/
constant.py
99 lines (67 loc) · 2.46 KB
/
constant.py
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import numpy
from chainer.backends import cuda
from chainer import initializer
class Identity(initializer.Initializer):
"""Initializes array with the identity matrix.
It initializes the given array with the constant
multiple of the identity matrix.
Note that arrays to be passed must be 2D squared matrices.
Attributes:
scale (scalar): A constant to be multiplied to identity matrices.
"""
def __init__(self, scale=1.0, dtype=None):
self.scale = scale
super(Identity, self).__init__(dtype)
def __call__(self, array):
if self.dtype is not None:
assert array.dtype == self.dtype
shape = array.shape
if len(shape) != 2 or shape[0] != shape[1]:
raise ValueError('Identity matrix initialization can only be used '
'for 2D squared matrices.')
array[...] = 0
xp = cuda.get_array_module(array)
xp.fill_diagonal(array, self.scale)
class _Constant(initializer.Initializer):
fill_value = None
def __init__(self, dtype=None):
if not (isinstance(self.fill_value, (numpy.ndarray, cuda.ndarray)) or
numpy.isscalar(self.fill_value)):
raise ValueError(
'fill_value must be either scalar, numpy.ndarray or '
'cupy.ndarray.')
super(_Constant, self).__init__(dtype)
def __call__(self, array):
if self.dtype is not None:
assert array.dtype == self.dtype
xp = cuda.get_array_module(array)
array[...] = xp.asarray(self.fill_value)
class Constant(_Constant):
"""Initializes array with constant value.
Attributes:
~Constant.fill_value (scalar or numpy.ndarray or cupy.ndarray):
A constant to be assigned to the initialized array.
Broadcast is allowed on this assignment.
dtype: Data type specifier.
"""
def __init__(self, fill_value, dtype=None):
self.fill_value = fill_value
super(Constant, self).__init__(dtype)
class Zero(_Constant):
"""Initializes array to all-zero.
Attributes:
~Zero.dtype: Data type specifier.
"""
fill_value = 0.0
class One(_Constant):
"""Initializes array to all-one.
Attributes:
~One.dtype: Data type specifier.
"""
fill_value = 1.0
class NaN(_Constant):
"""Initializes array to all-NaN.
Attributes:
~NaN.dtype: Data type specifier.
"""
fill_value = numpy.nan