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mZ G dd deZdS )    )AnyListUnionN)Tensortensor)_mer_compute_mer_update)Metricc                       s   e Zd ZU dZdZeed< dZeed< dZeed< e	ed< e	ed< de
f fd	d
Zdeeee f deeee f ddfddZde	fddZ  ZS )MatchErrorRatea  Match Error Rate (`MER`_) is a common metric of the performance of an automatic speech recognition system.

    This value indicates the percentage of words that were incorrectly predicted and inserted.
    The lower the value, the better the performance of the ASR system with a MatchErrorRate of 0 being a perfect score.
    Match error rate can then be computed as:

    .. math::
        mer = \frac{S + D + I}{N + I} = \frac{S + D + I}{S + D + C + I}

    where:
        - :math:`S` is the number of substitutions,
        - :math:`D` is the number of deletions,
        - :math:`I` is the number of insertions,
        - :math:`C` is the number of correct words,
        - :math:`N` is the number of words in the reference (:math:`N=S+D+C`).

    As input to ``forward`` and ``update`` the metric accepts the following input:

    - ``preds`` (:class:`~List`): Transcription(s) to score as a string or list of strings
    - ``target`` (:class:`~List`): Reference(s) for each speech input as a string or list of strings

    As output of ``forward`` and ``compute`` the metric returns the following output:

    - ``mer`` (:class:`~torch.Tensor`): A tensor with the match error rate

    Args:
        kwargs: Additional keyword arguments, see :ref:`Metric kwargs` for more info.

    Examples:
        >>> preds = ["this is the prediction", "there is an other sample"]
        >>> target = ["this is the reference", "there is another one"]
        >>> mer = MatchErrorRate()
        >>> mer(preds, target)
        tensor(0.4444)
    Fis_differentiablehigher_is_betterfull_state_updateerrortotalkwargsc                    sJ   t  jdi | | jdtdtjddd | jdtdtjddd d S )Nerrorsr   )dtypesum)dist_reduce_fxr    )super__init__	add_stater   torchfloat)selfr   	__class__r   I/home/ubuntu/.local/lib/python3.10/site-packages/torchmetrics/text/mer.pyr   C   s   zMatchErrorRate.__init__predstargetreturnNc                 C   s.   t ||\}}|  j|7  _|  j|7  _dS )z*Update state with predictions and targets.N)r   r   r   )r   r   r    r   r   r   r   r   updateK   s   zMatchErrorRate.updatec                 C   s   t | j| jS )zCalculate the Match error rate.)r   r   r   )r   r   r   r   computeX   s   zMatchErrorRate.compute)__name__
__module____qualname____doc__r   bool__annotations__r   r   r   r   r   r   strr   r"   r#   __classcell__r   r   r   r   r
      s$   
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   )typingr   r   r   r   r   r    torchmetrics.functional.text.merr   r   torchmetrics.metricr	   r
   r   r   r   r   <module>   s   