/TensorFlow 1.15

# tf.compat.v2.sparse.reduce_sum

Computes the sum of elements across dimensions of a SparseTensor.

This Op takes a SparseTensor and is the sparse counterpart to `tf.reduce_sum()`. In particular, this Op also returns a dense `Tensor` if `output_is_sparse` is `False`, or a `SparseTensor` if `output_is_sparse` is `True`.

Note: if `output_is_sparse` is True, a gradient is not defined for this function, so it can't be used in training models that need gradient descent.

Reduces `sp_input` along the dimensions given in `axis`. Unless `keepdims` is true, the rank of the tensor is reduced by 1 for each entry in `axis`. If `keepdims` is true, the reduced dimensions are retained with length 1.

If `axis` has no entries, all dimensions are reduced, and a tensor with a single element is returned. Additionally, the axes can be negative, similar to the indexing rules in Python.

#### For example:

```# 'x' represents [[1, ?, 1]
#                 [?, 1, ?]]
# where ? is implicitly-zero.
tf.sparse.reduce_sum(x) ==> 3
tf.sparse.reduce_sum(x, 0) ==> [1, 1, 1]
tf.sparse.reduce_sum(x, 1) ==> [2, 1]  # Can also use -1 as the axis.
tf.sparse.reduce_sum(x, 1, keepdims=True) ==> [, ]
tf.sparse.reduce_sum(x, [0, 1]) ==> 3
```
Args
`sp_input` The SparseTensor to reduce. Should have numeric type.
`axis` The dimensions to reduce; list or scalar. If `None` (the default), reduces all dimensions.
`keepdims` If true, retain reduced dimensions with length 1.
`output_is_sparse` If true, returns a `SparseTensor` instead of a dense `Tensor` (the default).
`name` A name for the operation (optional).
Returns
The reduced Tensor or the reduced SparseTensor if `output_is_sparse` is True.