# Copyright 2020-2021 Huawei Technologies Co., Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ============================================================================
"""Initializer for cell parameters."""
import numbers
import math
from functools import reduce
import numpy as np
from scipy.stats import truncnorm
from .seed import get_seed, _get_graph_seed
from . import dtype as mstype
from .tensor import Tensor
from .._c_expression import random_normal
_INITIALIZER_ALIAS = dict()
[docs]class Initializer:
"""
The abstract base class of the initializer.
Args:
kwargs (dict): Keyword arguments for Initializer.
"""
def __init__(self, **kwargs):
self._kwargs = kwargs
self._seed = None
@property
def seed(self):
if self._seed is None:
seed, seed2 = _get_graph_seed(get_seed(), "init")
else:
seed, seed2 = self._seed + 1, 0
return seed, seed2
@seed.setter
def seed(self, value):
self._seed = value
def _initialize(self, *kwargs):
raise NotImplementedError('Must be overridden!')
def __call__(self, arr):
return self._initialize(arr)
def _register(*aliases):
"""Return the alias register."""
def alias_reg(cls):
name = cls.__name__
name = name.lower()
if name not in _INITIALIZER_ALIAS:
_INITIALIZER_ALIAS[name] = cls
for alias in aliases:
if alias not in _INITIALIZER_ALIAS:
_INITIALIZER_ALIAS[alias] = cls
return cls
return alias_reg
def _assignment(arr, num):
"""Assign the value of `num` to `arr`."""
if arr.shape == ():
arr = arr.reshape(1)
arr[:] = num
arr = arr.reshape(())
else:
if isinstance(num, np.ndarray):
arr[:] = num[:]
else:
arr[:] = num
return arr
[docs]@_register('zeros')
class Zero(Initializer):
"""
Generates an array with constant value of zero in order to initialize a tensor.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer, Zero
>>> tensor1 = initializer(Zero(), [1, 2, 3], mindspore.float32)
>>> tensor2 = initializer('zeros', [1, 2, 3], mindspore.float32)
"""
def _initialize(self, arr):
_assignment(arr, 0)
[docs]@_register('ones')
class One(Initializer):
"""
Generates an array with constant value of one in order to initialize a tensor.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer, One
>>> tensor1 = initializer(One(), [1, 2, 3], mindspore.float32)
>>> tensor2 = initializer('ones', [1, 2, 3], mindspore.float32)
"""
def _initialize(self, arr):
_assignment(arr, 1)
def _calculate_fan_in_and_fan_out(shape):
"""
calculate fan_in and fan_out
Args:
shape (tuple): input shape.
Returns:
Tuple, a tuple with two elements, the first element is `n_in` and the second element is `n_out`.
"""
dimensions = len(shape)
if dimensions < 2:
raise ValueError("'fan_in' and 'fan_out' can not be computed for tensor with fewer than"
" 2 dimensions, but got dimensions {}.".format(dimensions))
if dimensions == 2: # Linear
fan_in = shape[1]
fan_out = shape[0]
else:
num_input_fmaps = shape[1]
num_output_fmaps = shape[0]
receptive_field_size = 1
for i in range(2, dimensions):
receptive_field_size *= shape[i]
fan_in = num_input_fmaps * receptive_field_size
fan_out = num_output_fmaps * receptive_field_size
return fan_in, fan_out
def _calculate_correct_fan(shape, mode):
"""
Calculate fan.
Args:
shape (tuple): input shape.
mode (str): only support fan_in and fan_out.
Returns:
fan_in or fan_out.
"""
mode = mode.lower()
valid_modes = ['fan_in', 'fan_out']
if mode not in valid_modes:
raise ValueError("'mode' {} not supported, please use one of {}".format(mode, valid_modes))
fan_in, fan_out = _calculate_fan_in_and_fan_out(shape)
return fan_in if mode == 'fan_in' else fan_out
def _calculate_gain(nonlinearity, param=None):
"""
Calculate gain.
Args:
nonlinearity (str): nonlinearity function.
param (str): used to calculate negative_slope.
Returns:
number.
