# Copyright 2020 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 mindspore import log as logger
from . import dtype as mstype
from .tensor import Tensor
_INITIALIZER_ALIAS = dict()
[docs]class Initializer:
"""
The base class of the initializer.
Args:
kwargs (dict): Keyword arguments for Initializer.
Returns:
Array, assigned array.
"""
def __init__(self, **kwargs):
self._kwargs = kwargs
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):
"""
Initialize the array to zero.
Args:
arr (Array): The array to be assigned.
Returns:
Array, assigned array.
"""
def _initialize(self, arr):
_assignment(arr, 0)
[docs]@_register('ones')
class One(Initializer):
"""
Initialize the array to one.
Args:
arr (Array): The array to be assigned.
Returns:
Array, assigned array.
"""
def _initialize(self, arr):
_assignment(arr, 1)
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 greater than 1.")
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
class _Constant(Initializer):
"""
Initialize a constant.
Args:
value (int or numpy.ndarray): The value to initialize.
Returns:
Array, initialize array.
"""
def __init__(self, value):
super(_Constant, self).__init__(value=value)
self.value = value
def _initialize(self, arr):
_assignment(arr, self.value)
[docs]@_register()
class Normal(Initializer):
"""
Initialize a normal array, and obtain values N(0, sigma) from the uniform distribution
to fill the input tensor.
Args:
sigma (float): The sigma of the array. Default: 0.01.
Returns:
Array, normal array.
"""
def __init__(self, sigma=0.01):
super(Normal, self).__init__(sigma=sigma)
self.sigma = sigma
def _initialize(self, arr):
tmp = np.random.normal(0, self.sigma, arr.shape)
_assignment(arr, tmp)
[docs]@_register()
class TruncatedNormal(Initializer):
"""
Initialize a truncated normal distribution which is a bounded normal distribution within N(low, high).
Args:
sigma (float): The sigma of the array. Default: 0.01.
Returns:
Array, truncated normal array.
"""
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.
shape (Union[tuple, list, int]): A list of integers, a tuple of integers or an integer as the shape of
output. Default: None.
dtype (:class:`mindspore.dtype`): The type of data in initialized tensor. Default: mstype.float32.
Returns:
Tensor, initialized tensor.
Examples:
>>> tensor = initializer('ones', [1, 2, 3], mstype.float32)
"""
if not isinstance(init, (Tensor, numbers.Number, str, Initializer)):
raise TypeError('Unsupported init type.')
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("The shape of init should be same as variable shape, but got the shape of init {} and "
"the variable shape {}.".format(list(init.shape()), shape))
return init
try:
arr = np.ndarray(shape)
except ValueError:
msg = "Error shape={}".format(shape)
logger.error(msg)
raise ValueError(msg)
if isinstance(init, numbers.Number):
init_obj = _Constant(init)
elif isinstance(init, str):
init_obj = _INITIALIZER_ALIAS[init.lower()]()
else:
init_obj = init
init_obj(arr)
return Tensor(arr, dtype=dtype)
__all__ = [
'Initializer',
'initializer',
'TruncatedNormal',
'Normal',
'Uniform',
'HeUniform',
'XavierUniform',
'One',
'Zero']