bernoulli.py 文件源码

def _log_prob(self, event):
    # TODO(jaana): The current sigmoid_cross_entropy_with_logits has
    # inconsistent  behavior for logits = inf/-inf.
    event = math_ops.cast(event, self.logits.dtype)
    logits = self.logits
    # sigmoid_cross_entropy_with_logits doesn't broadcast shape,
    # so we do this here.

    broadcast = lambda logits, event: (
        array_ops.ones_like(event) * logits,
        array_ops.ones_like(logits) * event)

    # First check static shape.
    if (event.get_shape().is_fully_defined() and
        logits.get_shape().is_fully_defined()):
      if event.get_shape() != logits.get_shape():
        logits, event = broadcast(logits, event)
    else:
      logits, event = control_flow_ops.cond(
          distribution_util.same_dynamic_shape(logits, event),
          lambda: (logits, event),
          lambda: broadcast(logits, event))
    return -nn.sigmoid_cross_entropy_with_logits(labels=event, logits=logits)