def sin_cos_positional_embedding(x,
num_encoding_functions,
include_input=True,
log_sampling=True):
"""Given coordinate positions of sampling points as a (N,3) array, this functions returns embeds each point with the sine and cosine function
Args:
x (nn.Variable or nn.NdArray): Shape is (N, 3).
num_encoding_functions (int): number of frequencies to encode for each grid position
include_input (bool, optional): Whether include the original grid position along with the encoding of the position. Defaults to True.
log_sampling (bool, optional): Sample logarithmically and not linearly. Defaults to True.
Returns:
[nn.Variable or nn.NdArray]: (N, num_encoding_functions*3*2+3) if include_input is True else (N, num_encoding_functions*3*2)
"""
encoding = [x] if include_input else []
if log_sampling:
frequency_increments = F.arange(0, num_encoding_functions)
frequency_bands = F.pow2(
F.constant(2, shape=frequency_increments.shape),
frequency_increments)
else:
frequency_bands = F.arange(2**0,
2**(num_encoding_functions - 1) + 1e-5,
(2**(num_encoding_functions - 1) - 1) /
(num_encoding_functions - 1.0))
for freq in frequency_bands:
for func in [F.sin, F.cos]:
encoding.append(func(x * F.reshape(freq, (1, 1))))
return F.concatenate(*encoding, axis=x.ndim - 1)
def __rpow__(self, other):
"""
Element-wise power function.
Part of the implementation of the power operator expression.
Args:
other (float or ~nnabla.Variable): Internally calling
:func:`~nnabla.functions.pow2` or
:func:`~nnabla.functions.r_pow_scalar` according to the
type.
Returns: :class:`nnabla.Variable`
"""
import nnabla.functions as F
if isinstance(other, Variable):
return F.pow2(other, self)
return F.r_pow_scalar(self, other)
def __pow__(self, other):
"""
Element-wise power function.
Implements the power operator expression ``A ** B``, together with :func:`~nnabla.variable.__rpow__` .
When a scalar is specified for ``other``, this function performs an
element-wise operation for all elements in ``self``.
Args:
other (float or ~nnabla.Variable): Internally calling
:func:`~nnabla.functions.pow2` or
:func:`~nnabla.functions.pow_scalar` according to the
type.
Returns: :class:`nnabla.Variable`
"""
import nnabla.functions as F
if isinstance(other, Variable):
return F.pow2(self, other)
return F.pow_scalar(self, other)