"""
linear_fns = ['linear', 'conv1d', 'conv2d', 'conv3d', 'conv_transpose1d', 'conv_transpose2d', 'conv_transpose3d']
if nonlinearity in linear_fns or nonlinearity == 'sigmoid':
res = 1
elif nonlinearity == 'tanh':
res = 5.0 / 3
elif nonlinearity == 'relu':
res = math.sqrt(2.0)
elif nonlinearity == 'leaky_relu':
if param is None:
negative_slope = 0.01
elif not isinstance(param, bool) and isinstance(param, int) or isinstance(param, float):
# True/False are instances of int, hence check above
negative_slope = param
else:
raise ValueError("For 'HeUniform', 'negative_slope' {} is not a valid number."
"When 'nonlinearity' has been set to "
"'leaky_relu', 'negative_slope' should be int or float type, but got "
"{}.".format(param, type(param)))
res = math.sqrt(2.0 / (1 + negative_slope ** 2))
else:
raise ValueError("For 'HeUniform', the argument 'nonlinearity' should be one of "
"['sigmoid', 'tanh', 'relu' or 'leaky_relu'], "
"but got {}.".format(nonlinearity))
return res
def _calculate_in_and_out(arr):
"""
Calculate n_in and n_out.
Args:
arr (Array): Input array.
Returns:
Tuple, a tuple with two elements, the first element is `n_in` and the second element is `n_out`.
"""
dim = len(arr.shape)
if dim < 2:
raise ValueError("If initialize data with xavier uniform, the dimension of data must be greater than 1, "
"but got {}.".format(dim))
n_in = arr.shape[1]
n_out = arr.shape[0]
if dim > 2:
counter = reduce(lambda x, y: x * y, arr.shape[2:])
n_in *= counter
n_out *= counter
return n_in, n_out
[docs]@_register('he_normal')
class HeNormal(Initializer):
r"""
Generates an array with values sampled from HeKaiming Normal distribution
:math:`{N}(0, \text{sigma}^2)` in order to initialize a tensor, where
.. math::
sigma = \frac{gain} {\sqrt{fan\_mode}}
where :math:`gain` is an optional scaling factor. :math:`fan\_mode` is the number of input or output units of
the weight tensor, depending on the `mode` is 'fan_in' or 'fan_out'.
For details of HeUniform algorithm, please check `<https://arxiv.org/abs/1502.01852>`_.
Args:
negative_slope (int, float): The negative slope of the rectifier used after this layer
(only used when `nonlinearity` is 'leaky_relu'). Default: 0.
mode (str): Either 'fan_in' or 'fan_out'. Choosing 'fan_in' preserves the magnitude of the
variance of the weights in the forward pass. Choosing 'fan_out' preserves the magnitudes
in the backwards pass. Default: 'fan_in'.
nonlinearity (str): The non-linear function, recommended to use only with 'relu' or 'leaky_relu'.
Default: 'leaky_relu'.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer, HeNormal
>>> tensor1 = initializer(HeNormal(), [1, 2, 3], mindspore.float32)
>>> tensor2 = initializer('he_normal', [1, 2, 3], mindspore.float32)
"""
def __init__(self, negative_slope=0, mode='fan_in', nonlinearity='leaky_relu'):
super(HeNormal, self).__init__(negative_slope=negative_slope, mode=mode, nonlinearity=nonlinearity)
self.negative_slope = negative_slope
self.mode = mode
self.nonlinearity = nonlinearity
def _initialize(self, arr):
fan = _calculate_correct_fan(arr.shape, self.mode)
gain = _calculate_gain(self.nonlinearity, self.negative_slope)
std = gain / math.sqrt(fan)
data = np.random.normal(0, std, arr.shape)
_assignment(arr, data)
[docs]class Constant(Initializer):
"""
Generates an array with constant value in order to initialize a tensor.
Args:
value (Union[int, numpy.ndarray]): The value to initialize.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer
>>> tensor1 = initializer(0, [1, 2, 3], mindspore.float32)
>>> tensor2 = initializer(5, [1, 2, 3], mindspore.float32)
"""
def __init__(self, value):
super(Constant, self).__init__(value=value)
self.value = value
def _initialize(self, arr):
_assignment(arr, self.value)
[docs]@_register()
class Identity(Initializer):
"""
Generates a 2 dimension identity matrix array in order to initialize a tensor.
