nnf_ctc_loss function

Ctc_loss

The Connectionist Temporal Classification loss.

nnf_ctc_loss(
  log_probs,
  targets,
  input_lengths,
  target_lengths,
  blank = 0,
  reduction = c("mean", "sum", "none"),
  zero_infinity = FALSE
)

Arguments

• log_probs: $(T, N, C)$ where C = number of characters in alphabet including blank, T = input length, and N = batch size. The logarithmized probabilities of the outputs (e.g. obtained with nnf_log_softmax ).
• targets: $(N, S)$ or (sum(target_lengths)). Targets cannot be blank. In the second form, the targets are assumed to be concatenated.
• input_lengths: $(N)$. Lengths of the inputs (must each be $\leq T$)
• target_lengths: $(N)$. Lengths of the targets
• blank: (int, optional) Blank label. Default $0$.
• reduction: (string, optional) – Specifies the reduction to apply to the output: 'none' | 'mean' | 'sum'. 'none': no reduction will be applied, 'mean': the sum of the output will be divided by the number of elements in the output, 'sum': the output will be summed. Default: 'mean'
• zero_infinity: (bool, optional) Whether to zero infinite losses and the associated gradients. Default: FALSE Infinite losses mainly occur when the inputs are too short to be aligned to the targets.