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Paddle/python/paddle/tensor/stat.py

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# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
#
# 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.
# TODO: define statistical functions of a tensor
from ..fluid.layers import reduce_mean #DEFINE_ALIAS
__all__ = ['mean', 'reduce_mean', 'std', 'var', 'numel']
import numpy as np
from ..fluid.framework import Variable
from ..fluid.layer_helper import LayerHelper
from ..fluid.framework import core, in_dygraph_mode
from ..fluid import layers
from .search import where
from ..fluid.data_feeder import convert_dtype, check_variable_and_dtype, check_type, check_dtype
import paddle
def mean(x, axis=None, keepdim=False, name=None):
"""
Computes the mean of the input tensor's elements along ``axis``.
Args:
x (Tensor): The input Tensor with data type float32, float64.
axis (int|list|tuple, optional): The axis along which to perform mean
calculations. ``axis`` should be int, list(int) or tuple(int). If
``axis`` is a list/tuple of dimension(s), mean is calculated along
all element(s) of ``axis`` . ``axis`` or element(s) of ``axis``
should be in range [-D, D), where D is the dimensions of ``x`` . If
``axis`` or element(s) of ``axis`` is less than 0, it works the
same way as :math:`axis + D` . If ``axis`` is None, mean is
calculated over all elements of ``x``. Default is None.
keepdim (bool, optional): Whether to reserve the reduced dimension(s)
in the output Tensor. If ``keepdim`` is True, the dimensions of
the output Tensor is the same as ``x`` except in the reduced
dimensions(it is of size 1 in this case). Otherwise, the shape of
the output Tensor is squeezed in ``axis`` . Default is False.
name (str, optional): Name for the operation (optional, default is None).
For more information, please refer to :ref:`api_guide_Name`.
Returns:
Tensor, results of average along ``axis`` of ``x``, with the same data
type as ``x``.
Examples:
.. code-block:: python
import paddle
import numpy as np
paddle.disable_static()
x = np.array([[[1, 2, 3, 4],
[5, 6, 7, 8],
[9, 10, 11, 12]],
[[13, 14, 15, 16],
[17, 18, 19, 20],
[21, 22, 23, 24]]], 'float32')
x = paddle.to_tensor(x)
out1 = paddle.mean(x)
# [12.5]
out2 = paddle.mean(x, axis=-1)
# [[ 2.5 6.5 10.5]
# [14.5 18.5 22.5]]
out3 = paddle.mean(x, axis=-1, keepdim=True)
# [[[ 2.5]
# [ 6.5]
# [10.5]]
# [[14.5]
# [18.5]
# [22.5]]]
out4 = paddle.mean(x, axis=[0, 2])
# [ 8.5 12.5 16.5]
"""
if isinstance(axis, int):
axis = [axis]
reduce_all = True if axis is None \
or len(axis)==0 \
or len(axis) == len(x.shape) else False
if axis is None or len(axis) == 0:
axis = [0]
if in_dygraph_mode():
return core.ops.reduce_mean(x, 'dim', axis, 'keep_dim', keepdim,
'reduce_all', reduce_all)
check_variable_and_dtype(x, 'x/input', ['float32', 'float64'],
'mean/reduce_mean')
check_type(axis, 'axis/dim', (int, list, tuple), 'mean/reduce_mean')
if isinstance(axis, (list, tuple)):
for item in axis:
check_type(item, 'elements of axis/dim', (int), 'mean/reduce_mean')
helper = LayerHelper('mean', **locals())
attrs = {'dim': axis, 'keep_dim': keepdim, 'reduce_all': reduce_all}
out = helper.create_variable_for_type_inference(x.dtype)
helper.append_op(
type='reduce_mean', inputs={'X': x}, outputs={'Out': out}, attrs=attrs)
return out
def var(x, axis=None, unbiased=True, keepdim=False, name=None):
"""
Computes the variance of ``x`` along ``axis`` .
Args:
x (Tensor): The input Tensor with data type float32, float64.
axis (int|list|tuple, optional): The axis along which to perform
variance calculations. ``axis`` should be int, list(int) or
tuple(int). If ``axis`` is a list/tuple of dimension(s), variance
is calculated along all element(s) of ``axis`` . ``axis`` or
element(s) of ``axis`` should be in range [-D, D), where D is the
dimensions of ``x`` . If ``axis`` or element(s) of ``axis`` is less
than 0, it works the same way as :math:`axis + D` . If ``axis`` is
None, variance is calculated over all elements of ``x``. Default
is None.
unbiased (bool, optional): Whether to use the unbiased estimation. If
``unbiased`` is True, the divisor used in the computation is
:math:`N - 1`, where :math:`N` represents the number of elements
along ``axis`` , otherwise the divisor is :math:`N`. Default is True.
keepdim (bool, optional): Whether to reserve the reduced dimension(s)
in the output Tensor. If ``keepdim`` is True, the dimensions of
the output Tensor is the same as ``x`` except in the reduced
dimensions(it is of size 1 in this case). Otherwise, the shape of
the output Tensor is squeezed in ``axis`` . Default is False.
name (str, optional): Name for the operation (optional, default is None).