Raises:
ValueError: If the dimension of input tensor is not equal to 2.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer, Identity
>>> tensor1 = initializer(Identity(), [2, 3], mindspore.float32)
>>> tensor2 = initializer('identity', [2, 3], mindspore.float32)
"""
def _initialize(self, arr):
if len(arr.shape) != 2:
raise ValueError('For Identity initializer, the dimension of the initialized tensor should be 2, '
'but got {}.'.format(len(arr.shape)))
value = np.eye(arr.shape[0], arr.shape[1])
_assignment(arr, value)
[docs]@_register()
class Sparse(Initializer):
"""
Generates a 2 dimension sparse matrix array in order to initialize a tensor. The non-zero positions
will be filled with the value sampled from the normal distribution :math:`{N}(0, 0.01)`
Args:
sparsity (float): The fraction of elements being set to zero in each column.
sigma (float): The standard deviation of the normal distribution. Default: 0.01.
Raises:
ValueError: If the dimension of input tensor is not equal to 2.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer, Sparse
>>> tensor1 = initializer(Sparse(sparsity=0.1, sigma=0.01), [5, 8], mindspore.float32)
"""
def __init__(self, sparsity, sigma=0.01):
super(Sparse, self).__init__()
self.sparsity = sparsity
self.sigma = sigma
def _initialize(self, arr):
if len(arr.shape) != 2:
raise ValueError('For Sparse initializer, the dimension of the initialized tensor should be 2, '
'but got {}.'.format(len(arr.shape)))
rows, cols = arr.shape
zero_num = int(np.ceil(self.sparsity * rows))
data = np.random.normal(0, self.sigma, arr.shape)
for col_idx in range(cols):
row_idx = np.random.permutation(list(range(rows)))[: zero_num]
data[row_idx, col_idx] = 0.
_assignment(arr, data)
[docs]@_register()
class Dirac(Initializer):
"""
Generates an array with the Dirac delta function in order to initialize a tensor.
It tries to preserves the identity of input for convolution layers.
For group convolution, each group of channels will be preserved respectively.
Args:
groups (int): The number of group in convolution layer. Default: 1.
Raises:
ValueError: If the dimension of the initialized tensor is not in [3, 4, 5].
ValueError: The first dimension of the initialized tensor cannot be divisible by group.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer, Dirac
>>> tensor1 = initializer(Dirac(groups=2), [6, 4, 3, 3], mindspore.float32)
>>> tensor2 = initializer("dirac", [6, 4, 3, 3], mindspore.float32)
"""
def __init__(self, groups=1):
super(Dirac, self).__init__()
self.groups = groups
def _initialize(self, arr):
dimension = len(arr.shape)
data = np.zeros(arr.shape)
if dimension not in [3, 4, 5]:
raise ValueError("For Dirac initializer, only support "
"to initialize tensor with dimension of 3, 4 or 5, but got {}.".format(dimension))
shapes = arr.shape
if shapes[0] % self.groups != 0:
raise ValueError("For Dirac initializer, the first dimension of"
"the initialized tensor must be divisible by groups, "
"but got first dimension{}, groups{}.".format(shapes[0], self.groups))
out_channel_per_group = shapes[0] // self.groups
min_dim = min(out_channel_per_group, shapes[1])
for group in range(self.groups):
for dim in range(min_dim):
if dimension == 3:
data[group * out_channel_per_group + dim, dim, shapes[2]//2] = 1
elif dimension == 4:
data[group * out_channel_per_group + dim, dim, shapes[2] // 2, shapes[3] // 2] = 1
else:
data[group * out_channel_per_group + dim, dim, shapes[2] // 2, shapes[3] // 2, shapes[4] // 2] = 1
_assignment(arr, data)
[docs]@_register()
class Orthogonal(Initializer):
r"""
Generates a (semi) orthogonal matrix array in order to initialize a tensor.
The dimension of input tensor must have at least 2 dimensions.
If the dimension is greater than 2, the trailing dimensions will be flattened.
Args:
gain (float): An optional scaling factor. Default: 1.
Raises:
ValueError: If the dimension of input tensor is less than 2.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer, Orthogonal
>>> tensor1 = initializer(Orthogonal(gain=2.), [2, 3, 4], mindspore.float32)
>>> tensor2 = initializer('orthogonal', [2, 3, 4], mindspore.float32)
"""
def __init__(self, gain=1.):
super(Orthogonal, self).__init__(gain=gain)
self.gain = gain
def _initialize(self, arr):
if len(arr.shape) < 2:
raise ValueError('For Orthogonal initializer, the dimension of the initialized tensor should'
' be no less than 2, but got {}.'.format(len(arr.shape)))
rows = arr.shape[0]
cols = np.prod(arr.shape) // rows
data = np.random.normal(0, 1, size=(rows, cols))
if rows < cols:
data = data.T
q, r = np.linalg.qr(data)
d = np.diag(r)
ph = np.sign(d)
q *= ph
if rows < cols:
q = q.T
q = q * self.gain
_assignment(arr, q.reshape(arr.shape))
[docs]@_register()
class VarianceScaling(Initializer):
r"""
Generates an random array with scaling in order to initialize a tensor.
