# tf.keras.losses.BinaryCrossentropy

Computes the cross-entropy loss between true labels and predicted labels.

``````tf.keras.losses.BinaryCrossentropy(
from_logits=False, label_smoothing=0, reduction=losses_utils.ReductionV2.AUTO,
name='binary_crossentropy'
)
``````

### Used in the notebooks

Used in the guide Used in the tutorials

Use this cross-entropy loss when there are only two label classes (assumed to be 0 and 1). For each example, there should be a single floating-point value per prediction.

In the snippet below, each of the four examples has only a single floating-pointing value, and both `y_pred` and `y_true` have the shape `[batch_size]`.

#### Usage:

``````bce = tf.keras.losses.BinaryCrossentropy()
loss = bce([0., 0., 1., 1.], [1., 1., 1., 0.])
print('Loss: ', loss.numpy())  # Loss: 11.522857
``````

Usage with the `tf.keras` API:

``````model = tf.keras.Model(inputs, outputs)
model.compile('sgd', loss=tf.keras.losses.BinaryCrossentropy())
``````

#### Args:

• `from_logits`: Whether to interpret `y_pred` as a tensor of logit values. By default, we assume that `y_pred` contains probabilities (i.e., values in [0, 1]). Note: Using from_logits=True may be more numerically stable.
• `label_smoothing`: Float in [0, 1]. When 0, no smoothing occurs. When > 0, we compute the loss between the predicted labels and a smoothed version of the true labels, where the smoothing squeezes the labels towards 0.5. Larger values of `label_smoothing` correspond to heavier smoothing.
• `reduction`: (Optional) Type of `tf.keras.losses.Reduction` to apply to loss. Default value is `AUTO`. `AUTO` indicates that the reduction option will be determined by the usage context. For almost all cases this defaults to `SUM_OVER_BATCH_SIZE`. When used with `tf.distribute.Strategy`, outside of built-in training loops such as `tf.keras` `compile` and `fit`, using `AUTO` or `SUM_OVER_BATCH_SIZE` will raise an error. Please see https://www.tensorflow.org/alpha/tutorials/distribute/training_loops for more details on this.
• `name`: (Optional) Name for the op.

## Methods

### `__call__`

View source

``````__call__(
y_true, y_pred, sample_weight=None
)
``````

Invokes the `Loss` instance.

#### Args:

• `y_true`: Ground truth values. shape = `[batch_size, d0, .. dN]`
• `y_pred`: The predicted values. shape = `[batch_size, d0, .. dN]`
• `sample_weight`: Optional `sample_weight` acts as a coefficient for the loss. If a scalar is provided, then the loss is simply scaled by the given value. If `sample_weight` is a tensor of size `[batch_size]`, then the total loss for each sample of the batch is rescaled by the corresponding element in the `sample_weight` vector. If the shape of `sample_weight` is `[batch_size, d0, .. dN-1]` (or can be broadcasted to this shape), then each loss element of `y_pred` is scaled by the corresponding value of `sample_weight`. (Note on`dN-1`: all loss functions reduce by 1 dimension, usually axis=-1.)

#### Returns:

Weighted loss float `Tensor`. If `reduction` is `NONE`, this has shape `[batch_size, d0, .. dN-1]`; otherwise, it is scalar. (Note `dN-1` because all loss functions reduce by 1 dimension, usually axis=-1.)

#### Raises:

• `ValueError`: If the shape of `sample_weight` is invalid.

### `from_config`

View source

``````@classmethod
from_config(
config
)
``````

Instantiates a `Loss` from its config (output of `get_config()`).

#### Args:

• `config`: Output of `get_config()`.

#### Returns:

A `Loss` instance.

### `get_config`

View source

``````get_config()
``````