For more information, please refer to :ref:`api_guide_Name`.
Returns:
Tensor, results of variance along ``axis`` of ``x``, with the same data
type as ``x``.
Examples:
.. code-block:: python
import paddle
import numpy as np
paddle.disable_static()
x = np.array([[1.0, 2.0, 3.0], [1.0, 4.0, 5.0]])
x = paddle.to_tensor(x)
out1 = paddle.var(x)
# [2.66666667]
out2 = paddle.var(x, axis=1)
# [1. 4.33333333]
"""
if not in_dygraph_mode():
check_variable_and_dtype(x, 'x', ['float32', 'float64'], 'var')
u = mean(x, axis, True, name)
out = paddle.sum((x - u)**2, axis, keepdim=keepdim, name=name)
n = paddle.cast(paddle.numel(x), x.dtype) \
/ paddle.cast(paddle.numel(out), x.dtype)
if unbiased:
one_const = paddle.ones([1], x.dtype)
n = where(n > one_const, n - 1., one_const)
out /= n
return out
def std(x, axis=None, unbiased=True, keepdim=False, name=None):
"""
Computes the standard-deviation of ``x`` along ``axis`` .
Args:
x (Tensor): The input Tensor with data type float32, float64.
axis (int|list|tuple, optional): The axis along which to perform
standard-deviation calculations. ``axis`` should be int, list(int)
or tuple(int). If ``axis`` is a list/tuple of dimension(s),
standard-deviation is calculated along all element(s) of ``axis`` .
``axis`` or element(s) of ``axis`` should be in range [-D, D),
where D is the dimensions of ``x`` . If ``axis`` or element(s) of
``axis`` is less than 0, it works the same way as :math:`axis + D` .
If ``axis`` is None, standard-deviation is calculated over all
elements of ``x``. Default is None.
unbiased (bool, optional): Whether to use the unbiased estimation. If
``unbiased`` is True, the standard-deviation is calculated via the
unbiased estimator. If ``unbiased`` is True, the divisor used in
the computation is :math:`N - 1`, where :math:`N` represents the
number of elements along ``axis`` , otherwise the divisor is
:math:`N`. Default is True.
keepdim (bool, optional): Whether to reserve the reduced dimension(s)
in the output Tensor. If ``keepdim`` is True, the dimensions of
the output Tensor is the same as ``x`` except in the reduced
dimensions(it is of size 1 in this case). Otherwise, the shape of
the output Tensor is squeezed in ``axis`` . Default is False.
name (str, optional): Name for the operation (optional, default is None).
For more information, please refer to :ref:`api_guide_Name`.
Returns:
Tensor, results of standard-deviation along ``axis`` of ``x``, with the
same data type as ``x``.
Examples:
.. code-block:: python
import paddle
import numpy as np
paddle.disable_static()
x = np.array([[1.0, 2.0, 3.0], [1.0, 4.0, 5.0]])
x = paddle.to_tensor(x)
out1 = paddle.std(x)
# [1.63299316]
out2 = paddle.std(x, axis=1)
# [1. 2.081666]
"""
if not in_dygraph_mode():
check_variable_and_dtype(x, 'x', ['float32', 'float64'], 'std')
out = var(**locals())
return paddle.sqrt(out)
def numel(x, name=None):
"""
Returns the number of elements for a tensor, which is a int64 Tensor with shape [1] in static mode
or a scalar value in imperative mode
Args:
x (Tensor): The input Tensor, it's data type can be bool, float16, float32, float64, int32, int64.
Returns:
Tensor: The number of elements for the input Tensor.
Raises:
TypeError: ``x`` must be a Tensor and the data type of ``x`` must be one of bool, float16, float32, float64, int32, int64.
Examples:
.. code-block:: python
import paddle
paddle.disable_static()
x = paddle.full(shape=[4, 5, 7], fill_value=0, dtype='int32')
numel = paddle.numel(x) # 140
"""
if in_dygraph_mode():
return core.ops.size(x)
if not isinstance(x, Variable):
raise TypeError("x must be a Tensor in numel")
helper = LayerHelper('numel', **locals())
out = helper.create_variable_for_type_inference(
dtype=core.VarDesc.VarType.INT64)
helper.append_op(type='size', inputs={'Input': x}, outputs={'Out': out})
return out