When `distribution` is 'truncated_normal' or 'untruncated_normal', the value will be sampled from truncated or
untruncated normal distribution with a mean of 0 and a scaled standard deviation
:math:`stddev = \sqrt{\frac{scale}{n}}`. :math:`n` will be the number of input units if `mode` is 'fan_in',
the number of output units if `mode` is 'fan_out', the average of 'fan_in' and 'fan_out' if `mode` is 'fan_avg'.
When `distribution` is 'uniform', the value will be sampled from a uniform distribution within the limit of
:math:`[-\sqrt{\frac{3*scale}{n}}, \sqrt{\frac{3*scale}{n}}]`.
Args:
scale (float): The scaling factor. Default: 1.0.
mode (str): Should be 'fan_in', 'fan_out' or 'fan_avg'. Default: 'fan_in'.
distribution(str): The type of distribution chose to sample values. It should be
'uniform', 'truncated_normal' or 'untruncated_normal'. Default: 'truncated_normal'.
Raises:
ValueError: If `scale` is not greater than 0.
ValueError: If `mode` is not 'fan_in', 'fan_out' or 'fan_avg'.
ValueError: If `distribution` is not 'uniform', 'truncated_normal' or 'untruncated_normal'.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer, VarianceScaling
>>> tensor1 = initializer(VarianceScaling(scale=1.0, mode='fan_out',
... distribution='untruncated_normal'), [2, 3], mindspore.float32)
>>> tensor2 = initializer('varianceScaling', [2, 3], mindspore.float32)
"""
def __init__(self, scale=1.0, mode='fan_in', distribution='truncated_normal'):
super(VarianceScaling, self).__init__(scale=scale, mode=mode, distribution=distribution)
if scale <= 0.:
raise ValueError("For VarianceScaling initializer, "
"the argument 'scale' must be greater than 0, but got {}.".format(scale))
if mode not in ['fan_in', 'fan_out', 'fan_avg']:
raise ValueError("For VarianceScaling initializer, the argument 'mode' must be fan_in, "
"fan_out or fan_avg, but got {}.".format(mode))
if distribution not in ['uniform', 'truncated_normal', 'untruncated_normal']:
raise ValueError("For VarianceScaling initializer, the argument 'distribution' must be uniform, "
"truncated_norm or untruncated_norm, but got {}.".format(distribution))
self.scale = scale
self.mode = mode
self.distribution = distribution
def _initialize(self, arr):
scale = self.scale
fan_in, fan_out = _calculate_fan_in_and_fan_out(arr.shape)
if self.mode == 'fan_in':
scale /= max(1., fan_in)
elif self.mode == 'fan_out':
scale /= max(1., fan_out)
else:
scale /= max(1., (fan_in + fan_out) / 2.)
if self.distribution == 'truncated_norm':
stddev = np.sqrt(scale) / 0.87962566103423978
data = truncnorm.rvs(-2, 2, loc=0, scale=stddev, size=arr.shape, random_state=None)
elif self.distribution == 'untruncated_normal':
stddev = np.sqrt(scale)
data = np.random.normal(0, stddev, arr.shape)
else:
limit = np.sqrt(3.0 * scale)
data = np.random.uniform(-limit, limit, arr.shape)
_assignment(arr, data)
[docs]@_register()
class Normal(Initializer):
r"""
Generates an array with values sampled from Normal distribution :math:`{N}(\text{sigma}, \text{mean})` in order to
initialize a tensor.
.. math::
f(x) = \frac{1} {\sqrt{2*π} * sigma}exp(-\frac{(x - mean)^2} {2*{sigma}^2})
Args:
sigma (float): The standard deviation of Normal distribution. Default: 0.01.
mean (float): The mean of Normal distribution. Default: 0.0.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer, Normal
>>> tensor1 = initializer(Normal(), [1, 2, 3], mindspore.float32)
>>> tensor2 = initializer('normal', [1, 2, 3], mindspore.float32)
"""
def __init__(self, sigma=0.01, mean=0.0):
super(Normal, self).__init__(sigma=sigma, mean=mean)
self.sigma = sigma
self.mean = mean
def _initialize(self, arr):
seed, seed2 = self.seed
output_tensor = Tensor(np.zeros(arr.shape, dtype=np.float32))
random_normal(arr.shape, seed, seed2, output_tensor)
output_data = output_tensor.asnumpy()
output_data = output_data * self.sigma + self.mean
_assignment(arr, output_data)
[docs]@_register()
class TruncatedNormal(Initializer):
r"""
Generates an array with values sampled from Truncated Normal distribution in order to initialize a tensor.
