TensorDictBase.prod#

Returns the product of every leaf, over all its elements or along a batch dimension.

Parameters:

dim (int or str, optional) – the batch dimension to reduce. A negative dim counts from the end of the batch dimensions. "feature" reduces the feature dimensions of each leaf instead, and the result keeps the batch size. A tuple reduces only its first dimension; passing one is deprecated and will be removed in TensorDict 0.17. Defaults to None, which reduces every element of each leaf, and the result has an empty batch size.
keepdim (bool, optional) – if True, the reduced batch dimensions are kept with size 1. Not allowed with dim="feature". Defaults to False.

Keyword Arguments:

dtype (dtype, optional) – if given, each leaf is cast to this dtype before the reduction, which helps to prevent overflows. Defaults to None.
reduce (bool, optional) – if True, reduces all the leaves together and returns a single tensor. Without dim, the result is a scalar. With an int dim, the leaves are concatenated along dim first, so they must have the same number of dimensions. With dim="feature", the result has the batch size as its shape. With feature dimensions, a negative dim counts from the end of each leaf. Starting with TensorDict 0.17, the default will change to counting it from the end of the batch dimensions, as with reduce=False. Defaults to False.

Returns:

A new tensordict, or a tensor if reduce=True.

Examples

>>> import torch
>>> from tensordict import TensorDict
>>> td = TensorDict(a=torch.tensor([[1.0, 2.0], [3.0, 4.0]]), batch_size=[2])
>>> td.prod()["a"]
tensor(24.)
>>> td.prod(dim=0)["a"]
tensor([3., 8.])
>>> td.prod(dim="feature")["a"]
tensor([ 2., 12.])
>>> td.prod(reduce=True)
tensor(24.)

Every tensordict class and every tensorclass has this method. For the other methods, see Methods by task.

TensorDictBase.prod#

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