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from_logits=False, reduction="auto", name="sparse_categorical_crossentropy" |
) |
Computes the crossentropy loss between the labels and predictions. |
Use this crossentropy loss function when there are two or more label classes. We expect labels to be provided as integers. If you want to provide labels using one-hot representation, please use CategoricalCrossentropy loss. There should be # classes floating point values per feature for y_pred and a single floating point value per feature for y_true. |
In the snippet below, there is a single floating point value per example for y_true and # classes floating pointing values per example for y_pred. The shape of y_true is [batch_size] and the shape of y_pred is [batch_size, num_classes]. |
Standalone usage: |
>>> y_true = [1, 2] |
>>> y_pred = [[0.05, 0.95, 0], [0.1, 0.8, 0.1]] |
>>> # Using 'auto'/'sum_over_batch_size' reduction type. |
>>> scce = tf.keras.losses.SparseCategoricalCrossentropy() |
>>> scce(y_true, y_pred).numpy() |
1.177 |
>>> # Calling with 'sample_weight'. |
>>> scce(y_true, y_pred, sample_weight=tf.constant([0.3, 0.7])).numpy() |
0.814 |
>>> # Using 'sum' reduction type. |
>>> scce = tf.keras.losses.SparseCategoricalCrossentropy( |
... reduction=tf.keras.losses.Reduction.SUM) |
>>> scce(y_true, y_pred).numpy() |
2.354 |
>>> # Using 'none' reduction type. |
>>> scce = tf.keras.losses.SparseCategoricalCrossentropy( |
... reduction=tf.keras.losses.Reduction.NONE) |
>>> scce(y_true, y_pred).numpy() |
array([0.0513, 2.303], dtype=float32) |
Usage with the compile() API: |
model.compile(optimizer='sgd', |
loss=tf.keras.losses.SparseCategoricalCrossentropy()) |
Poisson class |
tf.keras.losses.Poisson(reduction="auto", name="poisson") |
Computes the Poisson loss between y_true and y_pred. |
loss = y_pred - y_true * log(y_pred) |
Standalone usage: |
>>> y_true = [[0., 1.], [0., 0.]] |
>>> y_pred = [[1., 1.], [0., 0.]] |
>>> # Using 'auto'/'sum_over_batch_size' reduction type. |
>>> p = tf.keras.losses.Poisson() |
>>> p(y_true, y_pred).numpy() |
0.5 |
>>> # Calling with 'sample_weight'. |
>>> p(y_true, y_pred, sample_weight=[0.8, 0.2]).numpy() |
0.4 |
>>> # Using 'sum' reduction type. |
>>> p = tf.keras.losses.Poisson( |
... reduction=tf.keras.losses.Reduction.SUM) |
>>> p(y_true, y_pred).numpy() |
0.999 |
>>> # Using 'none' reduction type. |
>>> p = tf.keras.losses.Poisson( |
... reduction=tf.keras.losses.Reduction.NONE) |
>>> p(y_true, y_pred).numpy() |
array([0.999, 0.], dtype=float32) |
Usage with the compile() API: |
model.compile(optimizer='sgd', loss=tf.keras.losses.Poisson()) |
binary_crossentropy function |
tf.keras.losses.binary_crossentropy( |
y_true, y_pred, from_logits=False, label_smoothing=0 |
) |
Computes the binary crossentropy loss. |
Standalone usage: |
>>> y_true = [[0, 1], [0, 0]] |
>>> y_pred = [[0.6, 0.4], [0.4, 0.6]] |
>>> loss = tf.keras.losses.binary_crossentropy(y_true, y_pred) |
>>> assert loss.shape == (2,) |
>>> loss.numpy() |
array([0.916 , 0.714], dtype=float32) |
Arguments |
y_true: Ground truth values. shape = [batch_size, d0, .. dN]. |
y_pred: The predicted values. shape = [batch_size, d0, .. dN]. |
from_logits: Whether y_pred is expected to be a logits tensor. By default, we assume that y_pred encodes a probability distribution. |
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