Args:
sigma (float): The standard deviation of Truncated Normal distribution. Default: 0.01.
Examples:
>>> import mindspore
>>> from mindspore.common.initializer import initializer, TruncatedNormal
>>> tensor1 = initializer(TruncatedNormal(), [1, 2, 3], mindspore.float32)
>>> tensor2 = initializer('truncatedNormal', [1, 2, 3], mindspore.float32)
"""
def __init__(self, sigma=0.01):
super(TruncatedNormal, self).__init__(sigma=sigma)
self.sigma = sigma
def _initialize(self, arr):
tmp = truncnorm.rvs(-2, 2, loc=0, scale=self.sigma, size=arr.shape, random_state=None)
_assignment(arr, tmp)
[docs]def initializer(init, shape=None, dtype=mstype.float32):
"""
Create and initialize a tensor.
Args:
init (Union[Tensor, str, Initializer, numbers.Number]): Initialize value.
- `str`: The `init` should be the alias of the class inheriting from `Initializer` and the corresponding
class will be called in practice. The value of 'init' can be "normal", "ones" or "zeros", etc.
- `Initializer`: The `init` should be the class inheriting from `Initializer` to initialize tensor.
- `numbers.Number`: The `Constant` will be called to initialize tensor.
shape (Union[tuple, list, int]): The shape of the initialized tensor. Default: None.
dtype (:class:`mindspore.dtype`): The type of data in initialized tensor. Default: mindspore.float32.
Returns:
Tensor, return is Tensor object.
Raises:
TypeError: The type of the argument 'init' is not correct.
ValueError: The shape of the tensor which is passed through 'init' is not the same as that passed by 'shape'.
Examples:
>>> import numpy as np
>>> import mindspore
>>> from mindspore import Tensor
>>> from mindspore.common.initializer import initializer, One
>>> data = Tensor(np.zeros([1, 2, 3]), mindspore.float32)
>>> tensor1 = initializer(data, [1, 2, 3], mindspore.float32)
>>> tensor2 = initializer('ones', [1, 2, 3], mindspore.float32)
>>> tensor3 = initializer(One(), [1, 2, 3], mindspore.float32)
>>> tensor4 = initializer(0, [1, 2, 3], mindspore.float32)
"""
if not isinstance(init, (Tensor, numbers.Number, str, Initializer)):
raise TypeError("For 'initializer', the type of the 'init' argument should be 'Tensor', 'number', 'string' "
"or 'initializer', but got {}.".format(type(init)))
if isinstance(init, Tensor):
init_shape = init.shape
shape = shape if isinstance(shape, (tuple, list)) else [shape]
if shape is not None and init_shape != tuple(shape):
raise ValueError("For 'initializer', the shape of the 'init' argument should be same as "
"the argument 'shape', but got the "
"'init' shape {} and the 'shape' {}.".format(list(init.shape), shape))
return init
if isinstance(shape, list):
shape = tuple(shape)
elif isinstance(shape, numbers.Number):
shape = (shape,)
for value in shape if shape is not None else ():
if not isinstance(value, int) or value <= 0:
raise ValueError(f"For 'initializer', the argument 'shape' is invalid, the value of 'shape' "
f"must be positive integer, "
f"but got {shape}")
if isinstance(init, str):
init = _INITIALIZER_ALIAS[init.lower()]()
if init is None:
raise ValueError("The class corresponding to '{}' was not found.".format(init))
elif isinstance(init, numbers.Number):
init = Constant(init)
shape = shape if shape is not None else init.shape
init_obj = Tensor(dtype=dtype, shape=shape, init=init)
return init_obj
__all__ = [
'Initializer',
'initializer',
'TruncatedNormal',
'Normal',
'Uniform',
'HeUniform',
'HeNormal',
'XavierUniform',
'One',
'Zero',
'Constant',
'Identity',
'Sparse',
'Dirac',
'Orthogonal',
'VarianceScaling']