mindspore.mutable

mindspore.mutable(input_data, dynamic_len=False)

Make a constant value mutable.

Currently, all the inputs of Cell except Tensor such as scalar, tuple, list and dict, are regarded as constant values. The constant values are non-differentiable and used to do constant folding in the optimization process.

Besides, currently when the network input is tuple[Tensor], list[Tensor] or dict[Tensor], even without changing the shape and dtype of the Tensors, the network will be re-compiled when calling this network repeatedly because the these inputs are regarded as constant values.

To solve the above problems, we provide api mutable to make the constant inputs of Cell ‘mutable’. A ‘mutable’ input means that it is changed to be a variable input just like Tensor and the most important thing is that it will be differentiable.

When the input_data is tuple or list and dynamic_len is False, mutable will return a constant length tuple or list with all mutable elements. If dynamic_len is True, the length of the return tuple or list will be dynamic.

If a dynamic length tuple or list is used as the input of the network and the network is repeatedly called, and the length of the tuple or list is different for each run, it does not need to be re-compiled.

Parameters

• input_data (Union[Tensor, scalar, tuple, list, dict]) – The input data to be made mutable. If ‘input_data’ is list/tuple/dict, the type of each element should also in the valid types.

• dynamic_len (bool) – Whether to set the whole sequence to be dynamic length. In graph compilation, if dynamic_len is True , the input_data must be list or tuple and the elements of input_data must have the same type and shape. Default: False .

Warning

This is an experimental API that is subject to change or deletion. dynamic_len is an experimental argument. Currently, dynamic_len is not supported to be True .

Note

Currently this api only works in GRAPH mode.

Returns

The origin input data which has been set mutable.

Raises

• TypeError – If input_data is not one of Tensor, scalar, tuple, list, dict or their nested structure.

• TypeError – If dynamic_len is True and input_data is not tuple or list.

• ValueError – If dynamic_len is True , input_data is tuple or list but the elements within input_data do not have the same type.

Supported Platforms:

Ascend GPU CPU

Examples

>>> from mindspore import mutable, nn, ops, Tensor, context
>>> from mindspore import dtype as mstype
>>> context.set_context(mode=context.GRAPH_MODE)
>>> class Net(nn.Cell):
...     def __init__(self):
...         super(Net, self).__init__()
...         self.matmul = ops.MatMul()
...
...     def construct(self, z):
...         x = z[0]
...         y = z[1]
...         out = self.matmul(x, y)
...         return out
...
>>> class GradNetWrtX(nn.Cell):
...     def __init__(self, net):
...         super(GradNetWrtX, self).__init__()
...         self.net = net
...         self.grad_op = ops.GradOperation()
...
...     def construct(self, z):
...         gradient_function = self.grad_op(self.net)
...         return gradient_function(z)
...
>>> z = mutable((Tensor([[0.5, 0.6, 0.4], [1.2, 1.3, 1.1]], dtype=mstype.float32),
...              Tensor([[0.01, 0.3, 1.1], [0.1, 0.2, 1.3], [2.1, 1.2, 3.3]], dtype=mstype.float32)))
>>> output = GradNetWrtX(Net())(z)
>>> print(output)
(Tensor(shape=[2, 3], dtype=Float32, value=
[[ 1.41000009e+00,  1.60000002e+00,  6.59999943e+00],
 [ 1.41000009e+00,  1.60000002e+00,  6.59999943e+00]]), Tensor(shape=[3, 3], dtype=Float32, value=
[[ 1.70000005e+00,  1.70000005e+00,  1.70000005e+00],
 [ 1.89999998e+00,  1.89999998e+00,  1.89999998e+00],
 [ 1.50000000e+00,  1.50000000e+00,  1.50000000e+00]]))