norm of None or 'sum' or 'mode', got %s" %
(repr(norm), ))
key = frozentuple(key)
if length == 0:
hamming = frozentuple()
elif length == 1:
hamming = frozentuple([float(1 << shift)])
else:
# create unscaled Hamming window values
bottom = self.BOTTOM
cos_offset = self.COS_OFFSET
cos_scale = self.COS_SCALE
length1 = length - 1
twopireciplength1 = 2 * PI / length1
hamming = [None] * length
left, right = 0, length1
numbottom = 0
while left <= right:
val = cos_offset - cos_scale * cos(
twopireciplength1 * left)
assert bottom <= val <= 1
if val == bottom:
numbottom += 1
hamming[left] = hamming[right] = val
left += 1
right -= 1
assert numbottom > 0
assert (hamming[length1 // 2] == 1
or (length % 2 == 0 and hamming[(length1 - 1) // 2]
== hamming[length1 // 2]))
# scale and truncate
# note: we truncate rather than round; for the
# positive data in the window this errs on the side of
# slightly less energy than if we rounded, but it avoids
# the problem of rounding making the sum be more than
# 1 for clients using the 'sum'-to-one normalization
if norm is None:
norm_sum = 1
elif norm == 'mode':
norm_sum = hamming[length1 // 2]
assert norm_sum == hamming[length // 2]
elif norm == 'sum':
norm_sum = sum(hamming)
elif norm == 'sumsq':
norm_sum = sqrt(sum(h * h for h in hamming))
else:
assert False, "unreachable"
assert norm_sum > 0
norm_scale = float(1 << shift) / norm_sum
hamming = windows[key] = frozentuple(
int(h * norm_scale) for h in hamming)
assert type(hamming) is frozentuple
return hamming
