reduce_sum

paddle.fluid.layers.nn. reduce_sum ( input, dim=None, keep_dim=False, name=None ) [source]

Computes the sum of tensor elements over the given dimension.

Parameters

  • input (Variable) – The input variable which is a Tensor, the data type is float32, float64, int32, int64.

  • dim (list|int, optional) – The dimensions along which the sum is performed. If None, sum all elements of input and return a Tensor variable with a single element, otherwise must be in the range \([-rank(input), rank(input))\). If \(dim[i] < 0\), the dimension to reduce is \(rank + dim[i]\).

  • keep_dim (bool, optional) – Whether to reserve the reduced dimension in the output Tensor. The result tensor will have one fewer dimension than the input unless keep_dim is true, default value is False.

  • name (str, optional) – The default value is None. Normally there is no need for user to set this property. For more information, please refer to Name

Returns

Tensor, results of summation operation on the specified dim of input tensor, it’s data type is the same as input’s Tensor.

Return type

Variable

Raises

TypeError, if out data type is different with the input data type. –

Examples

import paddle.fluid as fluid
import paddle
paddle.enable_static()
# x is a Tensor variable with following elements:
#    [[0.2, 0.3, 0.5, 0.9]
#     [0.1, 0.2, 0.6, 0.7]]
# Each example is followed by the corresponding output tensor.
x = fluid.data(name='x', shape=[2, 4], dtype='float32')
fluid.layers.reduce_sum(x)  # [3.5]
fluid.layers.reduce_sum(x, dim=0)  # [0.3, 0.5, 1.1, 1.6]
fluid.layers.reduce_sum(x, dim=-1)  # [1.9, 1.6]
fluid.layers.reduce_sum(x, dim=1, keep_dim=True)  # [[1.9], [1.6]]

# y is a Tensor variable with shape [2, 2, 2] and elements as below:
#      [[[1, 2], [3, 4]],
#      [[5, 6], [7, 8]]]
# Each example is followed by the corresponding output tensor.
y = fluid.data(name='y', shape=[2, 2, 2], dtype='float32')
fluid.layers.reduce_sum(y, dim=[1, 2]) # [10, 26]
fluid.layers.reduce_sum(y, dim=[0, 1]) # [16, 20]