qfeval_functions.functions.nancumprod

nancumprod(x, dim)[source]

Compute the cumulative product along a dimension, treating NaN as 1.

This function calculates the cumulative product of elements along the specified dimension, where NaN values are treated as 1 (multiplicative identity) for the purpose of computing the cumulative product. However, positions with NaN values in the original tensor remain NaN in the output.

Parameters:

x (Tensor) – The input tensor containing values.
dim (int) – The dimension along which to compute the cumulative product.

Returns:

A tensor of the same shape as the input, containing the cumulative product values. Original NaN positions remain NaN.

Return type:

Tensor

Example

>>> # Simple cumulative product with NaN
>>> x = torch.tensor([2.0, nan, 3.0, 4.0])
>>> QF.nancumprod(x, dim=0)
tensor([ 2., nan,  6., 24.])

>>> # 2D tensor along columns
>>> x = torch.tensor([[1.0, 2.0, nan, 4.0],
...                   [2.0, nan, 3.0, 5.0]])
>>> QF.nancumprod(x, dim=1)
tensor([[ 1.,  2., nan,  8.],
        [ 2., nan,  6., 30.]])

>>> # Cumulative product along rows
>>> x = torch.tensor([[2.0, 3.0],
...                   [nan, 4.0],
...                   [5.0, 2.0]])
>>> QF.nancumprod(x, dim=0)
tensor([[ 2.,  3.],
        [nan, 12.],
        [10., 24.]])

>>> # Multiple NaNs
>>> x = torch.tensor([1.0, nan, nan, 2.0, 3.0])
>>> QF.nancumprod(x, dim=0)
tensor([1., nan, nan, 2., 6.])