from torch import topk


class GreedyDecoder:
    def __call__(self, outputs):
        """Greedy Decoder. Returns highest probability of class labels for each timestep

        Args:
            outputs (torch.Tensor): shape (input length, batch size, number of classes (including blank))

        Returns:
            torch.Tensor: class labels per time step.
        """
        _, indices = topk(outputs, k=1, dim=-1)
        return indices[..., 0]