分类目录:《深入浅出TensorFlow2函数》总目录
相关文章:
· 深入浅出TensorFlow2函数——tf.reduce_sum
· 深入浅出TensorFlow2函数——tf.math.reduce_sum
· 深入浅出Pytorch函数——torch.sum
· 深入浅出PaddlePaddle函数——paddle.sum
计算张量各维度上元素的总和。文章来源:https://www.toymoban.com/news/detail-499898.html
语法
tf.reduce_sum(
input_tensor, axis=None, keepdims=False, name=None
)
参数
-
input_tensor
:[Tensor
] 待求和的多维Tensor
。 -
axis
:求和运算的维度。如果为None
,则计算所有元素的和并返回包含单个元素的Tensor
变量,否则必须在 [ − rank ( x ) , rank ( x ) ] [-\text{rank}(x), \text{rank}(x)] [−rank(x),rank(x)]范围内。如果 axis [ i ] < 0 \text{axis}[i]<0 axis[i]<0,则维度将变为 rank + axis [ i ] \text{rank} + \text{axis}[i] rank+axis[i],默认值为None
。 -
keepdim
:[bool
] 是否在输出Tensor
中保留减小的维度。如keepdim=True
,否则结果张量的维度将比输入张量小,默认值为False
。 -
name
:[可选,str
] 操作的名称,默认值为None
。
返回值
与input_tensor
具有相同dtype
的求和后的tensor
。文章来源地址https://www.toymoban.com/news/detail-499898.html
实例
>>> # x has a shape of (2, 3) (two rows and three columns):
>>> x = tf.constant([[1, 1, 1], [1, 1, 1]])
>>> x.numpy()
array([[1, 1, 1],
[1, 1, 1]], dtype=int32)
>>> # sum all the elements
>>> # 1 + 1 + 1 + 1 + 1+ 1 = 6
>>> tf.reduce_sum(x).numpy()
6
>>> # reduce along the first dimension
>>> # the result is [1, 1, 1] + [1, 1, 1] = [2, 2, 2]
>>> tf.reduce_sum(x, 0).numpy()
array([2, 2, 2], dtype=int32)
>>> # reduce along the second dimension
>>> # the result is [1, 1] + [1, 1] + [1, 1] = [3, 3]
>>> tf.reduce_sum(x, 1).numpy()
array([3, 3], dtype=int32)
>>> # keep the original dimensions
>>> tf.reduce_sum(x, 1, keepdims=True).numpy()
array([[3],
[3]], dtype=int32)
>>> # reduce along both dimensions
>>> # the result is 1 + 1 + 1 + 1 + 1 + 1 = 6
>>> # or, equivalently, reduce along rows, then reduce the resultant array
>>> # [1, 1, 1] + [1, 1, 1] = [2, 2, 2]
>>> # 2 + 2 + 2 = 6
>>> tf.reduce_sum(x, [0, 1]).numpy()
6
函数实现
@tf_export("math.reduce_sum", "reduce_sum", v1=[])
@dispatch.add_dispatch_support
def reduce_sum(input_tensor, axis=None, keepdims=False, name=None):
"""Computes the sum of elements across dimensions of a tensor.
This is the reduction operation for the elementwise `tf.math.add` op.
Reduces `input_tensor` along the dimensions given in `axis`.
Unless `keepdims` is true, the rank of the tensor is reduced by 1 for each
of the entries in `axis`, which must be unique. If `keepdims` is true, the
reduced dimensions are retained with length 1.
If `axis` is None, all dimensions are reduced, and a
tensor with a single element is returned.
For example:
>>> # x has a shape of (2, 3) (two rows and three columns):
>>> x = tf.constant([[1, 1, 1], [1, 1, 1]])
>>> x.numpy()
array([[1, 1, 1],
[1, 1, 1]], dtype=int32)
>>> # sum all the elements
>>> # 1 + 1 + 1 + 1 + 1+ 1 = 6
>>> tf.reduce_sum(x).numpy()
6
>>> # reduce along the first dimension
>>> # the result is [1, 1, 1] + [1, 1, 1] = [2, 2, 2]
>>> tf.reduce_sum(x, 0).numpy()
array([2, 2, 2], dtype=int32)
>>> # reduce along the second dimension
>>> # the result is [1, 1] + [1, 1] + [1, 1] = [3, 3]
>>> tf.reduce_sum(x, 1).numpy()
array([3, 3], dtype=int32)
>>> # keep the original dimensions
>>> tf.reduce_sum(x, 1, keepdims=True).numpy()
array([[3],
[3]], dtype=int32)
>>> # reduce along both dimensions
>>> # the result is 1 + 1 + 1 + 1 + 1 + 1 = 6
>>> # or, equivalently, reduce along rows, then reduce the resultant array
>>> # [1, 1, 1] + [1, 1, 1] = [2, 2, 2]
>>> # 2 + 2 + 2 = 6
>>> tf.reduce_sum(x, [0, 1]).numpy()
6
Args:
input_tensor: The tensor to reduce. Should have numeric type.
axis: The dimensions to reduce. If `None` (the default), reduces all
dimensions. Must be in the range `[-rank(input_tensor),
rank(input_tensor)]`.
keepdims: If true, retains reduced dimensions with length 1.
name: A name for the operation (optional).
Returns:
The reduced tensor, of the same dtype as the input_tensor.
@compatibility(numpy)
Equivalent to np.sum apart the fact that numpy upcast uint8 and int32 to
int64 while tensorflow returns the same dtype as the input.
@end_compatibility
"""
return reduce_sum_with_dims(input_tensor, axis, keepdims, name,
_ReductionDims(input_tensor, axis))
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