chainer.functions.sum¶

chainer.functions.sum(x, axis=None, keepdims=False)[source]¶

Sum of array elements over a given axis.

Parameters

x (Variable or N-dimensional array) – Elements to sum. A $(s_1, s_2, ..., s_N)$ -shaped float array.
axis (None, int, or tuple of int) – Axis along which a sum is performed. The default (axis = None) is perform a sum over all the dimensions of the input array.
keepdims (bool) – If True, the specified axes are remained as axes of length one.

Returns

Output variable.

Return type

Variable

Example

>>> x = np.arange(6).reshape(2,3).astype(np.float32)
>>> x
array([[0., 1., 2.],
       [3., 4., 5.]], dtype=float32)
>>> y = F.sum(x)
>>> y.shape
()
>>> y.array
array(15., dtype=float32)
>>> y = F.sum(x, axis=1)
>>> y.shape
(2,)
>>> y.array
array([ 3., 12.], dtype=float32)
>>> y = F.sum(x, keepdims=True)
>>> y.shape
(1, 1)
>>> y.array
array([[15.]], dtype=float32)