mindspore.nn.LossBase
- class mindspore.nn.LossBase(reduction='mean')[source]
Base class for other losses.
Other losses derived from this should implement their own construct and use method self.get_loss to apply reduction to loss values.
- Parameters
reduction (str) – Type of reduction to be applied to loss. The optional values are “mean”, “sum”, and “none”. Default: “mean”.
- Raises
ValueError – If reduction is not one of ‘none’, ‘mean’, ‘sum’.
- Supported Platforms:
Ascend
GPU
CPU
- get_axis(x)[source]
Get a range of axis for input.
- Parameters
x (Tensor) – Tensor of any shape.
Examples
>>> class Net(nn.LossBase): ... def __init__(self, reduction='mean'): ... super(Net, self).__init__(reduction) ... self.abs = ops.Abs() ... ... def construct(self, logits, labels): ... x = self.abs(logits - labels) ... axis = self.get_axis(x) ... return axis >>> net = Net() >>> # Case 1: logits.shape = labels.shape = (3,) >>> logits = Tensor(np.array([1, 2, 3]), mindspore.float32) >>> labels = Tensor(np.array([1, 2, 3]), mindspore.float32) >>> output = net(logits, labels) >>> print(output) (0,) >>> # Case 2: logits.shape = labels.shape = (3, 3) >>> logits = Tensor(np.array([[1, 2, 3],[1, 2, 3],[1, 2, 3]]), mindspore.float32) >>> labels = Tensor(np.array([[1, 2, 3],[1, 2, 3],[1, 2, 3]]), mindspore.float32) >>> output = net(logits, labels) >>> print(output) (0, 1)
- get_loss(x, weights=1.0)[source]
Computes the weighted loss.
- Parameters
x (Tensor) – Tensor of shape \((N, *)\) where \(*\) means, any number of additional dimensions.
weights (Union[float, Tensor]) – Optional Tensor whose rank is either 0, or the same rank as inputs, and must be broadcastable to inputs (i.e., all dimensions must be either 1, or the same as the corresponding inputs dimension). Default: 1.0.
- Returns
Return the weighted loss.
Examples
>>> class Net(nn.LossBase): ... def __init__(self, reduction='mean'): ... super(Net, self).__init__(reduction) ... self.abs = ops.Abs() ... ... def construct(self, logits, labels): ... x = self.abs(logits - labels) ... output = self.get_loss(x) ... return output >>> net = Net() >>> # Case 1: logits.shape = labels.shape = (3,) >>> logits = Tensor(np.array([1, 2, 3]), mindspore.float32) >>> labels = Tensor(np.array([1, 2, 2]), mindspore.float32) >>> output = net(logits, labels) >>> print(output) 0.33333334 >>> # Case 2: logits.shape = labels.shape = (3, 3) >>> logits = Tensor(np.array([[1, 2, 3],[1, 2, 3],[1, 2, 3]]), mindspore.float32) >>> labels = Tensor(np.array([[1, 2, 2],[1, 2, 3],[1, 2, 3]]), mindspore.float32) >>> output = net(logits, labels) >>> print(output) 0.11111111